J Anderlohr
email: jorg.anderlohr@ifp.fr

A Pires Da Cruz

R Bounaceur

F Battin Leclerc

Modeling of NO sensitization of IC engines surrogate fuels auto-ignition and combustion

Introduction

This paper presents a new chemical kinetic model developed for the simulation of auto-ignition and combustion of engine surrogate fuel mixtures sensitized by the presence of NO x . The chemical mechanism is based on the PRF auto-ignition model (n-heptane/iso-octane) of Buda et al. [START_REF] Buda | Progress toward a unified detailed kinetic model for the autoignition of alkanes from C4 to C10 between 600 and 1200[END_REF] and the NO/n-butane/n-pentane model of Glaude et al. [START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF]. The later mechanism has been taken as a reference for the reactions of NO x with larger alcanes (n-heptane, iso-octane). A coherent two components engine fuel surrogate mechanism has been generated which accounts for the influence of NO x on auto-ignition. The mechanism has been validated for temperatures between 700 K and 1100 K and pressures between 1 and 10 atm covering the temperature and pressure ranges characteristic of engine post-oxidation thermodynamic conditions. Experiments used for validation include jet stirred reactor conditions for species evolution as a function of temperature, as well as diesel HCCI engine experiments for auto-ignition delay time measurements.

During the last decades, the European Union legislation has imposed more and more stringent restrictions on vehicle exhaust emissions. For this reason, pollutant emissions control is of primary role for internal combustion engine research and development. Secondary Air Injection (SAI) might be an effective system for reducing pollutant emissions. After cold start, the SAI induces a post-oxidation of the Unburned HydroCarbons (UHC) on the exhaust line accelerating the heat-up phase of the catalytic converter and thus reducing the time for reaching its light-off temperature. A modeling of SAI in the exhaust line post-combustion is necessary to optimize the shape of exhaust manifolds in order to get an efficient pollutant after treatment system and a minimum of UHC emissions. However, the modeling of such an air injection system is difficult since conditions for an efficient post-combustion inside the exhaust line are very restrictive. A pulsed gas flow in the exhaust manifold characterized by high turbulence and strong interactions between the exhaust streams from the different engine cylinders must be described. Additional to the mixing effects between the injected air and the exhaust gas, the chemical kinetics of the pollutants reacting with the injected air must be considered. Therefore, a mathematical description of UHC post-oxidation in the exhaust line demands the coupled modeling of the fluid dynamics and the chemical kinetics.

The fluid dynamics can be computed with a 3D turbulent combustion model coupled with a convenient description of the engine post-oxidation chemistry. This paper deals with the chemical kinetics part for which a reaction mechanism has been developed for the oxidation of typical pollutants (UHC, CO, NO x ) at thermodynamic conditions characteristic for engine post-oxidation. The exhaust gas composition is complex and might contain different UHC as well as combustion products and radicals. However, in order to minimize computation CPU times, not all the species present in the exhaust gases can be considered in a chemical reaction model. Therefore, n-heptane, and iso-octane as well as NO x have been chosen as key species representing the most important molecular groups of reactants at post-oxidation conditions. Other lighter hydrocarbons like methane or ethylene as well as CO and small size radicals (OH for example) which can also be present in the exhaust gases are included in the global mechanism.

Kinetic Model

The development of the two component kinetic model of hydrocarbon oxidation in the presence of NO x is described here. The mechanism for the oxidation of PRF (Primary Reference Fuels) mixtures (n-heptane and iso-octane) has been developed by Buda et al. [START_REF] Buda | Progress toward a unified detailed kinetic model for the autoignition of alkanes from C4 to C10 between 600 and 1200[END_REF] using EXGAS [START_REF] Warth | Computer-Aided Derivation of Gas-Phase Oxidation Mechanisms: Application to the Modeling of the Oxidation of n-Butane[END_REF], an automatic mechanism generator. The computer aided generation of mechanisms, as well as the choice of the reaction types, the kinetics, and the a priori simplifications based on free radicals reactivity have been described extensively in the literature [START_REF] Warth | Computer-Aided Derivation of Gas-Phase Oxidation Mechanisms: Application to the Modeling of the Oxidation of n-Butane[END_REF].

The kinetic model for the oxidation of PRF mixtures has been coupled with a NO x sub-mechanism. This mechanism was taken from a previous modeling work on the conversion of NO to NO 2 promoted by methane, ethane, ethylene, propane, and propene [START_REF] Hori | An experimental and kinetic calculation of the promotion effect of hydrocarbons on the NO-NO2 conversion in a flow reactor[END_REF]. The kinetic model was primarily based on the GRI-MECH 3.0 [5] and the research performed by Dean and Bozzelli [START_REF] Dean | Combustion Chemistry[END_REF] and Atkinson et al. [START_REF] Atkinson | Evaluated kinetic and photochemical data for atmospheric chemistry supplement -IV -IUPAC subcommitee on gas kinetic data evaluation for atmospheric chemistry[END_REF]. Coupling reactions between species involved in the alkane oxidation model and NO x were added. These reactions were derived from a mechanism published by Glaude et al. [START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF] for the oxidation of n-butane and n-pentane in presence of nitric compounds. Figure 1 shows schematically the coupling of the PRF oxidation mechanism with NO x species. Thermochemical data was calculated using THERGAS [START_REF] Muller | Thergas -A computer-program for the evaluation of thermochemical data of molecules and free radicals in the gas phase[END_REF]. In the case of nitrogen containing compounds, the data proposed by Marinov [11] have been used. The numerical calculations were performed using the CHEMKINsoftware package [12].

Buda et al. [ 1]

Reactions coupling larger alcanes (C5, C7, C8) with + NO x presented in this paper deduced from Glaude [START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF] NOx sub -mechanism Dean [START_REF] Dean | Combustion Chemistry[END_REF] , Atkinsion [START_REF] Atkinson | Evaluated kinetic and photochemical data for atmospheric chemistry supplement -IV -IUPAC subcommitee on gas kinetic data evaluation for atmospheric chemistry[END_REF] Mechanism for the oxidation of PRF mixtures in presence of NO x

• Reaction base C0 -C2 with reactions of GRI3.0 included A (mol, cm, s, K) b (-) E (cal/mol)

Comparison between experimental and computed results

The mechanism has been tested against experimental jet stirred reactor [13] results for different pressures and temperatures. It has been validated for a temperature range from 700 K to 1100 K and pressures of 1 and 10 atm. The experimental data was obtained from Moréac [14]. The experimental setup has been described in detail in reference [13]. Figures 3a and3b compare the calculated and the experimental concentration of nheptane (Figure 3a) and CO (Figure 3b) for different initial NO concentrations. The results are presented for the stoichiometric mixtures of 1500 ppm of n-heptane with air in the presence of 0 ppm, 50 ppm and 500 ppm of NO as a function of temperature for a constant residence time of 0.2 s under atmospheric pressure.

Experiments show that above 860 K, the oxidation of nheptane is accelerated by the presence of NO, which can be observed by a reduced mole fraction of n-heptane and a simultaneous increased production of CO. As shown in Figures 3a and3b, the kinetic model predicts well the accelerating effect of NO observed experimentally.

Figures 4a and4b compare for different initial concentrations of NO the calculated and the experimental mole fractions of iso-octane and CO, respectively. The results are presented for the stoichiometric mixtures containing 1250 ppm of iso-octane with air in presence of 0 ppm and 50 ppm of NO as a function of temperature for a constant residence time of 0.2 s and 1 atm.

As in the case of n-heptane, above 880 K, the oxidation of iso-octane is accelerated by the presence of NO. As shown in Figures 4a and4b, the simulations clearly predict the catalyzing effect of NO on the oxidation of iso-octane which for increasing amounts of NO results in declined iso-octane mole fraction and simultaneous increased CO formation.

The kinetic model has also been validated against HCCI-engine experiments of Dubreuil et al. [START_REF] Dubreuil | HCCI combustion: Effect of NO in EGR[END_REF] for a fuel mixture of n-heptane (75%vol) and iso-octane (25%vol) and for an equivalence ratio of 0.3. The initial NO concentration was varied from 0 ppm up to 500 ppm. Figure 5 For small NO concentrations NO (20 ppm and 50 ppm), a decrease of the cool and main flame ignition delay can be observed. For NO concentrations from 100 ppm up to 500 ppm, only little influence of NO on the ignition delay is noticeable. Compared to experiments, the model predicts an off-set of the ignition delays of about 5 CAD ABCD. The crank angle delay between cool and main flames as well as the general trends of NOinfluence are in good agreement with the experimental data.

Conclusions and future work

The mechanism presented in this paper reproduces well the NO effect on the kinetics of n-heptane and iso-octane known from experiments performed in a Jet Stirred Reactor. The simulations performed for a HCCIengine for a mixture of n-heptane and iso-octane were also in good agreement with experimental results. Further validations on mixtures of n-heptane / iso-octane will be performed. A model extension towards ternary mixtures of n-heptane / iso-octane / toluene in presence of NO is in progress. Once the chemical reaction mechanism is validated, thermodynamic tables will be deduced and coupled to a 3D-CFD-code. The tables generated will be used as a database for a turbulent combustion model implemented in an engine CFD-code. The ensemble of generated tables and CFD-code will be used as a tool for understanding physical and chemical processes of postoxidation in IC-engines.

  21 st ICDERS -July 23-27, 2007 -Poitiers 2

Figure 2

 2 Figure2summarizes the coupling reactions with NO x species written:• The reactions of alkylperoxy ROO• and hydroperoxy-alkylperoxy HOOQOO• radicals with NO leading to NO 2 and partially oxidized products. ROO• radicals react with NO forming NO 2 and alkoxy radicals RO•. HOOQOO• radicals reacting with NO are decomposed by a global reaction to NO 2 , an hydroxyl radical OH, two formaldehyde molecules and the corresponding olefin. The rate constants chosen are identical to those proposed by Glaude for analogous reactions[START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF]. Alkoxy radicals RO• are decomposed by beta-scission with a rate constant proposed by Curran et al.[START_REF] Curran | A comprehensive modeling study of n-heptane oxidation[END_REF]. The other reactions of alkoxy radicals considered by Glaude et al.[START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF] have been neglected.• The reactions of resonance stabilized allylic radicals with NO 2 which yield NO, acrolein and an alkyl radical with the rate constant proposed by Glaude et al.[START_REF] Glaude | Kinetic Modeling of the Mutual Oxidation of NO and Larger Alkanes at Low Temperature[END_REF]. • The conversion of aklyl radicals R• with NO 2 regenerating the alkoxy radical RO•. The rate constant was taken similar to those proposed by Glarborg et al. for the reaction CH 3 +NO 2 =CH 3 O+NO [9].

Figure 1 :

 1 Figure 1: Coupling of the different reaction mechanisms

Figure 2 :

 2 Figure 2: Coupling of the different reaction mechanisms

  compares the calculated and the experimental ignition delays for the cool and main flame as a function of the initial NO concentration. The ignition delays are presented in Crank-Angle-Degrees-after-Bottom-Dead-Center (CAD ABDC).

Figure 3a :

 3a Figure 3a: Calculated (lines) and experimental (symbols) species concentration profiles of n-heptane in a jet-stirred reactor with equivalence ratio 1 at 1 atm with a residence time of 0.2 s in the presence of various amounts of NO: 0 , 50 ppm and 500 ppm. Points refer to experimental data and lines to simulated data

Figure 3b :Figure 5 :

 3b5 Figure 3b: Calculated (lines) and experimental (symbols) species concentration profiles of CO during the stoichiometric oxidation of n-heptane in a jet-stirred reactor at 1 atm with a residence time of 0.2 s in the presence of various amounts of NO: 0 ppm 50 ppm and 500 ppm. Points refer to experimental data and lines to simulated data

st ICDERS -July 23-27, 2007 -Poitiers


Natividad Planas

Diplomacy from Below or Cross-Confessional Loyalty? The "Christians of Algiers" between the Lord of Kuko and the King of Spain in the Early 1600s

Keywords:

Usually seen as actors with limited political agency, captives and slaves are, in this essay, at the core of complex diplomatic negotiations between two political authorities in a cross-confessional context. The case study presents a group of enslaved Christians in Algiers at the beginning of the seventeenth century working to restore a disrupted communication system between Spain and a rebel Muslim lord at war with the Ottomans. This lord, called Amar ben Amar bel Cadi, ruled the tiny city of Kuko and its region in the Djurdjura range (in present-day Kabylia). The goal of the Spanish military collaboration with him was to take Algiers and weaken the Ottoman Empire in North Africa. The paper argues that the captives' initiative must be understood both as diplomacy "from below" and as a cross-confessional model of loyalty. Furthermore, it compels us to rethink the agency of actors in imperial encounters and to reject the topos-often implicit in contemporary historical essays-that religious affiliation conditioned political loyalty.

Introduction

In August 1603, the "Christians of Algiers," a large group of slaves and captives in Algiers about whom the sources provide scant information, gathered ransom money to liberate and send one of their number as emissary to the king of Spain, Philip III.1 Their aim was to convince the sovereign of the world's strongest Christian empire to continue a military project against Algiers with the support of a Muslim lord, Amar ben Amar bel Cadi (called rey del Cuco by the Spaniards), a rebel leader at war with the Ottomans.2 Two months earlier the Spanish king's official envoy in charge of the negotiations with Kuko had been killed by janissaries, which had stalled the project.3

In the early modern Mediterranean, cross-confessional cooperation was not as peculiar as it may seem at first glance.4 What was more exceptional is the captives' role as self-appointed intermediaries. Surprisingly, despite the fact that the case of Spanish collaboration with the lord of Kuko has been known to historians for a while-part of the archives concerning it were published in the mid-twentieth century-this aspect seems to have gone unnoticed.5 The main reason for this neglect may lie in the fact that the case of the Christian captives-turned-diplomatic-intermediaries subverts, in several ways, commonly accepted models of captivity and political action.

The liberty of movement and action enjoyed by these captives is incompatible with contemporary Western notions of captivity based largely on the experiences of Africans in the American South. We imagine enslaved people under the arbitrary power of a master or confined to the narrow spaces of the slave quarters or North African bagnes without the opportunity to meet, make decisions, and act, even secretly.6 However, research on slavery and captivity in Islamic societies, and particularly in North Africa, suggests that while some captives certainly suffered horribly as galley rowers or otherwise, others had considerable freedom of movement and socialization,7 particularly if their masters viewed them as worthy of potentially high ransom.8

This essay will examine the role that the Christian captives and slaves of Algiers played on the imperial stage, asking whether we can consider their actions a form of diplomacy from below.9 In order to shed light on these subaltern actors' capacity to participate in the diplomatic process and address 6 The Christian captive in North Africa as powerless victim of cruel Muslim masters is a recurring topos in studies that attribute privateering, piracy and slavery only to Muslim polities in the Mediterranean. Comparisons between Christians enslaved in North Africa and African bondage in America are more frequent than comparative essays on slavery along the two shores of the Mediterranean. See for instance, Robert C. Davis, Christian Slaves, Muslim Masters: White Slavery in the Mediterranean, the Barbary Coast, and Italy, 1500-1800 (Houndmills, 2003). A critical analysis in M'Hamed Oualdi, "D'Europe et d'Orient, les approches de l'esclavage des chrétiens en terres d'Islam," Annales. Histoire, Sciences Sociales 4 (2008): 829-843. 7 See for instance Gabriel Gómez de Losada, Escuela de trabajos . . . (Madrid, 1670) questions about their initiative, the essay will analyze the historical and broader political and cultural contexts in which their actions have to be understood. I will demonstrate that their agency as well as their specific political position was not conditioned by their European background, or by their supposedly collective identity as Christians,10 but by their capacity for performing their own political culture within a specific context. Furthermore, drawing on recent studies on agency of slaves,11 the essay will approach these captives as social actors able to interact, despite their legal status, with the Muslim allies of the Spanish crown. From a global perspective, it will argue that their actions vis-à-vis Spain and Kuko have to be understood as a model of crossconfessional loyalty that transcended religious affiliation.

Historical Ties between Spain and Kuko

Officially, Spain did not maintain any diplomatic contact with Muslim countries until the end of the eighteenth century.12 Unlike the French monarchy, which had official relationships with the Ottoman Empire and established consulates in most Ottoman provinces, Spanish rulers had no appointed staff to regulate or mediate contacts with Muslim rulers. However, a multiplicity of actors conveyed commercial, strategic, and private information from the Spanish shores to North Africa and vice versa as a great number of occasions for exchange linked the two societies. Sailors, captives, merchants, and religious brokers for the release of captives were aware of the main events discussed in more frequented places in the towns (bagnes, taverns, streets, ports), and some could be temporarily charged with official missions.13 Nevertheless, at times Spain sent emissaries to discuss specific issues with Muslim rulers or secretly with political opponents.14 This was the case with Amar ben Amar bel Cadi, lord of Kuko, who was in conflict with the Ottoman authorities of Algiers around the beginning of the seventeenth century. An envoy, the Franciscan friar named Matheo de Aguirre, was sent to meet bel Cadi in September 1602 and assess the possibility of a collaboration in situ. 15 We know little about the bel Cadi dynasty, except that their principal territories were located in the mountains of Djurdjura in the interior of the Maghreb16 and that Amar ben Amar also controlled part of the coastline around the beginning of the seventeenth century (Fig. 1).17 Recent research reveals that the bel Cadis collaborated with the Barbarossa brothers in conquering the central Maghreb at the beginning of the sixteenth century.18 After Algiers became a province of the Ottoman Empire, the bel Cadis started contesting the Barbarossas' and then the Ottoman pasha's rule. At times enemies, at times allies, they fought against or alongside Ottoman rulers and continued to be powerful lords in their own region. Their contacts with the Spaniards went as far back as their conflicts with the Ottomans. When the bel Cadis were at war with the latter, they had friendly relations with the former. The very first encounter took place during the first half of the sixteenth century (1515 to 1555) when the Spanish monarchy was occupying some North African coastal cities, including Bejaïa, not far from Algiers and very close to the bel Cadi lands. The rulers of Kuko provided military support and supplies to the Spaniards, who were quite isolated from their base on the peninsula.19 Furthermore, when Emperor Charles V tried to conquer Algiers in 1541, one of Amar ben Amar's ancestors offered him his military assistance.20 After the conquest of Bejaïa by the Ottoman rulers of Algiers in 1555, contact between the Habsburgs and the bel Cadis ended for a while. A period of peace with Algiers kept Kuko away from Spain. However, when Amar ben Amar came to power around 1594, he decided to reinitiate contact. Preliminary discussions started at that time but were unsuccessful.21 Nonetheless, in 1602 Amar managed to obtain the support of Spain, the greatest enemy of the Ottomans, and declared war against the pasha of Algiers.22 At that time, Philip III intensified cross-confessional contacts with Islamic rulers, especially Persia, an Ottoman enemy, and rebel subjects of the Ottoman Empire. Were those collaborations and alliances a conscious element of a global diplomatic policy? Did the end of Philip II's reign and the signing of the peace of Vervins between France and Spain (1598) inaugurate new trends in opposing the Ottomans? Classical approaches to Mediterranean history emphasize that in the seventeenth century the Spanish rulers' commitment to the struggle against "infidels" decreased due to their more limited financial capacities and tend to consider cross-confessional diplomacy as a sign of weakness or decline in Spain's bid for Mediterranean leadership.23 However, a more careful reading of the sources invites us to reevaluate this theory and examine from a new angle the connections between this aspiring universal empire and various rebel leaders, insurgent communities, and enemies of its enemies all around the world. [START_REF] Javier | Las vecindades de las Monarquías Ibéricas[END_REF] During the last decade, the historiography of modern empires has shown that the maintenance of imperial domination was made possible by collaboration with local actors.25 Spanish power in the Mediterranean and beyond depended not only on conquests and military operations but also on a great number of alliances or friendly relationships with rulers of neighboring countries, enabling the Spanish monarchy to have an influence in territories not under its sovereignty and even those under its enemies' sovereignty. [START_REF] Javier | Introducción: las monarquías ibéricas y sus vecindades[END_REF] During the sixteenth and seventeenth centuries, local authorities of the Balkan, North African and Greek provinces of the Ottoman Empire secretly offered their loyalty to the king of Spain,27 as did the Irish Catholics28 and even the French ligueurs. [START_REF] Javier | Entre Aguirre y el gran rey. Los discursos de la elección de Felipe II al trono de Francia en 1591[END_REF] In this context of cross-confessional alliances, the Spaniards began sending munitions, arms, and money to Amar ben Amar bel Cadi. [START_REF] El Virrey | Hernando Zanoguera) al Consejo de Aragon, con una memoria de lo que embia a Berberia al Rey Cuco, con fray Mateo Aguirre[END_REF] The lord of Kuko held a fortress at an inlet called Tamagut, where Spanish emissaries would regularly land to meet with him. Troops posted there were in charge of taking visitors to the city of Kuko located in the mountains a day's march from the coast along torturously steep paths. The plan was that Amar would first fight alone against their common enemy, the pasha of Algiers, and weaken his military forces. Subsequently a Spanish fleet would be sent to North Africa to help him seize Algiers, the most powerful Muslim town in the western Mediterranean. In the end, although the Spanish crown supplied weapons to its Muslim ally on several occasions, the Spanish fleet never reached Algiers. Moreover, the official envoy Matheo de Aguirre and his men fell victim to an Ottoman ambush in Tamagut on June 13, 1603, while transporting money and military supplies to Kuko.31

The news of the massacre spread through the Mediterranean like wildfire. Enemies and rivals of the Spanish king rejoiced in the news and considered it an inevitable end to an untenable political alliance. Varying versions of the event circulated. Some claimed that the lord of Kuko had set a trap for his allies, taking advantage of their trust in order to seize the munitions and money they had brought and turn over the prisoners and spoils to the Algerian pasha.32 Although this version was false, the taking of Tamagut by Algerian janissaries was a terrible blow to Spanish-Kuko collaboration. After that, these partners could no longer communicate easily, and above all, Philip III could no longer furnish his ally with much-needed military material. The janissaries posted by the pasha at the Tamagut fortress formed a veritable military roadblock between the two allies.

The death of Aguirre had particularly negative consequences for the information system that the Franciscan had begun organizing around September 1602, at the beginning of his stay in Kuko. Aguirre had regularly been sending intelligence reports via Tamagut to the Spanish authorities. When the Ottomans occupied the inlet fortress, communication was disrupted not just between Kuko and Spain but also between Kuko and Algiers, where certain Christian captives spied for Amar ben Amar. Information from inside enemy territory was no longer available to the Spanish ruler and his Muslim allies.

It was at this time that a group of enslaved people whose identity is not clear began playing a crucial role in this cross-confessional connection. Did they act as spies or intermediaries? Although the issue has not been investigated thoroughly, it is not certain that the Spanish sovereigns maintained a permanent staff of spies in Islamic countries.33 Rather, hundreds of volunteers and self-appointed intelligence agents familiar with North Africa, such as merchants and (former) captives hoping to obtain some form of recognition or material benefits, constituted a thick network of information gathering for the Spanish crown. Through their services Spain regularly received accurate descriptions of the weakness of the enemy's military forces.34 This widely accepted custom of acting without an official mission likely informed the Christian captives' of Algiers decisions to seek direct contact with Spanish authorities after the death of the royal envoy.

The Agency of Captives

Before investigating how the enslaved Christians began restoring the connection between Spain and Kuko, let's first identify these actors. Who was hidden behind the collective identity of the "captives" or "Christians" of Algiers in October 1603? Were they all Spanish, which would explain the choice of addressing Philip III? What was their status before becoming slaves in North Africa? Did they have any prior experience in diplomatic matters?

Sources provide some of their names from the period between October 1603 and the end of 1604: Vicente Colom, probably from Mallorca; Juan Ramirez, a Sevillian stage director and the author of the report carried by the emissary; Antonio Carcassona, a Sardinian nobleman and soldier in the Spanish armies; and Salvador de la Cruz, a Portuguese friar who led a large network of people collaborating with the lord of Kuko, among others.35 However, we know very little about their involvement as agents of a secret and informal intelligence service.

Most of those we are able to identify were subjects of the king of Spain, although not all were Spanish. De la Cruz was Portuguese, and among his friends was a Genoese named Pablo, while Manuel Ricart (the emissary to Spain) was a subject of the duke of Savoy.36 However, at this time being a subject of the republic of Genoa or of the duchy of Savoy was still not so different from being a subject of the king of Spain.37 Genoa had been a traditional ally of Spain since 1528, and Charles Emmanuel of Savoy was the brother-in-law of Philip III and his ally, at least until 1610. Both the republic and the duchy were satellites of Spain.

Although the suggestion that all eight thousand slaves of Algiers38 were involved in this matter is an exaggeration, it does seem that others than just slaves played a part. Spanish documentation reveals that some Christian converts to Islam, so-called renegades,39 were involved in the Habsburg-bel Cadi collaboration. These were sometimes dissidents in a precarious position for political reasons or dissatisfied with their social advancement. The involvement of renegades in such a plot was not uncommon. Several cases have been studied by scholars, such as the Istanbul "Conspiracy of the renegades" from 1562 to 1571, organized by Juan Maria Renzo, a Genoese in the service of Spanish authorities.40 However, according to a Spanish report, the 1603-1604 plot was not exclusively an affair of captives and renegades but also involved a wide range of men in key positions and a large proportion of Algerian citizens and kuloğlus (sons of janissaries and native women).41 Before Aguirre's death in June 1603, the Algerian pasha managed to obtain some of his letters sent from Kuko to Spain. In one of them Aguirre declared that two of the three guards of the doors of the city, three of the four governors, half of the renegades, and most of the inhabitants of Algiers had declared their loyalty to him.42 Those involved in the project supported the Spanish king for political or personal reasons. Philip iii was seen by some of them as the protector of Christianity and by others, more broadly, as protector of all enemies of the Ottomans, including rebels and defectors. Political loyalty rather than any "national" or cultural identity seemed to be the common ground for those who, in one way or another, participated in this affair. Yet was the involvement within Algiers as extensive as the Spanish envoy claimed? Or did Aguirre exaggerate the extent of the support offered to the joint military action in order to convince the Spanish crown to send the fleet as soon as possible? Rather than helping us draw a specific profile of the supporters of the Spanish-Kuko connection in Algiers, Aguirre's report sheds important light on the social context, suggesting that the local tensions were political rather than religious in nature. A careful reading of this source permits us to discard simplified contrasts (e.g. Muslim masters versus Christian slaves) and gives insight into the complexities of the Algerian political and social scene. However, it does not provide specific evidence on the identity of those involved in the plot.

Even if their number and identity are unclear, we do know that some slaves and captives were involved in the military project against the Ottomans. Matheo de Aguirre had planned for them to start an uprising when Spain and Kuko attacked the town.43 However, because of the fall of Tamagut and 165 Diplomacy From Below Or Cross-confessional Loyalty Journal of early modern history 19 (2015) 153-173 Aguirre's death, the captives' role was thwarted and they needed to adapt to the situation. Now that the path from Algiers to Kuko was blocked, the captives decided to establish direct contact with Spanish authorities. They therefore subverted one of the most efficient circulation routes between the south and north shores of the Mediterranean: the ransom and release networks. They planned to raise funds and pay the ransom for one of their own, who would then be charged with entering into contact with the Spanish crown. Once liberated, he would be able to board one of the French or English merchant ships that frequented Algiers. On their way back to Europe, these ships often stopped at Mallorca, an island of the Spanish king, from which the captives' representative could easily reach the Spanish court. The elected representative of the captives was Manuel Ricart, who was from Nice and thus a subject of the duke of Savoy. According to the plan, he claimed to be French in order to negotiate his release through the mediation of the French consul.44 Since the consul had very close links to the pasha, the slaves had to be careful not to raise suspicions of their plan.

When he left Algiers, Ricart secretly transported several letters and a report, a sort of diary about events and political information concerning the Kuko-Ottoman War.45 Ricart was very well received by the viceroy of Mallorca, Fernando Zanoguera, who facilitated his travel to the court.46 The archives, however, do not reveal the outcome of this attempt to reach the king. Whether or not Ricart was able to inform Philip iii about political and strategic matters concerning Algiers remains a mystery, but his mission did restore the underground communication network between Algiers and Spain. Over the next several years, the Christian captives' self-appointed agents continued to send information to the Spanish crown via the viceroy of Mallorca.47 This intel-44 "Yo ha un año estava cautivo en Argel y el Consol de los françeses que esta alli, me ha sacado de poder de los Turcos en nombre de françés, con çien ducados que han pagado los cristianos, por dar nueva de lo que alli pasava," AGS, Estado, leg. ligence was valuable because it permitted Spain to understand the situation more precisely and envisage several attacks on Algiers, even though in the end none was undertaken.

Advising the King

The most remarkable aspect of the case is the captives' ambition to communicate directly with the Spanish king through their delegate. Was it naive for them to believe that those at the top of the social hierarchy might hear requests from below and from the edges of empire? Investigating the agency of the group of captives and slaves of Algiers raises the issue of the meaning of this action in the context of Spanish cultural politics. Would such an initiative have been acceptable to the king to whom they addressed their request? Was it imaginable for early modern European societies? Situating the case in a social and cultural framework larger than the stage of the actual crossconfessional encounter allows for a better understanding of political communication between imperial rulers and subjects acting at the empire's edges.48 It also allows us to approach the empire's borders as less exceptional than commonly conceived.

For captives to address their sovereign was not so uncommon. In September 1582, Antonio de Sosa and Juan de Bolaños, who had fled Algiers a year before, presented to Mateo Vazquez, one of the main councilors of Philip ii, an account of Algerian events from July to August 1581, written by a Genoese merchant Luis Brevez Fresco.49 At the same time, they offered to serve the king by regularly supplying North African information.50 However, there are many differences between this example and our case. First, those self-appointed spies simply offered to set up an intelligence network without advocating any specific position. Second, Bolaños and Sosa's proposal was a personal one, and we can guess that in offering the king the benefit of their experience and knowledge acquired in captivity they were looking for royal favor. Third, the Genoese merchant's report contained information that was fairly obsolete and rather useless by the time it was presented to the court by Sosa and his companion.

The initiative of October 1603, on the other hand, was a collective one. Manuel Ricart presented himself as a delegate of the collective entity, the "Christians of Algiers" or "Christian captives of Algiers." His own release had been the result of joint action. Furthermore, the purpose was not only to inform but also to advise the king. In his declaration to the viceroy of Mallorca, Ricart asserted that he was in charge of a mission to inform the Spanish king that Algiers was defenseless because all the military forces were fighting in the mountains against the lord of Kuko. This was the moment, he suggested, to dispatch a Spanish fleet to Algiers.51 A similar message was written to the Spanish court by Amar ben Amar, whose emissary managed to reach the Iberian Peninsula through Oran, a Spanish enclave in North Africa.

The lack of a Spanish official emissary able to advise the Spanish king in this crucial moment led the captives to take the decision to address him directly. Presenting themselves as a collective entity increased their chances to be heard by political authorities. Forging the idea of an enslaved community of Christians to be rescued and protected may have compelled Philip iii to uphold his moral duty as the defender of Christianity.

In its formal aspects, the initiative of the "Christian of Algiers" was in strict compliance with contemporary Western European political practices. Sending delegates to the courts was one of the political means by which early modern subjects could communicate with their ruler. In Spain, the cities of Castile used to commission deputies to the Cortes to discuss with the king (or his representatives) the level of taxes and other political matters.52 Towns frequently sent an ambassador to defend their privileges and liberties when threatened in local conflicts with royal or ecclesiastic authorities. In addressing their complaints to the king through elected delegates or deputies, they were seeking the protection of the sovereign. Once warned of the situation of which they were victims, he could give them his personal support because it was a prince's duty to protect his subjects in all cases.

Similarly, subjects' advising their king was not unusual in the Spanish context. The councils of the monarchy and the king himself received usually dozens of memoirs from private individuals advising them on all the domains of politics (financial, military, demographical, and religious). These advisers (arbitristas), as Anne Dubet, a historian of financial matters, has shown, were very familiar with the issues they tried to resolve because of their professional or personal experience.53 Thus, the captives were in a position to advise the king because they had obtained information on all the details necessary for a successful military attack. Being acquainted with some of the renegades occupying military positions facilitated their access to strategic information. Therefore we can suppose that they considered themselves competent advisers (or at least worthy of offering their counsel) to the monarch.

In any case, their spontaneous decision to alert Philip iii to the situation and the ease with which they were able to play a diplomatic role reveal that the political culture at the time was less circumscribed than is often supposed. In contrast to the idea of diplomacy as a domain of the state controlled by cultural and political elites, this case allows us to imagine it as a more open field.

Forging New Standards of Political Belonging from Below?

Analyzing the case through the perspective of political culture also raises the question of the nature of the contact between the Christian captives and the lord of Kuko. Sources show that the aim of the Christian captives was not only to restore a damaged connection in an information network but also to plead for Spanish support for Kuko. From the account of the events in Algiers, written by Juan Ramirez and brought to Spain by Ricart, it becomes clear that the captives relied on the lord of Kuko, whom they described as invincible: "Even if all the Turkish armies came to fight against Kuko, they would not manage to submit it."54

In fact, a strong link united the Muslim potentate and enslaved Christians in Algiers at the beginning of the seventeenth century. This contact was established at some point in the second half of the sixteenth century, when the bel Cadis and the captives began collaborating. The precise context in which this 53 Anne Dubet, "L'arbitrisme: un concept d'historien?," Les Cahiers du Centre de Recherches Historiques 24 (2000), http://ccrh.revues.org/2062. 54 "si en la occasion de ahora llegaran a esta tierra quarenta galeras se tomara con mucha facilidad sin perdida de veynte vidas porque la tierra la guardan viejos y mugeres porque todo el poder de Argel esta sobre el Cuco el qual sera impossible de ganar aunque venga todo el poder de Turquia . . .," Ramírez, Verdadera relacion.

occurred is unclear. It may have been during the period when Kuko was at peace with the Ottoman rulers of Algiers. Around 1560, after several decades of fighting, the bel Cadis made peace with the Algerian authorities and even established kinship ties with some of them.55 Occasions for contact with renegades and captives of Algiers were certainly numerous for the bel Cadis and their entourage at that time.

In 1594, a friar who had been enslaved in Algiers for fourteen years was the intermediary through whom Amar ben Amar addressed his first proposal of collaboration to the Habsburgs.56 From one of the bagnes of Algiers, this friar, called Pedro Cister (probably a Cistercian), wrote a letter to the viceroy of Valencia. The friar declared that he had been close to Amar ben Amar and other members of his family during his fourteen-year captivity. He also informed the Spanish court that the lord of Kuko was willing to collaborate with the king of Spain and that he offered his support for seizing the cities of Mostaganem and Bejaïa from the Ottomans. This letter reveals that, long before the Spanish sovereign sent an official envoy, the captives were at the core of a network that linked Kuko and Spain. Cister further declared that ben Amar would be a faithful ally and vouched for his loyalty. Eager to hear whether the Spanish king wanted to embark on a joint military project, ben Amar sent a weekly emissary to Cister to obtain Spanish news. However, Spain considered Mostaganem and Bejaïa insufficiently prestigious for they did not have an important role in the North African privateering that Spain was purportedly seeking to repress.

The link between Amar ben Amar and Philip iii was established less than a decade later and was formed in the same environment. The envoy Aguirre, sent to Kuko in September 1602, had been in Algiers the year before with the mission of rescuing captives.57 In that context, he came into touch with people involved with Kuko, in particular an enslaved Portuguese friar called Salvador de la Cruz who was the key person in a large network connecting Christian captives of Algiers, renegades secretly loyal to Spain, and the lord of Kuko and his subjects. Through this friar or otherwise, Aguirre arranged the journey to Spain of two of Amar ben Amar's ambassadors who were received at the Spanish court in September 1602. This visit was the beginning of the collaboration between a Muslim rebel and the world's most powerful Christian sovereign.

55 Diego de Haëdo, Topographia e historia general de Argel, repartida en cinco trabajos and Epitome de los reyes de Argel (Valladolid, 1612) fol. 74v. 56 AGS, Estado, leg. 492 (April 28, 1594). 57 Planas, "Une culture en partage," 291-292.

Planas

Matheo de Aguirre was chosen by Philip iii to organize the seizure of Algiers with the support of Amar ben Amar bel Cadi. He travelled to the Djurdjura mountain range where Kuko was located, and from there he began setting up his communication network. In this task, he benefited from the support of some of bel Cadi's advisers and was allowed to use the network of messengers and spies that they had created in the area of Algiers a long time before. The renegade Mami Espagnol, close to bel Cadi and a member of his council, paid for the operating costs of the espionage. This permitted Aguirre to keep the Spanish court informed of what was happening in Algiers and of what kind of strategic decisions were being taken by the pasha and his diwan.58

Apart from the material and economic aspects of the maintenance of espionage, the connection with Algiers was founded on the close relationships that captives had with the lord of Kuko, which engendered political as well as emotional complicity between them. This informal connection was not only older but also more powerful than the official one between Kuko and Spain. When the peace between Algiers and Kuko ended around the time that Amar ben Amar attained power, the Djurdjura Mountains became a refuge for escaped Christian captives. Amar ben Amar welcomed all those who managed to reach his lands. According to a report sent to the Spanish crown in October 1602 by Haïm Cansino from the Jewish community of Oran,59 Amar ben Amar bel Cadi was well known in North Africa as the protector of Christians and renegades at odds with the Ottomans. He allowed them to live in his lands according to their faith and protected them from harm. Cansino briefly tells the story of a fleeing renegade whom bel Cadi refused to turn over to Algiers despite large sums of money offered by Morat Raïs, the renowned head of the corsairs and the renegade's former master.60

The lord of Kuko's protection led the captives of Algiers to promote his qualities as defender of Christians and chief enemy of the Ottomans. In their accounts to Spanish authorities during 1603 and 1604, they expressed their admiration for their Muslim protector. Francisco Ribera, an enslaved friar who seems to have succeeded Salvador de la Cruz as the head of the crossconfessional network linking the captives of Algiers with Kuko, wrote about the war this lord continued to lead against the Ottomans, highlighting his military skills and his loyalty to his Spanish ally.61 Thus, the strength of the captives' bond with Amar ben Amar was such that they were willing to risk the dangers that sending a delegate to Spain entailed. They knew what would happen should the authorities of Algiers discover them; they would be executed, as were Salvador de la Cruz and other captives less than a year before. [START_REF]About Salvador de la Cruz' execution in Algiers, see Don Antonio de Carcassona avisa de cosas de Argel[END_REF] Did their loyalty and their esteem for this Muslim lord prevent them from being neutral mediators, as we usually suppose mediators to be? Given that these self-appointed intermediaries inserted subjectivity into the role they played, can we judge their initiative as a case of diplomacy from below? As already suggested, in claiming their capacity for advising the Spanish sovereign, the Christians of Algiers, whoever they were, did not improperly enter the political or diplomatic sphere. I believe the real question is whether diplomacy has ever been considered a neutral activity. Were negotiators, messengers, and delegates of the political authorities simply loyal servants impartially executing political decisions?

The Spanish monarchy seems to have expected so. In 1602, the Consejo de Estado complained that Matheo de Aguirre was too engaged in his mission. [START_REF]Deliberation of Consejo de Estado[END_REF] Promising the lord of Kuko more than the Spanish crown had authorized, he was convinced he was acting for the good of Christianity. Clearly, at the beginning of the seventeenth century, the actions of official envoys might also have been at odds with the precautions and hesitations of the Spanish government, involved in a great number of declared and undeclared conflicts around the world.

The case we have examined is perplexing, not only because of the selfmanaged diplomatic initiative by the enslaved Christians but also because these subaltern actors challenged the established models of political loyalty. Through their engagement, they upheld the notion of universal monarchy the Spanish crown still aspired to at the beginning of the seventeenth century while simultaneously manifesting their loyalty to a Muslim lord as their protector.64 This double loyalty did not fit with standards of political allegiance envisioned by Western European rulers in the early modern period, but it emanated from the capacity of actors to match their political culture to the practical situations with which they were confronted. Was this political culture more prevalent at the edges of empires than elsewhere during the early modern period? I would rather say, as others have argued recently,65 that sovereigns or the state did not have a monopolistic right in defining political and social links.

Conclusion

Diplomatic alliances and agreements depend on various actors embedded in the social sphere, even those who may be the least powerful in the social hierarchy. The combination of North African captivity and the ability to use social interactions to create connections with local opponents and external enemies of the Ottomans enabled some captives of Algiers to become genuine actors on the imperial scene from the middle of the sixteenth to the beginning of the seventeenth century. Were those captives "trans-imperial subjects," to use Natalie Rothman's insightful term, straddling linguistic, political and cultural boundaries?66 They did play an active role in creating secret networks of resistance and, furthermore, in restoring the communication between Spain and Kuko. However, sources do not establish that those who were involved with Muslim rebels of Kuko had any special linguistic or other skills that distinguished them from the mass of captives. It is possible that they did not need such skills since, as we have seen, the mountains of Kuko were not a closed world. In addition, both the entourage of the lord of Kuko and the Christian captives must have been familiar with the lingua franca, as were most of the people in North Africa.67 Nonetheless, they were able to enter into agreements not solely because of a common language but also because of a shared political culture according to which loyalty was considered as an obvious counterpart of protection.68

Figure 1

 1 Figure 1 Kuko on a map of Algiers and its hinterland, Pierre Duval (1665) (BIBLIOTHÈQUE NATIONALE DE FRANCE)

  33 Most of the literature about Habsburgs' secret services in the Ottoman Empire refers to Istanbul during the sixteenth century. See M. José Bertomeu Masià, ed., Cartas de un espía de Carlos V: la correspondencia de Jerónimo Bucchia con Antoine de Perrenot,

	Diplomacy From Below Or Cross-confessional Loyalty	163
	(Valencia, 2005); Raphaël Carrasco, "L'espionnage espagnol du Levant au XVI e siècle
	d'après la correspondance des agents espagnols à Venise," in Ambassadeurs, apprentis
	espions et maîtres comploteurs. Les systèmes de renseignement en Espagne à l'époque mod-
	erne, ed. Béatrice Pérez (Paris, 2010), 203-222; Emilio Sola and José Francisco de la Peña,
	Cervantes y la Berberia: Cervantes, mundo turco-berberisco y servicios secretos en la época
	de Felipe II (Madrid, 1996). See also Emrah Safa Gurkan, Espionage in the Sixteenth Century
	Mediterranean: Secret Diplomacy, Mediterranean Go-Betweens and the Ottoman-Habsburg
	Rivalry, (Ph.D. Diss., Georgetown, 2012).
	34 Most of this documentation remains unpublished and scattered in Spanish and Italian
	archives.

Journal of early modern history 19 (2015) 153-173

35

  Don Antonio de Carcassona avisa de cosas de Argel, AGS, Estado, leg. 192 (June 19, 1603). 36 In 1588, the duke of Savoy married Philip II's daughter, Michaela. Since 1603, three of their sons had grown up at the Spanish court. Traditionally, the Savoy got support from the Spanish Empire against France and its territorial ambitions. In exchange, the dukes allowed, for decades, Spanish armies to cross their territory to fight in the Low Countries. The configuration started changing in 1610. Pedro Marrades, El camino del Imperio: notas para el estudio de la cuestión de la Valtellina (Madrid, 1943). 37 Manuel Herrero Sánchez, "La República de Génova y la Monarquía hispánica (siglos XVI-XVII)," Hispania 65, vol. 1 (2005): 9-20. 38 João Mascarenhas, Memoravel relaçam da perda da nao conceiçam que os Turcos queymaraõ à vista da barra de Lisboa; varios sucessos das pessoas, que nella cativàraõ. E descripçaõ da Cidade de Argel, & de seu governo; & cousas muy notaveis acontecidas nestes ultimos annos de 1621 atè 1626 (Lisbon, 1627). A scientific edition of this source has been published and translated into French, João Mascarenhas, Esclave à Alger (1621-1626). Récit de captivité, ed. and trans. Paul Teyssier (Paris, 1993), 38. 39 Bartolomé et Lucille Bennassar, Les chrétiens d' Allah. L'histoire extraordinaire des rené-

gats (Paris, 1989); Mercedes García-Arenal, Conversions islamiques. Identités religieuses en Islam méditerranéen (Paris, 2001).

  192 (July 26, 1603). 45 Juan Ramírez, Verdadera relacion de todo lo que a suscedido en Argel desde el primer dia del mes de Agosto del año 1602 hasta 22 dias del mes de junio deste presente anno de 1603 (manuscript), AGS, Estado, leg. 192. 46 "Oy juebes a 26 de junio a las quatro de la tarde llego al muelle desta Ciudad de la de Argel una sagetia francesa cuyo Patron se llama Francisco Gallo franses y en su compañia truxo un cautivo Cristiano nisardo que los otros de Argel avian rescatado a respeto de imbiar con el a Vuestra Magestad la inclusa carta y de palabra hazerle relacion de las cosas que passavan entre los de Argel y el Rey Cuco," letter from Pedro Vivot, procurador real, interim viceroy of Mallorca, AGS, Estado, leg. 192 (June 26, 1603). 47 Vicente Colom, Relacion de 18 de junio asta 17 de julio 1604 años, AGS, Estado, leg. 198 (July 1604).

Journal of early modern history 19 (2015) 153-173 Planas

Rogers Brubaker and Frederick Cooper, "Beyond 'identity' ," Theory and Society 29 (2000): 1-47.

Diplomacy From Below Or Cross-confessional Loyalty Journal of early modern history 19 (2015) 153-173

Paule Wintzer, "Bougie, place forte espagnole," Bulletin de la Société de géographie d' Alger et de l' Afrique du Nord 129 (1932): 185-222. Supplying the Spaniards and even trading with them was neither unusual for Muslim communities and villages located in the hinterland of Oran or other Spanish presidios, see Beatriz Alonso Acero, Orán-Mazalquivir (1589-1639). Una sociedad española en la frontera de Berberia (Madrid,

2000), 319-414.

See for instance Subrahmanyam, "Holding the World in Balance: The Connected Histories of the Iberian Overseas Empires, 1500-1640," The American Historical Review 112 (2007):

In May 1603, the fortress was taken by the troops of Algiers. Unaware of this new situation, the Franciscan organized an expedition from Mallorca. When the Spaniards disembarked in Tamagut, they were killed by the Ottoman troops that were waiting for them. Rodríguez Joulia de Saint-Cyr, Felipe III, 51-

55. 32 This misinterpretation of facts appears in French sources, for instance in the memoires of Henry IV's minister Sully. See Maximilien Béthune (duke of Sully), Oeconomies royales, ou mémoires de Sully, in Nouvelle collection des mémoires pour servir à l'histoire de France depuis le XIII e siècle jusqu'à la fin du XVIII e , vol. II, eds. Joseph François Mihaud et Joseph François Pouloulat (Paris, 1837), 517.

Emilio Sola, Los que van y vienen. Información y fronteras en el Mediterráneo clásico del siglo XVII (Alcalá, 2005), 201-215.

Ricart's account recorded by the royal administration in Mallorca, AGS, Estado, leg. 192 (July 26, 1603).

José Ignacio Fortea Pérez, Monarquía y Cortes en la Corona de Castilla. Las ciudades ante la política fiscal de Felipe II, Cortes de Castilla y León, 1990.

Journal of early modern history 19 (2015) 153-173

In the Ottoman province of Algiers, the diwan was the council presided over by the pasha.

During the 1509-1633 period, Cansino's family held the charge of official interpreter in Oran, Jean-Frédéric Schaub, Les juifs, 65.

Relacion de avisos que da Hayen Cansino lengua, AGS, Estado, leg. 493 (October 1602).

Rodríguez Joulia de Saint-Cyr, Felipe II, 43-44 and 57-59.

Diplomacy From Below Or Cross-confessional Loyalty Journal of early modern history 19 (2015) 153-173 Despite the captives' commitment, and that of Matheo de Aguirre before them, Spain's cross-confessional project of seizing Algiers with the aid of the lord of Kuko was never realized. The Spanish crown organized two naval expeditions-the first in September 1602 and the second in August 1603but none of them reached the Algerian coast69 due to rivalries and internal conflicts among high commanding officers of the Spanish fleet, the unwillingness of some of them to conquer Algiers, and the Spanish monarchy's lack of a well-defined Mediterranean policy. Above all, the study of the collaboration between Philip iii and Amar ben Amar bel Cadi sheds light on what was going on when nothing (that is, no naval battle, no military conquest, no fact traditionally considered relevant by historians in such a context) was happening at the edges of the empires. Focusing attention on ongoing contacts rather than on the results of the military project, this case study reveals the micromechanics of the communication between European and North African actors and thus highlights the connected histories of the Spanish and Ottoman empires.