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Citric acid cycle

The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle or the TCA cycle (tricarboxylic acid cycle) —is a series of biochemical reactions to release the energy stored in nutrients through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The chemical energy released is available under the form of ATP. The Krebs cycle is used by organisms that respire (as opposed to organisms that ferment) to generate energy, either by anaerobic respiration or aerobic respiration. In addition, the cycle provides precursors of certain amino acids, as well as the reducing agent NADH, that are used in numerous other reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism. Even though it is branded as a "cycle", it is not necessary for metabolites to follow only one specific route; at least three alternative segments of the citric acid cycle have been recognized.

The name of this metabolic pathway is derived from the citric acid (a tricarboxylic acid, often called citrate, as the ionized form predominates at biological pH ) that is consumed and then regenerated by this sequence of reactions to complete the cycle. The cycle consumes acetate (in the form of acetyl-CoA) and water, reduces NAD+ to NADH, releasing carbon dioxide. The NADH generated by the citric acid cycle is fed into the oxidative phosphorylation (electron transport) pathway. The net result of these two closely linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP.

In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion. In prokaryotic cells, such as bacteria, which lack mitochondria, the citric acid cycle reaction sequence is performed in the cytosol with the proton gradient for ATP production being across the cell's surface (plasma membrane) rather than the inner membrane of the mitochondrion.

For each pyruvate molecule (from glycolysis), the overall yield of energy-containing compounds from the citric acid cycle is three NADH, one FADH2, and one GTP.

Discovery
Several of the components and reactions of the citric acid cycle were established in the 1930s by the research of Albert Szent-Györgyi, who received the Nobel Prize in Physiology or Medicine in 1937 specifically for his discoveries pertaining to fumaric acid, a component of the cycle. He made this discovery by studying pigeon breast muscle. Because this tissue maintains its oxidative capacity well after breaking down in the Latapie mincer and releasing in aqueous solutions, breast muscle of the pigeon was very well qualified for the study of oxidative reactions. The citric acid cycle itself was finally identified in 1937 by Hans Adolf Krebs and William Arthur Johnson while at the University of Sheffield, for which the former received the Nobel Prize for Physiology or Medicine in 1953, and for whom the cycle is sometimes named the "Krebs cycle".

Overview
The citric acid cycle is a metabolic pathway that connects carbohydrate, fat, and protein metabolism. The reactions of the cycle are carried out by eight enzymes that completely oxidize acetate (a two carbon molecule), in the form of acetyl-CoA, into two molecules each of carbon dioxide and water. Through catabolism of sugars, fats, and proteins, the two-carbon organic product acetyl-CoA is produced which enters the citric acid cycle. The reactions of the cycle also convert three equivalents of nicotinamide adenine dinucleotide (NAD+) into three equivalents of reduced NAD+ (NADH), one equivalent of flavin adenine dinucleotide (FAD) into one equivalent of FADH2, and one equivalent each of guanosine diphosphate (GDP) and inorganic phosphate (Pi) into one equivalent of guanosine triphosphate (GTP). The NADH and FADH2 generated by the citric acid cycle are, in turn, used by the oxidative phosphorylation pathway to generate energy-rich ATP.

One of the primary sources of acetyl-CoA is from the breakdown of sugars by glycolysis which yield pyruvate that in turn is decarboxylated by the pyruvate dehydrogenase complex generating acetyl-CoA according to the following reaction scheme:

The product of this reaction, acetyl-CoA, is the starting point for the citric acid cycle. Acetyl-CoA may also be obtained from the oxidation of fatty acids. Below is a schematic outline of the cycle:
 * The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound (oxaloacetate) to form a six-carbon compound (citrate).
 * The citrate then goes through a series of chemical transformations, losing two carboxyl groups as CO2. The carbons lost as CO2 originate from what was oxaloacetate, not directly from acetyl-CoA. The carbons donated by acetyl-CoA become part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle. Loss of the acetyl-CoA-donated carbons as CO2 requires several turns of the citric acid cycle. However, because of the role of the citric acid cycle in anabolism, they might not be lost, since many citric acid cycle intermediates are also used as precursors for the biosynthesis of other molecules.
 * Most of the electrons made available by the oxidative steps of the cycle are transferred to NAD+, forming NADH. For each acetyl group that enters the citric acid cycle, three molecules of NADH are produced. The citric acid cycle includes a series of redox reactions in mitochondria.
 * In addition, electrons from the succinate oxidation step are transferred first to the FAD cofactor of succinate dehydrogenase, reducing it to FADH2, and eventually to ubiquinone (Q) in the mitochondrial membrane, reducing it to ubiquinol (QH2) which is a substrate of the electron transfer chain at the level of Complex III.
 * For every NADH and FADH2 that are produced in the citric acid cycle, 2.5 and 1.5 ATP molecules are generated in oxidative phosphorylation, respectively.
 * At the end of each cycle, the four-carbon oxaloacetate has been regenerated, and the cycle continues.

Steps
There are ten basic steps in the citric acid cycle, as outlined below. The cycle is continuously supplied with new carbon in the form of acetyl-CoA, entering at step 0 in the table.

Two carbon atoms are oxidized to CO2, the energy from these reactions is transferred to other metabolic processes through GTP (or ATP), and as electrons in NADH and QH2. The NADH generated in the citric acid cycle may later be oxidized (donate its electrons) to drive ATP synthesis in a type of process called oxidative phosphorylation. FADH2 is covalently attached to succinate dehydrogenase, an enzyme which functions both in the citric acid cycle and the mitochondrial electron transport chain in oxidative phosphorylation. FADH2, therefore, facilitates transfer of electrons to coenzyme Q, which is the final electron acceptor of the reaction catalyzed by the succinate:ubiquinone oxidoreductase complex, also acting as an intermediate in the electron transport chain.

Mitochondria in animals, including humans, possess two succinyl-CoA synthetases: one that produces GTP from GDP, and another that produces ATP from ADP. Plants have the type that produces ATP (ADP-forming succinyl-CoA synthetase). Several of the enzymes in the cycle may be loosely associated in a multienzyme protein complex within the mitochondrial matrix.

The GTP that is formed by GDP-forming succinyl-CoA synthetase may be utilized by nucleoside-diphosphate kinase to form ATP (the catalyzed reaction is GTP + ADP → GDP + ATP).

Products
Products of the first turn of the cycle are one GTP (or ATP), three NADH, one FADH2 and two CO2.

Because two acetyl-CoA molecules are produced from each glucose molecule, two cycles are required per glucose molecule. Therefore, at the end of two cycles, the products are: two GTP, six NADH, two FADH2, and four CO2.

The above reactions are balanced if Pi represents the H2PO4− ion, ADP and GDP the ADP2− and GDP2− ions, respectively, and ATP and GTP the ATP3− and GTP3− ions, respectively.

The total number of ATP molecules obtained after complete oxidation of one glucose in glycolysis, citric acid cycle, and oxidative phosphorylation is estimated to be between 30 and 38.

Efficiency
The theoretical maximum yield of ATP through oxidation of one molecule of glucose in glycolysis, citric acid cycle, and oxidative phosphorylation is 38 (assuming 3 molar equivalents of ATP per equivalent NADH and 2 ATP per FADH2). In eukaryotes, two equivalents of NADH and two equivalents of ATP are generated in glycolysis, which takes place in the cytoplasm. If transported using the glycerol phosphate shuttle rather than the malate–aspartate shuttle, transport of two of these equivalents of NADH into the mitochondria effectively consumes two equivalents of ATP, thus reducing the net production of ATP to 36. Furthermore, inefficiencies in oxidative phosphorylation due to leakage of protons across the mitochondrial membrane and slippage of the ATP synthase/proton pump commonly reduces the ATP yield from NADH and FADH2 to less than the theoretical maximum yield. The observed yields are, therefore, closer to ~2.5 ATP per NADH and ~1.5 ATP per FADH2, further reducing the total net production of ATP to approximately 30. An assessment of the total ATP yield with newly revised proton-to-ATP ratios provides an estimate of 29.85 ATP per glucose molecule.

Variation
While the citric acid cycle is in general highly conserved, there is significant variability in the enzymes found in different taxa (note that the diagrams on this page are specific to the mammalian pathway variant).

Some differences exist between eukaryotes and prokaryotes. The conversion of D-threo-isocitrate to 2-oxoglutarate is catalyzed in eukaryotes by the NAD+-dependent EC 1.1.1.41, while prokaryotes employ the NADP+-dependent EC 1.1.1.42. Similarly, the conversion of (S)-malate to oxaloacetate is catalyzed in eukaryotes by the NAD+-dependent EC 1.1.1.37, while most prokaryotes utilize a quinone-dependent enzyme, EC 1.1.5.4.

A step with significant variability is the conversion of succinyl-CoA to succinate. Most organisms utilize EC 6.2.1.5, succinate–CoA ligase (ADP-forming) (despite its name, the enzyme operates in the pathway in the direction of ATP formation). In mammals a GTP-forming enzyme, succinate–CoA ligase (GDP-forming) (EC 6.2.1.4) also operates. The level of utilization of each isoform is tissue dependent. In some acetate-producing bacteria, such as Acetobacter aceti, an entirely different enzyme catalyzes this conversion – EC 2.8.3.18, succinyl-CoA:acetate CoA-transferase. This specialized enzyme links the TCA cycle with acetate metabolism in these organisms. Some bacteria, such as Helicobacter pylori, employ yet another enzyme for this conversion – succinyl-CoA:acetoacetate CoA-transferase (EC 2.8.3.5).

Some variability also exists at the previous step – the conversion of 2-oxoglutarate to succinyl-CoA. While most organisms utilize the ubiquitous NAD+-dependent 2-oxoglutarate dehydrogenase, some bacteria utilize a ferredoxin-dependent 2-oxoglutarate synthase (EC 1.2.7.3). Other organisms, including obligately autotrophic and methanotrophic bacteria and archaea, bypass succinyl-CoA entirely, and convert 2-oxoglutarate to succinate via succinate semialdehyde, using EC 4.1.1.71, 2-oxoglutarate decarboxylase, and EC 1.2.1.79, succinate-semialdehyde dehydrogenase.

In cancer, there are substantial metabolic derangements that occur to ensure the proliferation of tumor cells, and consequently metabolites can accumulate which serve to facilitate tumorigenesis, dubbed oncometabolites. Among the best characterized oncometabolites is 2-hydroxyglutarate which is produced through a heterozygous gain-of-function mutation (specifically a neomorphic one) in isocitrate dehydrogenase (IDH) (which under normal circumstances catalyzes the oxidation of isocitrate to oxalosuccinate, which then spontaneously decarboxylates to alpha-ketoglutarate, as discussed above; in this case an additional reduction step occurs after the formation of alpha-ketoglutarate via NADPH to yield 2-hydroxyglutarate), and hence IDH is considered an oncogene. Under physiological conditions, 2-hydroxyglutarate is a minor product of several metabolic pathways as an error but readily converted to alpha-ketoglutarate via hydroxyglutarate dehydrogenase enzymes (L2HGDH and D2HGDH) but does not have a known physiologic role in mammalian cells; of note, in cancer, 2-hydroxyglutarate is likely a terminal metabolite as isotope labelling experiments of colorectal cancer cell lines show that its conversion back to alpha-ketoglutarate is too low to measure. In cancer, 2-hydroxyglutarate serves as a competitive inhibitor for a number of enzymes that facilitate reactions via alpha-ketoglutarate in alpha-ketoglutarate-dependent dioxygenases. This mutation results in several important changes to the metabolism of the cell. For one thing, because there is an extra NADPH-catalyzed reduction, this can contribute to depletion of cellular stores of NADPH and also reduce levels of alpha-ketoglutarate available to the cell. In particular, the depletion of NADPH is problematic because NADPH is highly compartmentalized and cannot freely diffuse between the organelles in the cell. It is produced largely via the pentose phosphate pathway in the cytoplasm. The depletion of NADPH results in increased oxidative stress within the cell as it is a required cofactor in the production of GSH, and this oxidative stress can result in DNA damage. There are also changes on the genetic and epigenetic level through the function of histone lysine demethylases (KDMs) and ten-eleven translocation (TET) enzymes; ordinarily TETs hydroxylate 5-methylcytosines to prime them for demethylation. However, in the absence of alpha-ketoglutarate this cannot be done and there is hence hypermethylation of the cell's DNA, serving to promote epithelial-mesenchymal transition (EMT) and inhibit cellular differentiation. A similar phenomenon is observed for the Jumonji C family of KDMs which require a hydroxylation to perform demethylation at the epsilon-amino methyl group. Additionally, the inability of prolyl hydroxylases to catalyze reactions results in stabilization of hypoxia-inducible factor alpha, which is necessary to promote degradation of the latter (as under conditions of low oxygen there will not be adequate substrate for hydroxylation). This results in a pseudohypoxic phenotype in the cancer cell that promotes angiogenesis, metabolic reprogramming, cell growth, and migration.

Regulation
Allosteric regulation by metabolites. The regulation of the citric acid cycle is largely determined by product inhibition and substrate availability. If the cycle were permitted to run unchecked, large amounts of metabolic energy could be wasted in overproduction of reduced coenzyme such as NADH and ATP. The major eventual substrate of the cycle is ADP which gets converted to ATP. A reduced amount of ADP causes accumulation of precursor NADH which in turn can inhibit a number of enzymes. NADH, a product of all dehydrogenases in the citric acid cycle with the exception of succinate dehydrogenase, inhibits pyruvate dehydrogenase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and also citrate synthase. Acetyl-coA inhibits pyruvate dehydrogenase, while succinyl-CoA inhibits alpha-ketoglutarate dehydrogenase and citrate synthase. When tested in vitro with TCA enzymes, ATP inhibits citrate synthase and α-ketoglutarate dehydrogenase; however, ATP levels do not change more than 10% in vivo between rest and vigorous exercise. There is no known allosteric mechanism that can account for large changes in reaction rate from an allosteric effector whose concentration changes less than 10%.

Citrate is used for feedback inhibition, as it inhibits phosphofructokinase, an enzyme involved in glycolysis that catalyses formation of fructose 1,6-bisphosphate, a precursor of pyruvate. This prevents a constant high rate of flux when there is an accumulation of citrate and a decrease in substrate for the enzyme.

Regulation by calcium. Calcium is also used as a regulator in the citric acid cycle. Calcium levels in the mitochondrial matrix can reach up to the tens of micromolar levels during cellular activation. It activates pyruvate dehydrogenase phosphatase which in turn activates the pyruvate dehydrogenase complex. Calcium also activates isocitrate dehydrogenase and α-ketoglutarate dehydrogenase. This increases the reaction rate of many of the steps in the cycle, and therefore increases flux throughout the pathway.

Transcriptional regulation. There is a link between intermediates of the citric acid cycle and the regulation of hypoxia-inducible factors (HIF). HIF plays a role in the regulation of oxygen homeostasis, and is a transcription factor that targets angiogenesis, vascular remodeling, glucose utilization, iron transport and apoptosis. HIF is synthesized constitutively, and hydroxylation of at least one of two critical proline residues mediates their interaction with the von Hippel Lindau E3 ubiquitin ligase complex, which targets them for rapid degradation. This reaction is catalysed by prolyl 4-hydroxylases. Fumarate and succinate have been identified as potent inhibitors of prolyl hydroxylases, thus leading to the stabilisation of HIF.

Major metabolic pathways converging on the citric acid cycle
Several catabolic pathways converge on the citric acid cycle. Most of these reactions add intermediates to the citric acid cycle, and are therefore known as anaplerotic reactions, from the Greek meaning to "fill up". These increase the amount of acetyl CoA that the cycle is able to carry, increasing the mitochondrion's capability to carry out respiration if this is otherwise a limiting factor. Processes that remove intermediates from the cycle are termed "cataplerotic" reactions.

In this section and in the next, the citric acid cycle intermediates are indicated in italics to distinguish them from other substrates and end-products.

Pyruvate molecules produced by glycolysis are actively transported across the inner mitochondrial membrane, and into the matrix. Here they can be oxidized and combined with coenzyme A to form CO2, acetyl-CoA, and NADH, as in the normal cycle.

However, it is also possible for pyruvate to be carboxylated by pyruvate carboxylase to form oxaloacetate. This latter reaction "fills up" the amount of oxaloacetate in the citric acid cycle, and is therefore an anaplerotic reaction, increasing the cycle's capacity to metabolize acetyl-CoA when the tissue's energy needs (e.g. in muscle) are suddenly increased by activity.

In the citric acid cycle all the intermediates (e.g. citrate, iso-citrate, alpha-ketoglutarate, succinate, fumarate, malate, and oxaloacetate) are regenerated during each turn of the cycle. Adding more of any of these intermediates to the mitochondrion therefore means that that additional amount is retained within the cycle, increasing all the other intermediates as one is converted into the other. Hence the addition of any one of them to the cycle has an anaplerotic effect, and its removal has a cataplerotic effect. These anaplerotic and cataplerotic reactions will, during the course of the cycle, increase or decrease the amount of oxaloacetate available to combine with acetyl-CoA to form citric acid. This in turn increases or decreases the rate of ATP production by the mitochondrion, and thus the availability of ATP to the cell.

Acetyl-CoA, on the other hand, derived from pyruvate oxidation, or from the beta-oxidation of fatty acids, is the only fuel to enter the citric acid cycle. With each turn of the cycle one molecule of acetyl-CoA is consumed for every molecule of oxaloacetate present in the mitochondrial matrix, and is never regenerated. It is the oxidation of the acetate portion of acetyl-CoA that produces CO2 and water, with the energy thus released captured in the form of ATP. The three steps of beta-oxidation resemble the steps that occur in the production of oxaloacetate from succinate in the TCA cycle. Acyl-CoA is oxidized to trans-Enoyl-CoA while FAD is reduced to FADH2, which is similar to the oxidation of succinate to fumarate. Following, trans-enoyl-CoA is hydrated across the double bond to beta-hydroxyacyl-CoA, just like fumarate is hydrated to malate. Lastly, beta-hydroxyacyl-CoA is oxidized to beta-ketoacyl-CoA while NAD+ is reduced to NADH, which follows the same process as the oxidation of malate to oxaloacetate.

In the liver, the carboxylation of cytosolic pyruvate into intra-mitochondrial oxaloacetate is an early step in the gluconeogenic pathway which converts lactate and de-aminated alanine into glucose, under the influence of high levels of glucagon and/or epinephrine in the blood. Here the addition of oxaloacetate to the mitochondrion does not have a net anaplerotic effect, as another citric acid cycle intermediate (malate) is immediately removed from the mitochondrion to be converted into cytosolic oxaloacetate, which is ultimately converted into glucose, in a process that is almost the reverse of glycolysis.

In protein catabolism, proteins are broken down by proteases into their constituent amino acids. Their carbon skeletons (i.e. the de-aminated amino acids) may either enter the citric acid cycle as intermediates (e.g. alpha-ketoglutarate derived from glutamate or glutamine), having an anaplerotic effect on the cycle, or, in the case of leucine, isoleucine, lysine, phenylalanine, tryptophan, and tyrosine, they are converted into acetyl-CoA which can be burned to CO2 and water, or used to form ketone bodies, which too can only be burned in tissues other than the liver where they are formed, or excreted via the urine or breath. These latter amino acids are therefore termed "ketogenic" amino acids, whereas those that enter the citric acid cycle as intermediates can only be cataplerotically removed by entering the gluconeogenic pathway via malate which is transported out of the mitochondrion to be converted into cytosolic oxaloacetate and ultimately into glucose. These are the so-called "glucogenic" amino acids. De-aminated alanine, cysteine, glycine, serine, and threonine are converted to pyruvate and can consequently either enter the citric acid cycle as oxaloacetate (an anaplerotic reaction) or as acetyl-CoA to be disposed of as CO2 and water.

In fat catabolism, triglycerides are hydrolyzed to break them into fatty acids and glycerol. In the liver the glycerol can be converted into glucose via dihydroxyacetone phosphate and glyceraldehyde-3-phosphate by way of gluconeogenesis. In skeletal muscle, glycerol is used in glycolysis by converting glycerol into glycerol-3-phosphate, then into dihydroxyacetone phosphate (DHAP), then into glyceraldehyde-3-phosphate.

In many tissues, especially heart and skeletal muscle tissue, fatty acids are broken down through a process known as beta oxidation, which results in the production of mitochondrial acetyl-CoA, which can be used in the citric acid cycle. Beta oxidation of fatty acids with an odd number of methylene bridges produces propionyl-CoA, which is then converted into succinyl-CoA and fed into the citric acid cycle as an anaplerotic intermediate.

The total energy gained from the complete breakdown of one (six-carbon) molecule of glucose by glycolysis, the formation of 2 acetyl-CoA molecules, their catabolism in the citric acid cycle, and oxidative phosphorylation equals about 30 ATP molecules, in eukaryotes. The number of ATP molecules derived from the beta oxidation of a 6 carbon segment of a fatty acid chain, and the subsequent oxidation of the resulting 3 molecules of acetyl-CoA is 40.

Citric acid cycle intermediates serve as substrates for biosynthetic processes
In this subheading, as in the previous one, the TCA intermediates are identified by italics.

Several of the citric acid cycle intermediates are used for the synthesis of important compounds, which will have significant cataplerotic effects on the cycle. Acetyl-CoA cannot be transported out of the mitochondrion. To obtain cytosolic acetyl-CoA, citrate is removed from the citric acid cycle and carried across the inner mitochondrial membrane into the cytosol. There it is cleaved by ATP citrate lyase into acetyl-CoA and oxaloacetate. The oxaloacetate is returned to mitochondrion as malate (and then converted back into oxaloacetate to transfer more acetyl-CoA out of the mitochondrion). The cytosolic acetyl-CoA is used for fatty acid synthesis and the production of cholesterol. Cholesterol can, in turn, be used to synthesize the steroid hormones, bile salts, and vitamin D.

The carbon skeletons of many non-essential amino acids are made from citric acid cycle intermediates. To turn them into amino acids the alpha keto-acids formed from the citric acid cycle intermediates have to acquire their amino groups from glutamate in a transamination reaction, in which pyridoxal phosphate is a cofactor. In this reaction the glutamate is converted into alpha-ketoglutarate, which is a citric acid cycle intermediate. The intermediates that can provide the carbon skeletons for amino acid synthesis are oxaloacetate which forms aspartate and asparagine; and alpha-ketoglutarate which forms glutamine, proline, and arginine.

Of these amino acids, aspartate and glutamine are used, together with carbon and nitrogen atoms from other sources, to form the purines that are used as the bases in DNA and RNA, as well as in ATP, AMP, GTP, NAD, FAD and CoA.

The pyrimidines are partly assembled from aspartate (derived from oxaloacetate). The pyrimidines, thymine, cytosine and uracil, form the complementary bases to the purine bases in DNA and RNA, and are also components of CTP, UMP, UDP and UTP.

The majority of the carbon atoms in the porphyrins come from the citric acid cycle intermediate, succinyl-CoA. These molecules are an important component of the hemoproteins, such as hemoglobin, myoglobin and various cytochromes.

During gluconeogenesis mitochondrial oxaloacetate is reduced to malate which is then transported out of the mitochondrion, to be oxidized back to oxaloacetate in the cytosol. Cytosolic oxaloacetate is then decarboxylated to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase, which is the rate limiting step in the conversion of nearly all the gluconeogenic precursors (such as the glucogenic amino acids and lactate) into glucose by the liver and kidney.

Because the citric acid cycle is involved in both catabolic and anabolic processes, it is known as an amphibolic pathway.

Evan M.W.Duo

Glucose feeds the TCA cycle via circulating lactate
The metabolic role of lactate is well recognized as a fuel for tissues, mitochondrial cytopathies such as DPH Cytopathy, and the scientific field of oncology (tumors). In the classical Cori cycle, muscles produce lactate which is then taken up by the liver for gluconeogenesis. New studies suggest that lactate can be used as a source of carbon for the TCA cycle.

Evolution
It is believed that components of the citric acid cycle were derived from anaerobic bacteria, and that the TCA cycle itself may have evolved more than once. It may even predate biosis: the substrates appear to undergo most of the reactions spontaneously in the presence of persulfate radicals. Theoretically, several alternatives to the TCA cycle exist; however, the TCA cycle appears to be the most efficient. If several TCA alternatives had evolved independently, they all appear to have converged to the TCA cycle.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Citric acid cycle


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Talk:Citric acid cycle

Propose to revert the suggestion of CAC having possibly developed abiogenically
CAC's "central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism and may have originated abiogenically."

This language was introduced here supported by a reference to Nick Lane's "Life Ascending." While I haven't read the book, I'm skeptical it supports the claim. Eden hochbaum (talk) 19:09, 10 April 2023 (UTC)

 * removed this. Eden hochbaum (talk) 23:44, 23 April 2023 (UTC)

Figure - Overview of the citric acid cycle. The picture is not correct: coenzyme Q (electron transport chain) should be FAD. Maikel Peppelenbosch, Erasmus MC, Rotterdam 156.83.1.18 (talk) 11:26, 19 September 2023 (UTC)

 * Ubiquinone is the correct substrate of the enzyme known as succinate-coenzyme Q reductase or succinate dehydrogenase. Genome42 (talk) 23:01, 1 February 2024 (UTC)
 * The isocitrate dehydrogenase reaction is not correct. There is no free proton produced so the products should be 2-oxoglutarate + CO2 + NADH. The correct reaction has been displayed for more than half a century on the standard entries for this enzyme (see ).
 * Same for 2-oxoglutarate dehydrogenase (alpha-ketoglutarate dehydrogenase) (see ). Genome42 (talk) 23:25, 1 February 2024 (UTC)

Requested move 12 December 2023

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: not moved. (closed by non-admin page mover) — m w  (talk) (contribs) 22:07, 26 December 2023 (UTC)

Citric acid cycle → Krebs cycle – per WP:COMMONNAME

see the ngrams: https://books.google.com/ngrams/graph?content=Citric+acid+cycle%2CKrebs+cycle&year_start=1800&year_end=2019&corpus=en-2019&smoothing=3  Abo Yemen ✉  16:22, 12 December 2023 (UTC) — Relisting. Bensci54 (talk) 17:43, 19 December 2023 (UTC)
 * Oppose. If you want to use ngrams as evidence of common name use all synonyms of the article like this. By this metric, TCA cycle should be the title. By Google Scholar results TCA cycle is also the most used term, but the others are used enough that you could argue that there is no predominant common name and each are used interchangeably. ― Synpath 19:17, 13 December 2023 (UTC)
 * Comment: I advise referring to case-insensitive ngrams, for obvious reasons. The picture is dramatically different. Adumbrativus (talk) 03:53, 14 December 2023 (UTC)
 * Why is the toggle designed that it looks like it is turned on, when it is actually off. Changed my link, thanks! ― Synpath 06:34, 14 December 2023 (UTC)
 * Note: WikiProject Molecular Biology has been notified of this discussion. Bensci54 (talk) 17:43, 19 December 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
 * Oppose per case-insensitive ngrams. --Yorkporter (talk) 08:10, 20 December 2023 (UTC)

title: Talk:Citric acid cycle


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Talk:Cavalry

Eastern armies
This should be checked by someone who understands the composition of eastern armies (Persian, Indian, Chinese, etc) better than I do. — Preceding unsigned comment added by Josh Grosse (talk • contribs) 06:32, 17 October 2001 (UTC)

Explanation of change
Musketeers, pikeman etc were totally useless against properly leaded and trained cavalry, up to some 1620s, and cavalry in eastern style still was able to defeat infantry surely during napoleonic wars (i don't know any such accidents later).

Anyway, i feel that changes i did should be reworded, but i am a bit tired and i will work on it later, unless someone else will eb able to came with inflammatory sentence which would reflect difference between Western and Eastern cavalry szopen — Preceding undated comment added 14:37, 18 January 2002 (UTC)

 * They were not really useless--it's only that in a conflict between well-trained infantry and cavalry, the result entirely depended on which side broke before contact. If the infantry didn't break, the cavalry were simply repulsed and had to return in order to reform for a subsequent attack; if the infantry broke, the cavalry came in and pursued. It's that simple. Lay 18:36, 15 December 2005 (UTC)

 * Differences between Western and Eastern cavalry? "Eastern" cavalry usually had better skirmishers and skilled horsemen. Their counterpart trained more to act as closed units. But the Romans said this about their German counterparts, etc. This concerns specially Chinese AND European cavalry units in comparison to enemies from the Asian steppe! Big difference is the way lances were held. In Europe it was embedded and single handed, the rest of the world held them in the two handed Asian style to be able to parry. Wandalstouring 13:09, 1 August 2006 (UTC)

 * That sounds a bit simplistic, because Sassanids and Mamluks, despite their reliance on the bow, fought in ordered lines using a specific massed archery technique known among modern archers as "rapid shooting" or "shower shooting." Of course, they also had lighter bow-armed cavalry fighting in the more common close-range swarming method, so the picture is never a simple one. — Preceding unsigned comment added by L clausewitz (talk • contribs) 15:26, 19 October 2006 (UTC)

Dragoons vs. Mounted Infantry
My understanding was that dragoons were trained and equipped to fight as both cavalry and infantry. Mounted Infantry referred to infantry that travelled to the festivities on horseback. Edmilne 13:25, Dec 4, 2003 (UTC)

 * It is almost the same. Dragoons could fight on horseback (but were no match for real cavalry). Mounted infantry always dismounted for combat. Wandalstouring 12:59, 1 August 2006 (UTC)

 * Mounted infantry also tended to carry and use full-size infantry rifles or muskets as opposed to carbines.Intothatdarkness (talk) 13:42, 16 August 2010 (UTC)

 * My understanding was that dragoons were mounted infantry and that they were paid less than proper cavalry because of this 80.219.123.56 (talk) 20:23, 6 March 2012 (UTC)

 * Dragoons started off in the 17th century as mounted infantry. By the 19th century, they were heavy cavalry. Mounted infantry were reinvented in the second half of the 19th century. Alansplodge (talk) 17:17, 27 April 2012 (UTC)

The Stirrup
I think that there should be a comment explaining the importance of the stirrup (and saddle). It allowed the cavalry to apply the full weight of both rider and horse to the tip of his lance. Backback cavalry could only poke at the opposition for fear of unseating themselves. Edmilne 13:25, Dec 4, 2003 (UTC)

 * Some reenactment riders told me, they have no influence on thrusting with the lance. Therefore only the high saddle is important. Stirrups do have an important role for close combat with secondary weapons like swords, sabres or maces, making it possible to stand up and secure the rider while wheeling around with the horse. Note that till the Mongol invasion light cavalry in Europe and the Middle East disputed pro and contra of stirrups. Wandalstouring 12:56, 1 August 2006 (UTC)

 * Wikipedia's own article on the Lance says that "Recent evidence has suggested... that the lance charge could be (and was) effected without the benefit of stirrups." Something to consider: a hypothetical horse and rider weighing 453.59237 kilos(1000 pounds) charging at 20 miles per hour(8.9408 meters per second) have a kinetic energy of 13371.715928257 foot pounds (18129.6118092458 joules). I don't know about you but that might make my arm a little sore. Fean 06:37, 30 August 2006 (UTC)

Cavalry weakness
The reason that earlier cavalry could only attack in the flank or rear was because of the presence of disciplined, closed infantry formations like the Greek phalanx and Roman legion. No horse wil plunge itself on such a dense thicket of spears. When such formations disappeared in medieval times frontal cavalry assaults became possible. — Preceding unsigned comment added by 62.234.142.72 (talk) 10:38, 21 January 2004 (UTC)

 * Such formations did not dissapear in the Middle Ages--if they did, what will we make of the Byzantine skoutatoi formations, the Anglo-Saxon shieldwalls, and the way that the seemingly independent reinvention of pike squares in several widely separated locales hinted at the presence of a common heritage of massed spear hedge formations? Lay 18:34, 15 December 2005 (UTC)

 * Cavalry usually attacks infantry at the flanks. No need to commit suicide in their spearhedge and infantry in the MA did have spears and stood close. I started writing on cavalry tactics, firstly, before any frontal assault, firepower was used to create gaps, secondly frontal assault was rarely the favored choice by knights. Read some wiki articles. Wandalstouring 12:51, 1 August 2006 (UTC)

The idea that cavalry won't charge head on into the front of a solid line of heavy infantry is a myth, I have done a large amount of research the matter, and cavlry has charged head on into the front of solid infantry on more than one occassion and then they used infantry or lighter cavalry to follow up on their attack.

Polish Winged Hussar (talk) 16:39, 3 March 2010 (UTC) Polish Winged Hussar

Cavalry Designation
Cavalry is not a specific mode of battlefield transport, or rather a specific technology of war. Calvalry is a theory of opearation. The key component of this theory being rapid mobility. Units of the USA are not known as "Cavalry" for historical reasons, they are known as "Cavalry" becasue that is what they are. That the mobility is provided by helicopters today (and possibly tilt rotar aircraft in the future) is a minor distinction — Preceding unsigned comment added by Jeffwarnica (talk • contribs) 05:27, 9 March 2004 (UTC)

dragoons were originally mounted infantry but later on, became more of heavy cavalry. for example Napoleon's "Cuirassiers" at waterloo were dragoons. — Preceding unsigned comment added by 66.153.8.34 (talk) 18:30, 30 August 2004 (UTC)

 * I disagree - the word is specifically from cavalier, French for horseman, derived from Old Italian cavaliere, from Late Latin caballrius, from Latin caballus, horse.  Fawcett5 22:12, 8 Mar 2005 (UTC)

 * The word's origins have nothing to do with how the concept of Cavalry has evolved. I must agree that the Cavalry designations that continue today are less because of historical ties to a unit designation as Cavalry (although they are celebrated and highly treasured), and more to do with historical ties to mission and concept of employment. It was the horse's speed and mobility that gave Cavalry the advantage, just as today's "steeds" continue to do. --Born2flie 12:38, 1 August 2006 (UTC)

 * Anonymous user you have copied a statement of a military official explaining why the US calls its mobile units cavalry. We already covered this up by saying that there is modern cavalry without horses. Wandalstouring 12:43, 1 August 2006 (UTC)

 * Please don't delete my comments simply because you find it inconvenient or irrelevant to your decisions about the article. I recommend a discussion something more like, "Born2flie, we already modified the article after considering anonymous users discussion." You know, something civilized. And, I am not the anonymous user who posted the original discussion topic, and my comments, except where designated as quotes and usually with citations or reference, originate with me. Thank you. --Born2flie 22:32, 1 August 2006 (UTC)

Who deleted what? I can not remember doing anything like this on purpose. Wandalstouring 00:00, 2 August 2006 (UTC)

 * It was your first edit after I delineated between all the discussions (check the history page). I accept that it was unintentional. When my comment disappeared and you addressed the anonymous user, I took it to mean you thought I was anonymous user come back to make the case again. --Born2flie 03:26, 2 August 2006 (UTC)

Demise
Didn't the Cossacks do some important, victorious calvary operations for the Germans in WWII?-LtNOWIS 04:12, 6 Feb 2005 (UTC)

 * Yes, some did fight for Germany (often as an anti-partisan force, almost always as dragoons). Others fought with the Soviets, and occasionally cossack would fight cossack.12.150.117.30 19:17, 1 February 2006 (UTC)

Stirrups
Something needs to be said about stirrups? — Preceding unsigned comment added by 130.89.166.237 (talk) 15:00, 13 August 2005 (UTC)

 * look above, look on cavalry tactics. reading is a useful ability. Wandalstouring 00:03, 2 August 2006 (UTC)

Winged Lancers
I have removed the link to "Winged Lancers" because it seems redundant--the material is already covered in the "History" section of the "Hussar" article, which in turn already possesses a working link among the list. If anybody objects to this move then let's discuss the pros and cons here. Lay 11:39, 7 January 2006 (UTC)

 * Winged lancers were the Polish unit and they were nice enough to provide us with plenty of pictures. Currently there is rarely a cavalry picture not showing a Polish winged lancer. Wandalstouring 16:03, 3 August 2006 (UTC)

Asian Cavalry
Can somebody please help me improve this section? I know there are many cavalry forces I haven't covered, like those of the Gok Turuk, the Kushana, and the Rajputs and Marathas, but I'm hampered by a serious lack of sources down here. Lay 02:03, 13 February 2006 (UTC)

 * good job, do you have some pictures? Wandalstouring 13:48, 12 July 2006 (UTC)

I can't believe how little Turks were mentioned in this article. I mean those guys practically invented cavalry warfare! It's like not mentioning Italians in an article about Renaissance. — Preceding unsigned comment added by 88.233.98.36 (talk) 16:31, 25 September 2011 (UTC)

World War II
The last cavalry charges in modern warfare were seen in the Second World War, where Polish and Cossack cavalry regiments scored unexpected successes against German armored advances " In which battle was this? -Colin MacDonald — Preceding unsigned comment added by 203.214.121.229 (talk) 03:55, 27 May 2006 (UTC)

 * Polish cavalry scored with their sabres against tanks? Show me sources. All reports state the Polish cavalry were brave to attack, but few could report their perspective of the events afterwards. Wandalstouring 13:12, 1 August 2006 (UTC)

 * Not with their sabers. I think there have been plenty of references mentioned for the success of Polish cavalrymen in WW2, both in this article and in the more specific pages (such as the page for the Battle of Krojanty, the most classic example). Lay 13:16, 19 November 2006 (UTC)

The poles never charged tanks with their cavalry, the cavalry was used as dragoons, skirmishers, raiders and for recon as well as towing anti-tank and anti-aircraft guns, the few times the poles did charge was against german and only then when they caught them off-guard, what happened at krojanty was the poles attacked some german infantry and were attacked in turn by machine-gun bearing german APCs, the poles retreated.

Polish Winged Hussar (talk) 00:49, 6 March 2010 (UTC) Polish Winged Hussar

Infamous cavalry forces
Here is the list of infamous cavalry forces. Never mind if it stays really short.

I want to point out that we can add almost anything on horseback in the famous cavalry section. A new division could be useful like: 1. types of cavalry / 2. cavalry forces Wandalstouring 16:01, 3 August 2006 (UTC)

Expand the non-european section
I cann't imagine the most important central asia nomads cann't be placed as the center of this article.We here talk too much of european ones.--Ksyrie 07:25, 11 January 2007 (UTC)

 * Furthur more,there are no Indigenous peoples of the Americas part.--Ksyrie 07:27, 11 January 2007 (UTC)

 * Indigenous peoples of the Americas only used horses after they were introduced by the Europeans. Furthermore they did not really use them as Cavalry units as such, rather as skirmishing and raiding parties. This probably qualifies on the fringe of being Cavalry units but I wouldn't expect more than a brief mention in the article. There is also some mention of Central Asian cavalry, although I agree this should be expanded upon along with the introduction of East Asian cavalry. The article will always have a European focus however as Cavalry was undoubtedly a mainly European method of warfare. Canderra 12:29, 12 February 2007 (UTC)

 * Not really cavalry? What you've described is practically the definition of light cavalry. 62.172.108.23 (talk) 18:04, 21 January 2010 (UTC)

Overlap with Horses in warfare
There is massive overlap with Horses in warfare, formerly War Horse. I have spent too much time on it, but any brave editor who fancies a challenge.... BrainyBabe 22:34, 11 February 2007 (UTC)

 * It's true...perhaps they should just be merged? Otherwise the seperate roles of each article (whatever they may be) would have to be clearly defined. Theonlyedge 20:02, 25 April 2007 (UTC)

Past tense
Why is this article in past-tense? Mounted units do still exist. MVMosin 20:11, 17 April 2007 (UTC)

 * Good question...but the fact is; ionly a tiny fraction of essentially ceremonial/useless true military cavalry units exist today. Theonlyedge 20:00, 25 April 2007 (UTC)

Cavalry ranks?
During the late nineteenth/early twentieth century in proffessional armies, what rank did cavalry soldiers hold? I would assume they would be senior to privates, but I don't think all were officers either...does anyone know? It should be added to the history section. Theonlyedge 20:00, 25 April 2007 (UTC)

 * In the British Army, an ordinary cavalry soldier was called a Trooper. They were equal in rank and pay to an infantry private, though perhaps they had more prestige. Alansplodge (talk) 17:24, 27 April 2012 (UTC)

Text corrections
Could RiderByNight please restore the reference to the modern Australian and New Zealand Armies misplaced by his or her last edit please. Also the reference to the Canadian Governor General's Body Guard has been confused with that of the Indian 61st Cavalry. Thank you. 210.246.8.55 18:59, 26 August 2007 (UTC)

Maratha cavalry -- Saparate article needed VISHAL1976
The Marātha horseman This article may conclude with one or two extracts to give an idea of the way in which the Marātha soldiery took the field. Grant Duff describes the troopers as follows: [208] “The Marātha horsemen are commonly dressed in a pair of light breeches covering the knee, a turban which many of them fasten by passing a fold of it under the chin, a frock of quilted cotton, and a cloth round the waist, with which they generally gird on their swords in preference to securing them with their belts. The horseman is armed with a sword and shield; a proportion in each body carry matchlocks, but the great national weapon is the spear, in the use of which and the management of their horse they evince both grace and dexterity. The spearmen have generally a sword, and sometimes a shield; but the latter is unwieldy and only carried in case the spear should be broken. The trained spearmen may always be known by their riding very long, the ball of the toe touching the stirrup; some of the matchlockmen and most of the Brāhmans ride very short and ungracefully. The bridle consists of a single headstall of cotton-rope, with a small but very severe flexible bit”

12. Cavalry in the field The following account of the Marātha cavalry is given in General Hislop’s Summary of the Marātha and Pindāri Campaigns of 1817–1819:

“The Marāthas possess extraordinary skill in horsemanship, and so intimate an acquaintance with their horses, that they can make their animals do anything, even in full speed, in halting, wheeling, etc.; they likewise use the spear with remarkable dexterity, sometimes in full gallop, grasping their spears short and quickly sticking the point in the ground; still holding the handles, they turn their horse suddenly round it, thus performing on the point of a spear as on a pivot the same circle round and round again. Their horses likewise never leave the particular class or body to which they belong; so that if the rider should be knocked off, away gallops the animal after its fellows, never separating itself from the main body. Every Marātha brings his own horse and his own arms with him to the field, and possibly in the interest they possess in this private equipment we shall find their usual shyness to expose themselves or even to make a bold vigorous attack. But if armies or troops could be frightened by appearances these horses of the Marāthas would dishearten the bravest, actually darkening the plains with their numbers and clouding the horizon with [209]dust for miles and miles around. A little fighting, however, goes a great way with them, as with most others of the native powers in India.”

On this account the Marāthas were called razāh-bazān or lance-wielders. One Muhammadan historian says: “They so use the lance that no cavalry can cope with them. Some 20,000 or 30,000 lances are held up against their enemy so close together as not to leave a span between their heads. If horsemen try to ride them down the points of the spears are levelled at the assailants and they are unhorsed. While cavalry are charging them they strike their lances against each other and the noise so frightens the horses of the enemy that they turn round and bolt.”19 The battle-cries of the Marāthas were, ‘Har, Har Mahādeo,’ and ‘Gopāl, Gopāl.’20

13. Military administration An interesting description of the internal administration of the Marātha cavalry is contained in the letter on the Marāthas by Colonel Tone already quoted. But his account must refer to a period of declining efficiency and cannot represent the military system at its best:

“In the great scale of rank and eminence which is one peculiar feature of Hindu institutions the Marātha holds a very inferior situation, being just removed one degree above those castes which are considered absolutely unclean. He is happily free from the rigorous observances as regards food which fetter the actions of the higher castes. He can eat of all kinds of food with the exception of beef; can dress his meal at all times and seasons; can partake of all victuals dressed by any caste superior to his own; washing and praying are not indispensable in his order and may be practised or omitted at pleasure. The three great tribes which compose the Marātha caste are the Kunbi or farmer, the Dhangar or shepherd and the Goāla or cowherd; to this original cause may perhaps be ascribed that great simplicity of manner which distinguishes the Marātha people. Homer mentions princesses going in person to the fountain to wash their household linen. I can affirm having seen the daughters of a prince who was able to bring an army into the field much larger than the whole Greek confederacy, [210]making bread with their own hands and otherwise employed in the ordinary business of domestic housewifery. I have seen one of the most powerful chiefs of the Empire, after a day of action, assisting in kindling a fire to keep himself warm during the night, and sitting on the ground on a spread saddle-cloth dictating to his secretaries.

“The chief military force of the Marāthas consists in their cavalry, which may be divided into four distinct classes: First the Khāsi Pagah or household forces of the prince; these are always a fine well-appointed body, the horses excellent, being the property of the Sirkār, who gives a monthly allowance to each trooper of the value of about eight rupees. The second class are the cavalry furnished by the Sillādārs,21 who contract to supply a certain number of horse on specified terms, generally about Rs. 35 a month, including the trooper’s pay. The third and most numerous description are volunteers, who join the camp bringing with them their own horse and accoutrements; their pay is generally from Rs. 40 to Rs. 50 a month in proportion to the value of their horse. There is a fourth kind of native cavalry called Pindāris, who are mere marauders, serve without any pay and subsist but by plunder, a fourth part of which they give to the Sirkār; but these are so very licentious a body that they are not employed but in one or two of the Marātha services.

“The troops collected in this manner are under no discipline whatever and engage for no specific period, but quit the army whenever they please; with the exception of furnishing a picquet while in camp, they do no duty but in the day of battle.

“The Marātha cavalry is always irregularly and badly paid; the household troops scarcely ever receive money, but are furnished with a daily allowance of coarse flour and some other ingredients from the bazār which just enable them to exist. The Sillādār is very nearly as badly [211]situated. In his arrangements with the State he has allotted to him a certain proportion of jungle where he pastures his cattle; here he and his family reside, and his sole occupation when not on actual service is increasing his Pagah or troop by breeding out of his mares, of which the Marātha cavalry almost entirely consist. There are no people in the world who understand the method of rearing and multiplying the breed of cattle equal to the Marāthas. It is by no means uncommon for a Sillādār to enter a service with one mare and in a few years be able to muster a very respectable Pagah. They have many methods of rendering the animal prolific; they back their colts much earlier than we do and they are consequently more valuable as they come sooner on the effective strength.

“When called upon for actual service the Sillādār is obliged to give muster. Upon this occasion it is always necessary that the Brāhman who takes it should have a bribe; and indeed the Hāzri, as the muster is termed, is of such a nature that it could not pass by any fair or honourable means. Not only any despicable tattus are substituted in the place of horses but animals are borrowed to fill up the complement. Heel-ropes and grain-bags are produced as belonging to cattle supposed to be at grass; in short every mode is practised to impose on the Sirkār, which in turn reimburses itself by irregular and bad payments; for it is always considered if the Sillādārs receive six months’ arrears out of the year that they are exceedingly well paid. The Volunteers who join the camp are still worse situated, as they have no collective force, and money is very seldom given in a Marātha State without being extorted. In one word, the native cavalry are the worst-paid body of troops in the world. But there is another grand error in this mode of raising troops which is productive of the worst effects. Every man in a Marātha camp is totally independent; he is the proprietor of the horse he rides, which he is never inclined to risk, since without it he can get no service. This single circumstance destroys all enterprise and spirit in the soldier, whose sole business, instead of being desirous of distinguishing himself, is to keep out of the way of danger; for notwithstanding [212]every horseman on entering a service has a certain value put upon his horse, yet should he lose it even in action he never receives any compensation or at least none proportioned to his loss. If at any time a Sillādār is disgusted with the service he can go away without meeting any molestation even though in the face of an enemy. In fact the pay is in general so shamefully irregular that a man is justified in resorting to any measure, however apparently unbecoming, to attain it. It is also another very curious circumstance attending this service that many great Sillādārs have troops in the pay of two or three chiefs at the same time, who are frequently at open war with each other.

14. Sitting Dharna “To recover an arrear of pay there is but one known mode which is universally adopted in all native services, the Mughal as well as the Marātha; this is called Dharna,22 which consists in putting the debtor, be he who he will, into a state of restraint or imprisonment, until satisfaction be given or the money actually obtained. Any person in the Sirkār’s service has a right to demand his pay of the Prince or his minister, and to sit in Dharna if it be not given; nor will he meet with the least hindrance in doing so; for none would obey an order that interfered with the Dharna, as it is a common cause; nor does the soldier incur the slightest charge of mutiny for his conduct, or suffer in the smallest manner in the opinion of his Chief, so universal is the custom. The Dharna is sometimes carried to very violent lengths and may either be executed on the Prince or his minister indifferently, with the same effect; as the Chief always makes it a point of honour not to eat or drink while his Diwān is in duress; sometimes the Dharna lasts for many days, during which time the party upon whom it is exercised is not suffered to eat or drink or wash or pray, or in short is not permitted to move from the spot where he sits, which is frequently bare-headed in the sun, until the money or security be given; so general is this mode of recovery that I suppose the Marātha Chiefs may be said to be nearly one-half of their time in a state of Dharna. [213] 15. The infantry “In the various Marātha services there are very little more than a bare majority who are Marāthas by caste, and very few instances occur of their ever entering into the infantry at all. The sepoys in the pay of the different princes are recruited in Hindustān, and principally of the Rājpūt and Pūrbia caste; these are perhaps the finest race of men in the world for figure and appearance; of lofty stature, strong, graceful and athletic; of acute feelings, high military pride, quick, apprehensive, brave, prudent and economic; at the same time it must be confessed they are impatient of discipline, and naturally inclined to mutiny. They are mere soldiers of fortune and serve only for their pay. There are also a great number of Musalmāns who serve in the different Marātha armies, some of whom have very great commands.

16. Character of the Marātha armies “The Marātha cavalry at times make very long and rapid marches, in which they do not suffer themselves to be interrupted by the monsoon or any violence of weather. In very pressing exigencies it is incredible the fatigue a Marātha horseman will endure; frequently many days pass without his enjoying one regular meal, but he depends entirely for subsistence on the different corn-fields through which the army passes: a few heads of juāri, which he chafes in his hands while on horseback, will serve him for the day; his horse subsists on the same fare, and with the addition of opium, which the Marāthas frequently administer to their cattle, is enabled to perform incredible marches.”

The above analysis of the Marātha troops indicates that their real character was that of freebooting cavalry, largely of the same type as, though no doubt greatly superior in tone and discipline to the Pindāris. Like them they lived by plundering the country. “The Marāthas,” Elphinstone remarked, “are excellent foragers. Every morning at daybreak long lines of men on small horses and ponies are seen issuing from their camps in all directions, who return before night loaded with fodder for the cattle, with firewood torn down from houses, and grain dug up from the pits where it had been concealed by the villagers; while other detachments go to a distance for some days and collect proportionately [214]larger supplies of the same kind.”23 They could thus dispense with a commissariat, and being nearly all mounted were able to make extraordinarily long marches, and consequently to carry out effectively surprise attacks and when repulsed to escape injury in the retreat. Even at Pānīpat where their largest regular force took the field under Sadāsheo Rao Bhao, he had 70,000 regular and irregular cavalry and only 15,000 infantry, of whom 9000 were hired sepoys under a Muhammadan leader. The Marāthas were at their best in attacking the slow-moving and effeminate Mughal armies, while during their period of national ascendancy under the Peshwa there was no strong military power in India which could oppose their forays. When they were by the skill of their opponents at length brought to a set battle, their fighting qualities usually proved to be distinctly poor. At Pānīpat they lost the day by a sudden panic and flight after Ibrahīm Khān Gārdi had obtained for them a decided advantage; while at Argaon and Assaye their performances were contemptible. After the recovery from Pānīpat and the rise of the independent Marātha states, the assistance of European officers was invoked to discipline and train the soldiery. Link:- http://www.gutenberg.org/files/20668/20668-h/20668-h.htm

24 [215] —Preceding unsigned comment added by 121.247.252.145 (talk) 06:29, 6 December 2007 (UTC)

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Crupper
Cavalry-related additions to Crupper would be appreciated. --Una Smith (talk) 05:13, 8 September 2008 (UTC)

Argentina
Image:Granaderos-san-martin.JPG belongs somewhere here, but whether on Cavalry or Dragoon I don't know. --Una Smith (talk) 01:09, 17 October 2008 (UTC)

Roman and Greek Cavalry
I have done a large amount of research and found that the idea of roman and greek cavalry playing a minor role or being adjunct to the infantry is a myth, roman and greek cavalry were used in a decisive shock role

Polish Winged Hussar (talk) 16:44, 3 March 2010 (UTC) Polish Winged Hussar

Scope
This article does not address or connect to a discussion of the role of cavalry in the modern era, e.g., armored cavalry regiments; or current uses of cavalry or mounted forces. —Preceding unsigned comment added by 156.42.184.103 (talk) 18:22, 16 November 2010 (UTC)

 * The roles of modern armoured units are a very different concept to the horse cavalry to which this article is devoted. Any linkage is simply a historic tradition dating back to the interim period when mounted cavalry was being converted to mechanised or armoured roles and the regiments concerned wanted (not unreasonably) to preserve some aspect of their past. Wikipedia contains a significant number of easily found articles dealing with the complexities of modern armoured warfare. Adding even a summary of these to the already lengthy "Cavalry" article would probably make it impossibly long. Current uses of mounted forces (which are very restricted outside ceremonial roles) are in fact covered in the present article. 121.73.91.201 (talk) 21:37, 16 November 2010 (UTC) Buistr (talk) 18:42, 4 November 2018 (UTC)

Origins of chariots
This article does not cover that topic adequately, and whilst not the main thrust, it is worth noting this: the origins of the ahriot remain controversial. So it should present here only one view that it originatewd amongst some "indo_Iranian" Sintasha peoples. More likely the civilizations of mesopotamia, etc (Assyria, Babylonia). And this is exactly also where they later moved off the chariots and went straight to horse back. As soon as I collect sources, I will amend the origins section. Slovenski Volk (talk) 09:38, 30 December 2011 (UTC)

Indian cavalry
Incorrect link. — Preceding unsigned comment added by 20K-Man12 (talk • contribs) 01:56, 27 May 2012 (UTC)

British or American English
This article is a mish mosh of British and American English; I just counted approximately 28 armors and 22 armours for example. WP:CONSISTENCY and good writing would say one should be chosen. Is there any preference? Thanks, SchreiberBike (talk) 02:29, 14 April 2013 (UTC)

 * Difficult to apply the usual Wiki-rules in this particular instance. The subject matter of the article ranges across more than two thousand years and a great many societies. British English, American English, Indian English, Canadian English, Australian English etc are all applicable to particular sections or passages. British (or at least European/Asian) subjects are probably dominant but I don't think that the numerous US editors contributing would be happy to see their national spellings (color, armor etc) vanish from at least the paragraphs relating to North American horsemen. Better perhaps to accept that "Cavalry" is one article where multiculturalism is unavoidable - however untidy. Buistr (talk) 04:14, 14 April 2013 (UTC))

Third oldest (after infantry and chariotry)
Chariotry being older than cavalry seems an extraordinary claim to me as a layman. Can we have a source for this? There may be an issue of definitions here, because surely Eurasian nomads fought on horseback way before 2000 BC. — Preceding unsigned comment added by 78.43.93.31 (talk) 21:22, 17 April 2013 (UTC)

North and South American cavalry
I'm seeing sections dedicated entirely for Asian, Arab, Greek and numerous Eurpoean cavalry, but none from the Americas. I think that a section dedicated to American cavalry such as Native Americans (i.e. Sioux, Comance, Cheyenne, Apache), Gaucho, Llanero, Mapuche, and the cowboys/Rough Riders deserves a section. If no one objects, I'll work on it.09:51, 26 February 2015 (UTC) — Preceding unsigned comment added by Bulls123 (talk • contribs)

 * Sounds a good idea but isn't "Cavalry" too specific a subject to encompass the wide ranging topics that you propose. Essentially this article is concerned with organized and mounted military forces across the world and through the ages. As such it is already very lengthy and includes significant amounts of material on North American (Canadian and US) horse soldiers, though admittedly little as yet on their Latin American counterparts. Additional material on the notable tribal warrior/social class categories that you name would be a valuable addition to Wikipedia but might be better added to such existing articles as Apache, Rough Riders, Gauchos etc. etc. Anyway good luck with your work. Buistr (talk) 10:39, 26 February 2015 (UTC)

Equine?
Should Cavalry articles include WikiProject Equine? For example, this article? --DThomsen8 (talk) 14:41, 17 February 2016 (UTC)

 * Regretfully I don't think there would be much interest at WikiProject Equine - the people there are horse enthusiasts (and often owners) with little concern for military history. Some years ago there was friction when Milhist editors attempted to make changes to an article concerning horses in World War I - which was fiercely guarded by their WPEquine counterparts. A case of diverse cultures clashing. Buistr (talk) 22:51, 17 February 2016 (UTC)

 * Thank you for the warning and Wiki history. I added two templates to Talk:Mounted archery, and made some minor fixes to the article. We will see what happens.--DThomsen8 (talk) 01:32, 18 February 2016 (UTC)

A Commons file used on this page has been nominated for deletion
The following Wikimedia Commons file used on this page has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 15:07, 23 August 2018 (UTC)
 * Polish cavalry in Sochaczew(1939)a.jpg

Photo Size
I have added a photo of Turkish Cavalry in the aftermath of Battle of Dunplupinar, 1922, but it came out too large. If anyone can help with re-sizing of this photo (from another Wiki site) I would appreciate it. Murat (talk) 18:16, 2 January 2022 (UTC)

 * I have reduced the photo size to more closely match the surrounding text. Thanks for providing a dramatic illustration of an actual battle scene. Buistr (talk) 03:37, 3 January 2022 (UTC).

 * Thank you! Murat (talk) 23:23, 9 January 2022 (UTC)

title: Talk:Cavalry


text:
Military engineering vehicle

A military engineering vehicle is a vehicle built for construction work or for the transportation of combat engineers on the battlefield. These vehicles may be modified civilian equipment (such as the armoured bulldozers that many nations field) or purpose-built military vehicles (such as the AVRE). The first appearance of such vehicles coincided with the appearance of the first tanks, these vehicles were modified Mark V tanks for bridging and mine clearance. Modern military engineering vehicles are expected to fulfill numerous roles such as; bulldozer, crane, grader, excavator, dump truck, breaching vehicle, bridging vehicle, military ferry, amphibious crossing vehicle, and combat engineer section carrier.

World War One
A Heavy RE tank was developed shortly after World War I by Major Giffard LeQuesne Martel RE. This vehicle was a modified Mark V tank. Two support functions for these Engineer Tanks were developed: bridging and mine clearance. The bridging component involved an assault bridge, designed by Major Charles Inglis RE, called the Canal Lock Bridge, which had sufficient length to span a canal lock. Major Martel mated the bridge with the tank and used hydraulic power generated by the tank's engine to maneuver the bridge into place. For mine clearance the tanks were equipped with 2 ton rollers.

1918-1939
Between the wars various experimental bridging tanks were used to test a series of methods for bridging obstacles and developed by the Experimental Bridging Establishment (EBE). Captain SG Galpin RE conceived a prototype Light Tank Mk V to test the Scissors Assault Bridge. This concept was realised by Captain SA Stewart RE with significant input from a Mr DM Delany, a scientific civil servant in the employ of the EBE. MB Wild & Co, Birmingham, also developed a bridge that could span gaps of 26 feet using a complex system of steel wire ropes and a traveling jib, where the front section was projected and then attached to the rear section prior to launching the bridge. This system had to be abandoned due to lack of success in getting it to work, however the idea was later used successfully on the Beaver Bridge Laying Tank.

Early World War Two

Once World War Two had begun, the development of armoured vehicles for use by engineers in the field was accelerated under Delaney's direction. The EBE rapidly developed an assault bridge carried on a modified Covenanter tank capable of deploying a 24-ton tracked load capacity bridge (Class 24) that could span gaps of 30 feet. However, it did not see service in the British armed forces, and all vehicles were passed onto Allied forces such as Australia and Czechoslovakia.

A Class 30 design superseded the Class 24 with no real re-design, simply the substitution of the Covenanter tank with a suitably modified Valentine. As tanks in the war got heavier, a new bridge capable of supporting them was developed. A heavily modified Churchill used a single-piece bridge mounted on a turret-less tank and was able to lay the bridge in 90 seconds; this bridge was able to carry a 60-ton tracked or 40-ton wheeled load.

Late World War 2: Hobart's 'Funnies' and D-Day
Hobart's Funnies were a number of unusually modified tanks operated during the Second World War by the 79th Armoured Division of the British Army or by specialists from the Royal Engineers. They were designed in light of problems that more standard tanks experienced during the amphibious Dieppe Raid, so that the new models would be able to overcome the problems of the planned Invasion of Normandy. These tanks played a major part on the Commonwealth beaches during the landings. They were forerunners of the modern combat engineering vehicle and were named after their commander, Major General Percy Hobart.

Hobart's unusual, specialized tanks, nicknamed "funnies", included:
 * AVRE (Assault Vehicle Royal Engineer), used to protect engineers in an assault role, and enable combat engineering.
 * ARK (Armoured Ramp Carrier) where the tank itself was the "bridge". Multiple vehicles could be used to span gaps in both the vertical and horizontal. The tank had the turret removed and trackways fitted to the hull. Ramps were attached at each end of the trackways extending the bridging potential and allowing its use in difficult terrain. The tank would need recovery after its use was no longer required.
 * Crab: A modified Sherman tank equipped with a mine flail, a rotating cylinder of weighted chains that exploded mines in the path of the tank.
 * Armoured Bulldozer: A conventional Caterpillar D7 bulldozer fitted with armour to protect the driver and the engine. Their job was to clear the invasion beaches of obstacles and to make roads accessible by clearing rubble and filling in bomb craters. Conversions were carried out by Caterpillar importer Jack Olding & Company Ltd of Hatfield.
 * Centaur Bulldozer: A Centaur tank with the turret removed and fitted with a simple winch-operated bulldozer blade. These were produced because of a need for a well-armoured obstacle-clearing vehicle that, unlike a conventional bulldozer, would be fast enough to keep up with tank formations. They were not used on D-Day but were issued to the 79th Armoured Division in Belgium during the latter part of 1944.

In U.S. Forces, Sherman tanks were also fitted with dozer blades, and anti-mine roller devices were developed, enabling engineering operations and providing similar capabilities.

Post war
Post war, the value of the combat engineering vehicles had been proven, and armoured multi-role engineering vehicles have been added to the majority of armoured forces.

Civilian and militarized heavy equipment

Military engineering can employ a wide variety of heavy equipment in the same ways to how this equipment is used outside the military. Bulldozers, cranes, graders, excavators, dump trucks, loaders, and backhoes all see extensive use by military engineers.

Military engineers may also use civilian heavy equipment which was modified for military applications. Typically, this involves adding armour for protection from battlefield hazards such as artillery, unexploded ordnance, mines, and small arms fire. Often this protection is provided by armour plates and steel jackets. Some examples of armoured civilian heavy equipment are the IDF Caterpillar D9, American D7 TPK, Canadian D6 armoured bulldozer, cranes, graders, excavators, and M35 2-1/2 ton cargo truck.

Militarized heavy equipment may also take on the form of traditional civilian equipment designed and built to unique military specifications. These vehicles typically sacrifice some depth of capability from civilian models in order to gain greater speed and independence from prime movers. Examples of this type of vehicle include high speed backhoes such as the Australian Army's High Mobility Engineering Vehicle (HMEV) from Thales or the Canadian Army's Multi-Purpose Engineer Vehicle (MPEV) from Arva.

The main article for civilian heavy equipment is: Heavy equipment (construction)

Armoured engineering vehicle

Typically based on the platform of a main battle tank, these vehicles go by different names depending upon the country of use or manufacture. In the US the term "combat engineer vehicle (CEV)" is used, in the UK the terms "Armoured Vehicle Royal Engineers (AVRE)" or Armoured Repair and Recovery Vehicle (ARRV) are used, while in Canada and other commonwealth nations the term "armoured engineer vehicle (AEV)" is used. There is no set template for what such a vehicle will look like, yet likely features include a large dozer blade or mine ploughs, a large caliber demolition cannon, augers, winches, excavator arms and cranes or lifting booms.

These vehicles are designed to directly conduct obstacle breaching operations and to conduct other earth-moving and engineering work on the battlefield. Good examples of this type of vehicle include the UK Trojan AVRE, the Russian IMR, and the US M728 Combat Engineer Vehicle. Although the term "armoured engineer vehicle" is used specifically to describe these multi-purpose tank based engineering vehicles, that term is also used more generically in British and Commonwealth militaries to describe all heavy tank based engineering vehicles used in the support of mechanized forces. Thus, "armoured engineer vehicle" used generically would refer to AEV, AVLB, Assault Breachers, and so on.

Armoured earth mover
Lighter and less multi-functional than the CEVs or AEVs described above, these vehicles are designed to conduct earth-moving work on the battlefield and generally be anti-tank explosive proof. These vehicles have greater high speed mobility than traditional heavy equipment and are protected against the effects of blast and fragmentation. Good examples are the American M9 ACE and the UK FV180 Combat Engineer Tractor.

Breaching vehicle
These vehicles are equipped with mechanical or other means for the breaching of man made obstacles. Common types of breaching vehicles include mechanical flails, mine plough vehicles, and mine roller vehicles. In some cases, these vehicles will also mount Mine-clearing line charges. Breaching vehicles may be either converted armoured fighting vehicles or purpose built vehicles. In larger militaries, converted AFV are likely to be used as assault breachers while the breached obstacle is still covered by enemy observation and fire, and then purpose built breaching vehicles will create additional lanes for following forces.

Good examples of breaching vehicles include the US M1150 Assault Breacher Vehicle, the UK Aardvark JSFU, and the Singaporean Trailblazer.

Bridging vehicles
Several types of military bridging vehicles have been developed. An armoured vehicle-launched bridge (AVLB) is typically a modified tank hull converted to carry a bridge into battle in order to support crossing ditches, small waterways, or other gap obstacles.

Another type of bridging vehicle is the truck launched bridge. The Soviet TMM bridging truck could carry and launch a 10-meter bridge that could be daisy-chained with other TMM bridges to cross larger obstacles. More recent developments have seen the conversion of AVLB and truck launched bridge with launching systems that can be mounted on either tank or truck for bridges that are capable of supporting heavy main battle tanks.

Earlier examples of bridging vehicles include a type in which a converted tank hull is the bridge. On these vehicles, the hull deck comprises the main portion of the tread way while ramps extend from the front and rear of the vehicle to allow other vehicles to climb over the bridging vehicle and cross obstacles. An example of this type of armoured bridging vehicle was the Churchill Ark used in the Second World War.

Combat engineer section carriers
Another type of CELLs are armoured fighting vehicles which are used to transport sappers (combat engineers) and can be fitted with a bulldozer's blade and other mine-breaching devices. They are often used as APCs because of their carrying ability and heavy protection. They are usually armed with machine guns and grenade launchers and usually tracked to provide enough tractive force to push blades and rakes. Some examples are the U.S. M113 APC, IDF Puma, Nagmachon, Husky, and U.S. M1132 ESV (a Stryker variant).

Military ferries and amphibious crossing vehicles

One of the major tasks of military engineering is crossing major rivers. Several military engineering vehicles have been developed in various nations to achieve this task. One of the more common types is the amphibious ferry such as the M3 Amphibious Rig. These vehicles are self-propelled on land, they can transform into raft type ferries when in the water, and often multiple vehicles can connect to form larger rafts or floating bridges. Other types of military ferries, such as the Soviet Plavayushij Transportyor - Srednyj, are able to load while still on land and transport other vehicles cross country and over water.

In addition to amphibious crossing vehicles, military engineers may also employ several types of boats. Military assault boats are small boats propelled by oars or an outboard motor and used to ferry dismounted infantry across water.

Tank-based combat engineering vehicles
Most CEVs are armoured fighting vehicles that may be based on a tank chassis and have special attachments in order to breach obstacles. Such attachments may include dozer blades, mine rollers, cranes etc. An example of an engineering vehicle of this kind is a bridgelaying tank, which replaces the turret with a segmented hydraulic bridge. The Hobart's Funnies of the Second World War were a wide variety of armoured vehicles for combat engineering tasks. They were allocated to the initial beachhead assaults by the British and Commonwealth forces in the D-Day landings.

Churchill tank
The British Churchill tank because of its good cross-country performance and capacious interior with side hatches became the most adapted with modifications, the base unit being the AVRE carrying a large demolition gun.

M4 Sherman

 * Dozer: The bulldozer blade was a valuable battlefield tool on the WWII M4 Sherman tank. A 1943 field modification added the hydraulic dozer blade from a Caterpillar D8 to a Sherman. The later M1 dozer blade was standardized to fit any Sherman with VVSS suspension and the M1A1 would fit the wider HVSS. Some M4s made for the Engineer Corps had the blades fitted permanently and the turrets removed. In the early stages of the 1944 Battle of Normandy before the Culin Cutter, breaking through the Bocage hedgerows relied heavily on Sherman dozers.
 * M4 Doozit: Engineer Corps' Sherman dozer with demolition charge on wooden platform and T40 Whizbang rocket launcher (the Doozit did not see combat but the Whizbang did).
 * Bridgelayer: The US field-converted a few M4 in Italy with A-frame-supported bridge and heavy rear counter-weight to make the Mobile Assault Bridge. British developments for Shermans included the fascine (used by 79th Armoured Division), Crib, Twaby Ark, Octopus, Plymouth (Bailey bridge), and AVRE (SBG bridge).
 * Mine-Clearing: British conversions included the Sherman Crab. The US developed an extensive array of experimental types:
 * T15/E1/E2: Series of mine resistant Shermans based on the T14 kit. Cancelled at war's end.
 * Mine Exploder T1E1 Roller (Earthworm): Three sets of 6 discs made from armor plate.
 * Mine Exploder T1E2 Roller: Two forward units with 7 discs only. Experimental.
 * Mine Exploder T1E3/M1 Roller (Aunt Jemima): Two forward units with five 10' discs. Most widely used T1 variant, adopted as the M1. (picture)
 * Mine Exploder T1E4 Roller: 16 discs.
 * Mine Exploder T1E5 Roller: T1E3/M1 w/ smaller wheels. Experimental.
 * Mine Exploder T1E6 Roller: T1E3/M1 w/ serrated edged discs. Experimental
 * Mine Exploder T2 Flail: British Crab I mine flail.
 * Mine Exploder T3 Flail: Based on British Scorpion flail. Development stopped in 1943.
 * Mine Exploder T3E1 Flail: T3 w/ longer arms and sand filled rotor. Cancelled.
 * Mine Exploder T3E2 Flail: E1 variant, rotor replaced with steel drum of larger diameter. Development terminated at war's end.
 * Mine Exploder T4: British Crab II mine flail.
 * Mine Exploder T7: Frame with small rollers with two discs each. Abandoned.
 * Mine Exploder T8 (Johnny Walker): Steel plungers on a pivot frame designed to pound on the ground. Vehicle steering was adversely affected.
 * Mine Exploder T9: 6' Roller. Difficult to maneuver.
 * Mine Exploder T9E1: Lightened version, but proved unsatisfactory because it failed to explode all mines.
 * Mine Exploder T10: Remote control unit designed to be controlled by the following tank. Cancelled.
 * Mine Exploder T11: Six forward firing mortars to set off mines. Experimental.
 * Mine Exploder T12: 23 forward firing mortars. Apparently effective, but cancelled.
 * Mine Exploder T14: Direct modification to a Sherman tank, upgraded belly armor and reinforced tracks. Cancelled.
 * Mine Excavator T4: Plough device. Developed during 1942, but abandoned.
 * Mine Excavator T5/E1/E2: T4 variant w/ v-shaped plough. E1/E2 was a further improvement.
 * Mine Excavator T5E3: T5E1/E2 rigged to the hydraulic lift mechanism from the M1 dozer kit to control depth.
 * Mine Excavator T6: Based on the v-shape/T5, unable to control depth.
 * Mine Excavator T2/E1/E2: Based on the T4/T5's, but rigged to the hydraulic lift mechanism from the M1 dozer kit to control depth.

M60

 * M60A1 AVLB - Armored Vehicle Launched Bridge, 60 ft scissors bridge on M60A1 chassis.
 * M60 AVLM - Armored Vehicle Launched MICLIC (Mine-Clearing Line Charge), modified M60 AVLB with up to 2 MICLIC mounted over the rear of the vehicle.
 * M60 Panther - M60 modified into a remotely controlled mine clearing tank. The turret is removed with the turret ring sealed, and the front of the vehicle is fitted with mine rollers.
 * M728 CEV - M60A1-based Combat Engineer Vehicle fitted with a folding A-frame crane and winch attached to the front of the turret, and an M135 165mm demolition gun. Commonly fitted with the D7 bulldozer blade, or a mine-clearing equipment.
 * M728A1 - Upgraded version of the M728 CEV.

M1

 * M1 Grizzly Combat Mobility Vehicle (CMV) Grizzly Breacher
 * M1 Panther II Remote Controlled Mine Clearing Vehicle Panther
 * M104 Wolverine Heavy Assault Bridge Wolverine (Heavy Assault Bridge)
 * M1074 Joint Assault Bridge System
 * M1 Assault Breacher Vehicle

Leopard 1

 * Biber (Beaver) armoured vehicle-launched bridge
 * Pionierpanzer 1
 * Pionierpanzer 2 Dachs (Badger) armoured engineer vehicle

Leopard 2

 * Panzerschnellbrücke 2 (Bridge layer)
 * Pionierpanzer 3 Kodiak

T-55/54

 * T-54 Dozer - T-54 fitted with bulldozer blades for clearing soil, obstacles and snow.
 * ALT-55 - Bulldozer version of the T-55 with large flat-plate superstructure, angular concave dozer blade on front and prominent hydraulic rams for dozer blade.
 * T-55 hull fitted with an excavator body and armoured cab.
 * T-55 MARRS - Fitted with a Vickers armoured recovery vehicle kit. It has a large flat-plate turret with slightly chamfered sides, vertical rear and very chamfered front and a large A-frame crane on the front of the turret. The crane has cylindrical winch rope fed between legs of crane. A dozer blade is fitted to the hull front.
 * MT-55 or MTU-55 (Tankoviy Mostoukladchik) - Soviet designator for Czechoslovakian MT-55A bridge-layer tank with scissors bridge.
 * MTU-12 (Tankoviy Mostoukladchik) - Bridge-layer tank with 12 m single-span bridge that can carry 50 tonnes. The system entered service in 1955; today only a very small number remains in service. Combat weight: 34 tonnes.
 * MTU-20 (Ob'yekt 602) (Tankoviy Mostoukladchik) - The MTU-20 consists of a twin-treadway superstructure mounted on a modified T-54 tank chassis. Each treadway is made up of a box-type aluminum girder with a folding ramp attached to both ends to save space in the travel position. Because of that the vehicle with the bridge on board is only 11.6 m long, but the overall span length is 20 m. This is an increase of about 62% over that of the older MTU-1. The bridge is launched by the cantilever method. First the ramps are lowered and fully extended before the treadways are forward with the full load of the bridge resting on the forward support plate during launch. The span is moved out over the launching girder until the far end reaches the far bank. Next the near end is lowered onto the near bank. This method of launching gives the bridgelayer a low silhouette which makes it less vulnerable to detection and destruction.
 * MTU-20 based on the T-55 chassis.
 * BTS-1 (Bronetankoviy Tyagach Sredniy - Medium Armoured Tractor) - This is basically a turretless T-54A with a stowage basket.
 * BTS-1M - improved or remanufactured BTS-1.
 * BTS-2 (Ob'yekt 9) (Bronetankoviy Tyagach Sredniy - Medium Armoured Tractor) - BTS-1 upgraded with a hoist and a small folding crane with a capacity of 3,000 kg. It was developed on the T-54 hull in 1951; series production started in 1955. The prototype Ob.9 had a commander's cupola with DShK 1938/46 machine gun, but the production model has a square commander's hatch, opening to the right. Combat weight: 32 tons. Only a very small number remains in service.
 * BTS-3 (Bronetankoviy Tyagach Sredniy - Medium Armoured Tractor) - JVBT-55A in service with the Soviet Army.
 * BTS-4 (Bronetankoviy Tyagach Sredniy - Medium Armoured Tractor) - Similar to BTS-2 but with snorkel. In the West generally known as T-54T. There are many different models, based on the T-44, T-54, T-55 and T-62.
 * BTS-4B - Dozer blade equipped armoured recovery vehicle converted from the early -odd-shaped turret versions of the T-54.
 * BTS-4BM - Experimental version of the BTS-4B with the capacity to winch over the front of the vehicle.
 * IMR (Ob'yekt 616) (Inzhenernaya Mashina Razgrazhdeniya) - Combat engineer vehicle. It's a T-55 that had its turret replaced with a hydraulically operated 2t crane. The crane can also be fitted with a small bucket or a pair of pincer type grabs for removing trees and other obstacles. A hydraulically operated dozer blade mounts to the front of the hull; it can be used in a straight or V-configuration only. The IMR was developed in 1969 and entered service five years later.
 * SPK-12G (Samokhodniy Pod’yomniy Kran) - Heavy crane mounted on T-55 chassis. Only two were built.
 * BMR-2 (Boyevaya Mashina Razminirovaniya) - Mine clearing tank based on T-55 chassis. This vehicle has no turret but a fixed superstructure, armed with an NSVT machine gun. It is fitted with a KMT-7 mine clearing set and entered service around 1987 during the war in Afghanistan.
 * Improved version of BMR-2 that has been seen fitted with a wide variety of mine roller designs.

T-64

 * BAT-2 – Fast combat engineering vehicle with the lower hull and "small roadwheels" & suspension of the T-64. KMDB - Vehicles Based on the MT-T Prime Mover Chassis. The vehicle is powered by a V-64-4 multi-fuel diesel engine, developing 700 hp. This engine is derived from that, used on the T-72 main battle tank. The 40-ton tractor sports a very large, all axis adjustable V-shaped hydraulic dozer blade at the front, a single soil ripper spike at the rear and a 2-ton crane on the top. The crew compartment holds 8 persons (driver, commander, radio operators plus a five-man sapper squad for dismounted tasks). The highly capable BAT-2 was designed to replace the old T-54/AT-T based BAT-M, but Warsaw Pact allies received only small numbers due to its high price and the old and new vehicles served alongside each other

T-72

 * IMR-2 (Inzhenernaya Mashina Razgrashdeniya) - Combat engineering vehicle (CEV). It has a telescoping crane arm which can lift between 5 and 11 metric tons and utilizes a pincers for uprooting trees. Pivoted at the front of the vehicle is a dozer blade that can be used in a V-configuration or as a straight dozer blade. When not required it is raised clear of the ground. On the vehicle's rear, a mine-clearing system is mounted.
 * IMR-2M1 - Simplified model without the mine-clearing system. Entered service in 1987.
 * IMR-2M2 - Improved version that is better suited for operations in dangerous situations, for example in contaminated areas. It entered service in 1990 and has a modified crane arm with bucket instead off the pincers.
 * IMR-2MA - Latest version with bigger operator's cabin armed with a 12.7 mm machine gun NSV.
 * Klin-1 - Remote controlled IMR-2.
 * MTU-72 (Ob'yekt 632) (Tankovyj Mostoukladchik) - bridge layer based on T-72 chassis. The overall layout and operating method of the system are similar to those of the MTU-20 and MTU bridgelayers. The bridge, when laid, has an overall length of 20 meters. The bridge has a maximum capacity of 50,000 kg, is 3.3 meters wide, and can span a gap of 18 m. By itself, the bridge weighs 6400 kg. The time required to lay the bridge is 3 minutes, and 8 minutes for retrieval.
 * BLP 72 (Brückenlegepanzer) - The East-German army had plans to develop a new bridgelayer tank that should have been ready for series production from 1987 but after several difficulties the project was canceled.

title: Military engineering vehicle