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Area 51

Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport or Groom Lake (after the salt flat next to its airfield). Details of its operations are not made public, but the USAF says that it is an open training range, and it is commonly thought to support the development and testing of experimental aircraft and weapons systems. The USAF and CIA acquired the site in 1955, primarily for flight testing the Lockheed U-2 aircraft.

The intense secrecy surrounding the base has made it the frequent subject of conspiracy theories and a central component of unidentified flying object (UFO) folklore. It has never been declared a secret base, but all research and occurrences in Area 51 are Top Secret/Sensitive Compartmented Information (TS/SCI). The CIA publicly acknowledged the base's existence on 25 June 2013, following a Freedom of Information Act (FOIA) request filed in 2005, and declassified documents detailing its history and purpose.

Area 51 is located in the southern portion of Nevada, 83 mi north-northwest of Las Vegas. The surrounding area is a popular tourist destination, including the small town of Rachel on the "Extraterrestrial Highway".

Area 51

The original rectangular base of 6 by is now part of the so-called "Groom box", a rectangular area, measuring 23 by, of restricted airspace. The area is connected to the internal Nevada Test Site (NTS) road network, with paved roads leading south to Mercury and west to Yucca Flat. Leading northeast from the lake, the wide and well-maintained Groom Lake Road runs through a pass in the Jumbled Hills. The road formerly led to mines in the Groom basin but has been improved since their closure. Its winding course runs past a security checkpoint, but the restricted area around the base extends farther east. After leaving the restricted area, Groom Lake Road descends eastward to the floor of the Tikaboo Valley, passing the dirt-road entrances to several small ranches, before converging with State Route 375, the "Extraterrestrial Highway", south of Rachel.

Area 51 shares a border with the Yucca Flat region of the Nevada Test Site, the location of 739 of the 928 nuclear tests conducted by the United States Department of Energy at NTS. The Yucca Mountain nuclear waste repository is southwest of Groom Lake.

Groom Lake
Groom Lake is a salt flat in Nevada used for runways of the Nellis Bombing Range Test Site airport (XTA/KXTA) on the north of the Area 51 USAF military installation. The lake at 4409 ft elevation is approximately 3+3/4 mi from north to south and 3 mi from east to west at its widest point. Located within the namesake Groom Lake Valley portion of the Tonopah Basin, the lake is 25 mi south of Rachel, Nevada.

History

The origin of the name "Area 51" is unclear. It is believed to be from an Atomic Energy Commission (AEC) numbering grid, although Area 51 is not part of this system; it is adjacent to Area 15. Another explanation is that 51 was used because it was unlikely that the AEC would use the number. According to the Central Intelligence Agency (CIA), the correct names for the facility are Homey Airport (XTA/KXTA) and Groom Lake, though the name "Area 51" was used in a CIA document from the Vietnam War. The facility has also been referred to as "Dreamland" and "Paradise Ranch", among other nicknames, with the former also being the approach control call sign for the surrounding area. The USAF public relations has referred to the facility as "an operating location near Groom Dry Lake". The special use airspace around the field is referred to as Restricted Area 4808 North (R-4808N).

Lead and silver were discovered in the southern part of the Groom Range in 1864, and the English company Groome Lead Mines Limited financed the Conception Mines in the 1870s, giving the district its name (nearby mines included Maria, Willow, and White Lake). J. B. Osborne and partners acquired the controlling interest in Groom in 1876, and Osbourne's son acquired it in the 1890s. Mining continued until 1918, then resumed after World War II until the early 1950s.

The airfield on the Groom Lake site began service in 1942 as Indian Springs Air Force Auxiliary Field and consisted of two unpaved 5,000-foot (1,524 m) runways.

U-2 program

The Central Intelligence Agency (CIA) established the Groom Lake test facility in April 1955 for Project AQUATONE: the development of the Lockheed U-2 strategic reconnaissance aircraft. Project director Richard M. Bissell Jr. understood that the flight test and pilot training programs could not be conducted at Edwards Air Force Base or Lockheed's Palmdale facility, given the extreme secrecy surrounding the project. He conducted a search for a suitable testing site for the U-2 under the same extreme security as the rest of the project. He notified Lockheed, who sent an inspection team out to Groom Lake. According to Lockheed's U-2 designer Kelly Johnson: "We flew over it and within thirty seconds, you knew that was the place[...] it was right by a dry lake. Man alive, we looked at that lake, and we all looked at each other. It was another Edwards, so we wheeled around, landed on that lake, taxied up to one end of it. It was a perfect natural landing field[...] as smooth as a billiard table without anything being done to it."

The lake bed made an ideal strip for testing aircraft, and the Emigrant Valley's mountain ranges and the NTS perimeter protected the site from visitors; it was about 100 mi north of Las Vegas. The CIA asked the AEC to acquire the land, designated "Area 51" on the map, and to add it to the Nevada Test Site.

Johnson named the area "Paradise Ranch" to encourage workers to move to "the new facility in the middle of nowhere", as the CIA later described it, and the name became shortened to "the Ranch". On 4May 1955, a survey team arrived at Groom Lake and laid out a 5000 ft north–south runway on the southwest corner of the lakebed and designated a site for a base support facility. The Ranch initially consisted of little more than a few shelters, workshops, and trailer homes in which to house its small team. A little over three months later, the base consisted of a single paved runway, three hangars, a control tower, and rudimentary accommodations for test personnel. The base's few amenities included a movie theater and volleyball court. There was also a mess hall, several wells, and fuel storage tanks. CIA, Air Force, and Lockheed personnel began arriving by July 1955. The Ranch received its first U-2 delivery on 24 July 1955 from Burbank on a C-124 Globemaster II cargo plane, accompanied by Lockheed technicians on a Douglas DC-3. Regular Military Air Transport Service flights were set up between Area 51 and Lockheed's offices in Burbank, California. To preserve secrecy, personnel flew to Nevada on Monday mornings and returned to California on Friday evenings.

OXCART program

Project OXCART was established in August 1959 for "antiradar studies, aerodynamic structural tests, and engineering designs" and all later work on the Lockheed A-12. This included testing at Groom Lake, which had inadequate facilities consisting of buildings for only 150 people, a 5000 ft asphalt runway, and limited fuel, hangar, and shop space. Groom Lake had received the name "Area 51" when A-12 test facility construction began in September 1960, including a new 8500 ft runway to replace the existing runway.

Reynolds Electrical and Engineering Company (REECo) began construction of "Project 51" on 1October 1960 with double-shift construction schedules. The contractor upgraded base facilities and built a new 10000 ft runway (14/32) diagonally across the southwest corner of the lakebed. They marked an Archimedean spiral on the dry lake approximately two miles across so that an A-12 pilot approaching the end of the overrun could abort instead of plunging into the sagebrush. Area 51 pilots called it "The Hook". For crosswind landings, they marked two unpaved airstrips (runways 9/27 and 03/21) on the dry lakebed.

By August 1961, construction of the essential facilities was complete; three surplus Navy hangars were erected on the base's north side while hangar7 was new construction. The original U-2 hangars were converted to maintenance and machine shops. Facilities in the main cantonment area included workshops and buildings for storage and administration, a commissary, a control tower, a fire station, and housing. The Navy also contributed more than 130 surplus Babbitt duplex housing units for long-term occupancy facilities. Older buildings were repaired, and additional facilities were constructed as necessary. A reservoir pond surrounded by trees served as a recreational area one mile north of the base. Other recreational facilities included a gymnasium, a movie theater, and a baseball diamond. A permanent aircraft fuel tank farm was constructed by early 1962 for the special JP-7 fuel required by the A-12. Seven tanks were constructed, with a total capacity of 1,320,000 gallons.

Security was enhanced for the arrival of OXCART and the small mine was closed in the Groom basin. In January 1962, the Federal Aviation Administration (FAA) expanded the restricted airspace in the vicinity of Groom Lake, and the lakebed became the center of a 600-square mile addition to restricted area R-4808N. The CIA facility received eight USAF F-101 Voodoos for training, two T-33 Shooting Star trainers for proficiency flying, a C-130 Hercules for cargo transport, a U-3A for administrative purposes, a helicopter for search and rescue, and a Cessna 180 for liaison use, and Lockheed provided an F-104 Starfighter for use as a chase plane.

The first A-12 test aircraft was covertly trucked from Burbank on 26 February 1962 and arrived at Groom Lake on 28 February. It made its first flight 26 April 1962 when the base had over 1,000 personnel. The closed airspace above Groom Lake was within the Nellis Air Force Range airspace, and pilots saw the A-12 20 to 30 times. Groom was also the site of the first Lockheed D-21 drone test flight on 22 December 1964. By the end of 1963, nine A-12s were at Area 51, assigned to the CIA-operated "1129th Special Activities Squadron".

D-21 Tagboard

Following the loss of Gary Powers' U-2 over the Soviet Union, there were several discussions about using the A-12 OXCART as an unpiloted drone aircraft. Although Kelly Johnson had come to support the idea of drone reconnaissance, he opposed the development of an A-12 drone, contending that the aircraft was too large and complex for such a conversion. However, the Air Force agreed to fund the study of a high-speed, high-altitude drone aircraft in October 1962. The Air Force interest seems to have moved the CIA to take action, the project designated "Q-12". By October 1963, the drone's design had been finalized. At the same time, the Q-12 underwent a name change. To separate it from the other A-12-based projects, it was renamed the "D-21". (The "12" was reversed to "21"). "Tagboard" was the project's code name.

The first D-21 was completed in the spring of 1964 by Lockheed. After four more months of checkouts and static tests, the aircraft was shipped to Groom Lake and reassembled. It was to be carried by a two-seat derivative of the A-12, designated the "M-21". When the D-21/M-21 reached the launch point, the first step would be to blow off the D-21's inlet and exhaust covers. With the D-21/M-21 at the correct speed and altitude, the LCO would start the ramjet and the other systems of the D-21. "With the D-21's systems activated and running, and the launch aircraft at the correct point, the M-21 would begin a slight pushover, the LCO would push a final button, and the D-21 would come off the pylon".

Difficulties were addressed throughout 1964 and 1965 at Groom Lake with various technical issues. Captive flights showed unforeseen aerodynamic difficulties. By late January 1966, more than a year after the first captive flight, everything seemed ready. The first D-21 launch was made on 5March 1966 with a successful flight, with the D-21 flying 120 miles with limited fuel. A second D-21 flight was successful in April 1966 with the drone flying 1,200 miles, reaching Mach 3.3 and 90,000 feet. An accident on 30 July 1966 with a fully fueled D-21, on a planned checkout flight, suffered from an unstart of the drone after its separation, causing it to collide with the M-21 launch aircraft. The two crewmen ejected and landed in the ocean 150 miles offshore. One crew member was picked up by a helicopter, but the other, having survived the aircraft breakup and ejection, drowned when sea water entered his pressure suit. Kelly Johnson personally cancelled the entire program, having had serious doubts about its feasibility from the start. A number of D-21s had already been produced, and rather than scrapping the whole effort, Johnson again proposed to the Air Force that they be launched from a B-52H bomber.

By late summer of 1967, the modification work to both the D-21 (now designated D-21B) and the B-52Hs was complete. The test program could now resume. The test missions were flown out of Groom Lake, with the actual launches over the Pacific. The first D-21B to be flown was Article 501, the prototype. The first attempt was made on 28 September 1967 and ended in complete failure. As the B-52 was flying toward the launch point, the D-21B fell off the pylon. The B-52H gave a sharp lurch as the drone fell free. The booster fired and was "quite a sight from the ground". The failure was traced to a stripped nut on the forward right attachment point on the pylon. Several more tests were made, none of which met with success. However, the fact is that the resumptions of D-21 tests took place against a changing reconnaissance background. The A-12 had finally been allowed to deploy, and the SR-71 was soon to replace it. At the same time, new developments in reconnaissance satellite technology were nearing operation. Up to this point, the limited number of satellites available restricted coverage to the Soviet Union. A new generation of reconnaissance satellites could soon cover targets anywhere in the world. The satellites' resolution would be comparable to that of aircraft but without the slightest political risk. Time was running out for the Tagboard.

Several more test flights, including two over China, were made from Beale AFB, California, in 1969 and 1970, to varying degrees of success. On 15 July 1971, Kelly Johnson received a wire canceling the D-21B program. The remaining drones were transferred by a C-5A and placed in dead storage. The tooling used to build the D-21Bs was ordered destroyed. Like the A-12 Oxcart, the D-21B Tagboard drones remained a Black airplane, even in retirement. Their existence was not suspected until August 1976, when the first group was placed in storage at the Davis-Monthan AFB Military Storage and Disposition Center. A second group arrived in 1977. They were labeled "GTD-21Bs" (GT stood for ground training).

Davis-Monthan is an open base, with public tours of the storage area at the time, so the odd-looking drones were soon spotted and photos began appearing in magazines. Speculation about the D-21Bs circulated within aviation circles for years, and it was not until 1982 that details of the Tagboard program were released. However, it was not until 1993 that the B-52/D-21B program was made public. That same year, the surviving D-21Bs were released to museums.

Foreign technology evaluation
During the Cold War, one of the missions carried out by the United States was the test and evaluation of captured Soviet fighter aircraft. Beginning in the late 1960s, and for several decades, Area 51 played host to an assortment of Soviet-built aircraft.

Munir Redfa's defection with a Mikoyan-Gurevich MiG-21 from Iraq for Israel's Mossad in Operation Diamond led to the HAVE DOUGHNUT, HAVE DRILL and HAVE FERRY programs. The first MiGs flown in the United States were used to evaluate the aircraft in performance, technical, and operational capabilities, pitting the types against U.S. fighters.

This was not a new mission, as testing of foreign technology by the USAF began during World War II. After the war, testing of acquired foreign technology was performed by the Air Technical Intelligence Center (ATIC, which became very influential during the Korean War), under the direct command of the Air Materiel Control Department. In 1961, ATIC became the Foreign Technology Division (FTD) and was reassigned to Air Force Systems Command. ATIC personnel were sent anywhere where foreign aircraft could be found.

The focus of Air Force Systems Command limited the use of the fighter as a tool with which to train the front line tactical fighter pilots. Air Force Systems Command recruited its pilots from the Air Force Flight Test Center at Edwards Air Force Base, California, who were usually graduates from various test pilot schools. Tactical Air Command selected its pilots primarily from the ranks of the Weapons School graduates.

In August 1966, Iraqi Air Force fighter pilot Captain Munir Redfa defected, flying his MiG-21 to Israel after being ordered to attack Iraqi Kurd villages with napalm. His aircraft was transferred to Groom Lake in late 1967 for study. Israel loaned the MiG-21 to the US Air Force from January 1968 to April 1968. In 1968, the US Air Force and Navy jointly formed a project known as HAVE DOUGHNUT in which Air Force Systems Command, Tactical Air Command, and the U.S. Navy's Air Test and Evaluation Squadron Four (VX-4) flew this acquired Soviet made aircraft in simulated air combat training. As U.S. possession of the Soviet MiG-21 was, itself, secret, it was tested at Groom Lake. A joint Air Force-Navy team was assembled for a series of dogfight tests.

Comparisons between the F-4 and the MiG-21 indicated that, on the surface, they were evenly matched. The HAVE DOUGHNUT tests showed the skill of the man in the cockpit was what made the difference. When the Navy or Air Force pilots flew the MiG-21, the results were a draw; the F-4 would win some fights, the MiG-21 would win others. There were no clear advantages. The problem was not with the planes, but with the pilots flying them. The pilots would not fly either plane to its limits. One of the Navy pilots was Marland W. "Doc" Townsend, then commander of VF-121, the F-4 training squadron at NAS Miramar. He was an engineer and a Korean War veteran and had flown almost every navy aircraft. When he flew against the MiG-21, he would outmaneuver it every time. The Air Force pilots would not go vertical in the MiG-21. The HAVE DOUGHNUT project officer was Tom Cassidy, a pilot with VX-4, the Navy's Air Development Squadron at Point Mugu. He had been watching as Townsend "waxed" the Air Force MiG-21 pilots. Cassidy climbed into the MiG-21 and went up against Townsend's F-4. This time the result was far different. Cassidy was willing to fight in the vertical, flying the plane to the point where it was buffeting, just above the stall. Cassidy was able to get on the F-4's tail. After the flight, they realized the MiG-21 turned better than the F-4 at lower speeds. The key was for the F-4 to keep its speed up. An F-4 had defeated the MiG-21; the weakness of the Soviet plane had been found. Further test flights confirmed what was learned. It was also clear that the MiG-21 was a formidable enemy. United States pilots would have to fly much better than they had been to beat it. This would require a special school to teach advanced air combat techniques.

On 12 August 1968, two Syrian air force lieutenants, Walid Adham and Radfan Rifai, took off in a pair of MiG-17Fs on a training mission. They lost their way and, believing they were over Lebanon, landed at the Betzet Landing Field in northern Israel. (One version has it that they were led astray by an Arabic-speaking Israeli). Prior to the end of 1968 these MiG-17s were transferred from Israeli stocks and added to the Area 51 test fleet. The aircraft were given USAF designations and fake serial numbers so that they could be identified in DOD standard flight logs. As in the earlier program, a small group of Air Force and Navy pilots conducted mock dogfights with the MiG-17s. Selected instructors from the Navy's Top Gun school at NAS Miramar, California, were chosen to fly against the MiGs for familiarization purposes. Very soon, the MiG-17's shortcomings became clear. It had an extremely simple, even crude, control system that lacked the power-boosted controls of American aircraft. The F-4's twin engines were so powerful it could accelerate out of range of the MiG-17's guns in thirty seconds. It was important for the F-4 to keep its distance from the MiG-17. As long as the F-4 was one and a half miles from the MiG-17, it was outside the reach of the Soviet fighter's guns, but the MiG was within reach of the F-4's missiles.

The data from the HAVE DOUGHNUT and HAVE DRILL tests were provided to the newly formed Top Gun school at NAS Miramar. By 1970, the HAVE DRILL program was expanded; a few selected fleet F-4 crews were given the chance to fight the MiGs. The most important result of Project HAVE DRILL is that no Navy pilot who flew in the project defeated the MiG-17 Fresco in the first engagement. The HAVE DRILL dogfights were by invitation only. The other pilots based at Nellis Air Force Base were not to know about the U.S.-operated MiGs. To prevent any sightings, the airspace above the Groom Lake range was closed. On aeronautical maps, the exercise area was marked in red ink. The forbidden zone became known as "Red Square".

During the remainder of the Vietnam War, the Navy kill ratio climbed to 8.33 to 1. In contrast, the Air Force rate improved only slightly to 2.83 to 1. The reason for this difference was Top Gun. The Navy had revitalized its air combat training, while the Air Force had stayed stagnant. Most of the Navy MiG kills were by Top Gun graduates.

In May 1973, Project HAVE IDEA was formed, which took over from the older HAVE DOUGHNUT, HAVE FERRY and HAVE DRILL projects, and the project was transferred to the Tonopah Test Range Airport. At Tonopah, testing of foreign technology aircraft continued and expanded throughout the 1970s and 1980s.

Area 51 also hosted another foreign materiel evaluation program called HAVE GLIB. This involved testing Soviet tracking and missile control radar systems. A complex of actual and replica Soviet-type threat systems began to grow around "Slater Lake", a mile northwest of the main base, along with an acquired Soviet "Barlock" search radar placed at Tonopah Air Force Station. They were arranged to simulate a Soviet-style air defense complex.

The Air Force began funding improvements to Area 51 in 1977 under project SCORE EVENT. In 1979, the CIA transferred jurisdiction of the Area 51 site to the Air Force Flight Test Center at Edwards AFB, California. Sam Mitchell, the last CIA commander of Area 51, relinquished command to USAF Lt. Col. Larry D. McClain.

In 2017, a USAF aircraft crashed at the site, killing the pilot, Lt. Colonel Eric "Doc" Schultz. The USAF refused to release further information regarding the crash. In 2022, unconfirmed reports emerged that the crash involved an SU-27 that was part of the classified Foreign Materials Exploitation program. The reports claimed that the aircraft suffered a technical issue that resulted in both crew members ejecting from the aircraft, resulting in the death of Schultz.

Have Blue/F-117 program
The Lockheed Have Blue prototype stealth fighter (a smaller proof-of-concept model of the F-117 Nighthawk) first flew at Groom in December 1977.

In 1978, the Air Force awarded a full-scale development contract for the F-117 to Lockheed Corporation's Advanced Development Projects. On 17 January 1981 the Lockheed test team at Area 51 accepted delivery of the first full-scale development (FSD) prototype 79–780, designated YF-117A. At 6:05 am on 18 June 1981 Lockheed Skunk Works test pilot Hal Farley lifted the nose of YF-117A 79–780 off the runway of Area 51.

Meanwhile, Tactical Air Command (TAC) decided to set up a group-level organization to guide the F-117A to an initial operating capability. That organization became the 4450th Tactical Group (Initially designated "A Unit"), which officially activated on 15 October 1979 at Nellis AFB, Nevada, although the group was physically located at Area 51. The 4450th TG also operated the A-7D Corsair II as a surrogate trainer for the F-117A, and these operations continued until 15 October 1982 under the guise of an avionics test mission.

Flying squadrons of the 4450th TG were the 4450th Tactical Squadron (Initially designated "I Unit") activated on 11 June 1981, and 4451st Tactical Squadron (Initially designated "P Unit") on 15 January 1983. The 4450th TS, stationed at Area 51, was the first F-117A squadron, while the 4451st TS was stationed at Nellis AFB and was equipped with A-7D Corsair IIs painted in a dark motif, tail coded "LV". Lockheed test pilots put the YF-117 through its early paces. A-7Ds were used for pilot training before any F-117As had been delivered by Lockheed to Area 51, later the A-7D's were used for F-117A chase testing and other weapon tests at the Nellis Range. On 15 October 1982, Major Alton C. Whitley Jr. became the first USAF 4450th TG pilot to fly the F-117A.

Although ideal for testing, Area 51 was not a suitable location for an operational group, so a new covert base had to be established for F-117 operations. Tonopah Test Range Airport was selected for operations of the first USAF F-117 unit, the 4450th Tactical Group (TG). From October 1979, the Tonopah Airport base was reconstructed and expanded. The 6,000-foot runway was lengthened to 10,000 feet. Taxiways, a concrete apron, a large maintenance hangar, and a propane storage tank were added.

By early 1982, four more YF-117As were operating at the base. After finding a large scorpion in their offices, the testing team (Designated "R Unit") adopted it as their mascot and dubbed themselves the "Baja Scorpions". Testing of a series of ultra-secret prototypes continued at Area 51 until mid-1981 when testing transitioned to the initial production of F-117 stealth fighters. The F-117s were moved to and from Area 51 by C-5 during darkness to maintain security. The aircraft were defueled, disassembled, cradled, and then loaded aboard the C-5 at night, flown to Lockheed, and unloaded at night before reassembly and flight testing. Groom performed radar profiling, F-117 weapons testing, and training of the first group of frontline USAF F-117 pilots.

While the "Baja Scorpions" were working on the F-117, there was also another group at work in secrecy, known as "the Whalers" working on Tacit Blue. A fly-by-wire technology demonstration aircraft with curved surfaces and composite material, to evade radar, was a prototype, and never went into production. Nevertheless, this strange-looking aircraft was responsible for many of the stealth technology advances that were used on several other aircraft designs, and had a direct influence on the B-2; with the first flight of Tacit Blue being performed on 5February 1982, by Northrop Grumman test pilot, Richard G. Thomas.

Production FSD airframes from Lockheed were shipped to Area 51 for acceptance testing. As the Baja Scorpions tested the aircraft with functional check flights and L.O. verification, the operational airplanes were then transferred to the 4450th TG.

On 17 May 1982, the move of the 4450th TG from Groom Lake to Tonopah was initiated, with the final components of the move completed in early 1983. Production FSD airframes from Lockheed were shipped to Area 51 for acceptance testing. As the Baja Scorpions tested the aircraft with functional check flights and L.O. verification, the operational airplanes were then transferred to the 4450th TG at Tonopah.

The R-Unit was inactivated on 30 May 1989. Upon inactivation, the unit was reformed as Detachment 1, 57th Fighter Weapons Wing (FWW). In 1990, the last F-117A (843) was delivered from Lockheed. After completion of acceptance flights at Area 51 of this last new F-117A aircraft, the flight test squadron continued flight test duties of refurbished aircraft after modifications by Lockheed. In February/March 1992 the test unit moved from Area 51 to the USAF Palmdale Plant 42 and was integrated with the Air Force Systems Command 6510th Test Squadron. Some testing, especially RCS verification and other classified activity was still conducted at Area 51 throughout the operational lifetime of the F-117. The recently inactivated (2008) 410th Flight Test Squadron traces its roots, if not its formal lineage to the 4450th TG R-unit.

Later operations
Since the F-117 became operational in 1983, operations at Groom Lake have continued. The base and its associated runway system were expanded, including the expansion of housing and support facilities. In 1995, the federal government expanded the exclusionary area around the base to include nearby mountains that had hitherto afforded the only decent overlook of the base, prohibiting access to 3972 acre of land formerly administered by the Bureau of Land Management.

U.S. government's positions on Area 51
The United States government has provided minimal information regarding Area 51. The area surrounding the lake is permanently off-limits to both civilian and normal military air traffic. Security clearances are checked regularly; cameras and weaponry are not allowed. Even military pilots training in the NAFR risk disciplinary action if they stray into the exclusionary "box" surrounding Groom's airspace. Surveillance is supplemented using buried motion sensors. Area 51 is a common destination for Janet, a small fleet of passenger aircraft operated on behalf of the Air Force to transport military personnel, primarily from Harry Reid International Airport.

The United States Geological Survey (USGS) topographic map for the area only shows the long-disused Groom Mine, but USGS aerial photographs of the site in 1959 and 1968 were publicly available. A civil aviation chart published by the Nevada Department of Transportation shows a large restricted area, defined as part of the Nellis restricted airspace. The National Atlas shows the area as lying within the Nellis Air Force Base. There are higher resolution and newer images available from other satellite imagery providers, including Russian providers and the IKONOS. These show the runway markings, base facilities, aircraft, and vehicles.

In 1998 USAF officially acknowledged the site's existence. On 25 June 2013, the CIA released an official history of the U-2 and OXCART projects which acknowledged that the U-2 was tested at Area 51, in response to a Freedom of Information Act request submitted in 2005 by Jeffrey T. Richelson of George Washington University's National Security Archive. It contains numerous references to Area 51 and Groom Lake, along with a map of the area. Media reports stated that releasing the CIA history was the first governmental acknowledgement of Area 51's existence; rather, it was the first official acknowledgement of specific activity at the site.

Environmental lawsuit
In 1994, five unnamed civilian contractors and the widows of contractors Walter Kasza and Robert Frost sued the Air Force and the United States Environmental Protection Agency. They alleged that they had been present when large quantities of unknown chemicals had been burned in open pits and trenches at Groom. Rutgers University biochemists analyzed biopsies from the complainants and found high levels of dioxin, dibenzofuran, and trichloroethylene in their body fat. The complainants alleged that they had sustained skin, liver, and respiratory injuries due to their work at Groom and that this had contributed to the deaths of Frost and Kasza. The suit sought compensation for the injuries, claiming that the Air Force had illegally handled toxic materials and that the EPA had failed in its duty to enforce the Resource Conservation and Recovery Act which governs the handling of dangerous materials. They also sought detailed information about the chemicals, hoping that this would facilitate the medical treatment of survivors. Congressman Lee H. Hamilton, former chairman of the House Intelligence Committee, told 60 Minutes reporter Lesley Stahl, "The Air Force is classifying all information about Area 51 in order to protect themselves from a lawsuit."

The government invoked the State Secrets Privilege and petitioned U.S. District Judge Philip Pro to disallow disclosure of classified documents or examination of secret witnesses, claiming that this would expose classified information and threaten national security. Judge Pro rejected the government's argument, so President Bill Clinton issued a Presidential Determination exempting what it called "the Air Force's Operating Location Near Groom Lake, Nevada" from environmental disclosure laws. Consequently, Pro dismissed the suit due to lack of evidence. Jonathan Turley, the attorney who was handling the lawsuit, appealed to the U.S. Court of Appeals for the Ninth Circuit on the grounds that the government was abusing its power to classify material. Secretary of the Air Force Sheila E. Widnall filed a brief which stated that disclosures of the materials present in the air and water near Groom "can reveal military operational capabilities or the nature and scope of classified operations." The Ninth Circuit rejected Turley's appeal and the U.S. Supreme Court refused to hear it, putting an end to the complainants' case.

The President annually issues a determination continuing the Groom exception  which is the only formal recognition that the government has ever given that Groom Lake is more than simply another part of the Nellis complex. An unclassified memo on the safe handling of F-117 Nighthawk material was posted on an Air Force web site in 2005. This discussed the same materials for which the complainants had requested information, which the government had claimed was classified. The memo was removed shortly after journalists became aware of it.

Civil aviation identification
In December 2007, airline pilots noticed that the base had appeared in their aircraft navigation systems' latest Jeppesen database revision with the ICAO airport identifier code of KXTA and listed as "Homey Airport". The probably inadvertent release of the airport data led to advice by the Aircraft Owners and Pilots Association (AOPA) that student pilots should be explicitly warned about KXTA, not to consider it as a waypoint or destination for any flight even though it now appears in public navigation databases.

Security

The perimeter of the base is marked out by orange posts and patrolled by guards in white pickup trucks and camouflage fatigues. The guards are popularly referred to as "camo dudes" by enthusiasts. The guards will not answer questions about their employers; however, according to the New York Daily News, there are indications they are employed through a contractor such as AECOM. Signage around the base perimeter advises that deadly force is authorized against trespassers.

Technology is also heavily used to maintain the border of the base; this includes surveillance cameras and motion detectors. Some of these motion detectors are placed some distance away from the base on public land to notify guards of people approaching.

1974 Skylab photography
Dwayne A. Day published "Astronauts and Area 51: the Skylab Incident" in The Space Review in January 2006. It was based on a memo written in 1974 to CIA director William Colby by an unknown CIA official. The memo reported that astronauts on board Skylab had inadvertently photographed a certain location: "There were specific instructions not to do this. [redacted] was the only location which had such an instruction."

The name of the location was obscured, but the context led Day to believe that the subject was Groom Lake. Day wrote that "the CIA considered no other spot on Earth to be as sensitive as Groom Lake". Even within the agency's National Photographic Interpretation Center that handled classified reconnaissance satellite photographs, images of the site were removed from film rolls and stored separately as not all photo interpreters had security clearance for the information. The memo details debate between federal agencies regarding whether the images should be classified, with Department of Defense agencies arguing that it should and NASA and the State Department arguing that it should not be classified. The memo itself questions the legality of retroactively classifying unclassified images.

The memo includes handwritten remarks, apparently by Director of Central Intelligence Colby:

"[Secretary of State Rusk] did raise it—said State Dept. people felt strongly. But he inclined leave decision to me (DCI)—I confessed some question over need to protect since:
 * 1) USSR has it from own sats
 * 2) What really does it reveal?
 * 3) If exposed, don't we just say classified USAF work is done there?"

The declassified documents do not disclose the outcome of discussions regarding the Skylab imagery. The debate proved moot, as the photograph appeared in the Federal Government's Archive of Satellite Imagery along with the remaining Skylab photographs.

2019 shooting incident
On 28 January 2019, an unidentified man drove through a security checkpoint near Mercury, Nevada, in an apparent attempt to enter the base. After an 8 mi vehicle pursuit by base security, the man exited his vehicle carrying a "cylindrical object" and was shot dead by NNSS security officers and sheriff's deputies after refusing to obey requests to halt. There were no other injuries reported.

UFO and other conspiracy theories

Area 51 has become a focus of modern conspiracy theories due to its secretive nature and connection to classified aircraft research. Theories include:
 * The storage, examination, and reverse engineering of crashed alien spacecraft, including material supposedly recovered at Roswell, the study of their occupants, and the manufacture of aircraft based on alien technology
 * Meetings or joint undertakings with extraterrestrials
 * The development of exotic energy weapons for the Strategic Defense Initiative (SDI) or other weapons programs
 * The development of weather control
 * The development of time travel and teleportation technology
 * The development of exotic propulsion systems related to the Aurora Program
 * Activities related to the conspiracy theory of a one-world government

Many of the hypotheses concern underground facilities at Groom or at Papoose Lake (also known as "S-4 location"), 8.5 mi south, and include claims of a transcontinental underground railroad system, a disappearing airstrip nicknamed the "Cheshire Airstrip", after Lewis Carroll's Cheshire cat, which briefly appears when water is sprayed onto its camouflaged asphalt, and engineering based on alien technology.

In the mid-1950s, civilian aircraft flew under 20,000 feet while military aircraft flew up to 40,000 feet. The U-2 began flying above 60,000 feet and there was an increasing number of UFO sighting reports. Sightings occurred most often during early evening hours, when airline pilots flying west saw the U-2's silver wings reflect the setting sun, giving the aircraft a "fiery" appearance. Many sighting reports came to the Air Force's Project Blue Book, which investigated UFO sightings, through air-traffic controllers and letters to the government. The project checked U-2 and later OXCART flight records to eliminate the majority of UFO reports that it received during the late 1950s and 1960s, although it could not reveal to the letter writers the truth behind what they saw. Similarly, veterans of experimental projects such as OXCART at Area 51 agree that their work inadvertently prompted many of the UFO sightings and other rumors: "The shape of OXCART was unprecedented, with its wide, disk-like fuselage designed to carry vast quantities of fuel. Commercial pilots cruising over Nevada at dusk would look up and see the bottom of OXCART whiz by at 2,000-plus mph. The aircraft's titanium body, moving as fast as a bullet, would reflect the sun's rays in a way that could make anyone think, UFO."

They believe that the rumors helped maintain secrecy over Area 51's actual operations. The veterans deny the existence of a vast underground railroad system, although many of Area 51's operations did occur underground.

Bob Lazar claimed in 1989 that he had worked at Area 51's "Sector Four (S-4)", said to be located underground inside the Papoose Range near Papoose Lake. He claimed that he was contracted to work with alien spacecraft that the government had in its possession. Similarly, the 1996 documentary Dreamland directed by Bruce Burgess included an interview with a 71-year-old mechanical engineer who claimed to be a former employee at Area 51 during the 1950s. His claims included that he had worked on a "flying disc simulator" which had been based on a disc originating from a crashed extraterrestrial craft and was used to train pilots. He also claimed to have worked with an extraterrestrial being named "J-Rod" and described as a "telepathic translator". In 2004, Dan Burisch (pseudonym of Dan Crain) claimed to have worked on cloning alien viruses at Area 51, also alongside the alien named "J-Rod". Burisch's scholarly credentials are the subject of much debate, as he was apparently working as a Las Vegas parole officer in 1989 while also earning a PhD at State University of New York (SUNY).

In July 2019, more than 2,000,000 people responded to a joke proposal to storm Area 51 which appeared in an anonymous Facebook post. The event, scheduled for 20 September 2019, was billed as "Storm Area 51, They Can't Stop All of Us", an attempt to "see them aliens". Air Force spokeswoman Laura McAndrews said the government "would discourage anyone from trying to come into the area where we train American armed forces". Two music festivals in rural Nevada, AlienStock and Storm Area 51 Basecamp, were subsequently organized to capitalize on the popularity of the original Facebook event. Between 1,500 and 3,000 people showed up at the festivals, while over 150 people made the journey over several miles of rough roads to get near the gates to Area 51. Seven people were reportedly arrested at the event.

In popular culture
Because of Area 51's prominence in relation to aliens and conspiracy theories, it has often been used as a setting and theme in popular culture, especially in science fiction works involving aliens.

title: Area 51


text:
Audio signal processing

Audio signal processing is a subfield of signal processing that is concerned with the electronic manipulation of audio signals. Audio signals are electronic representations of sound waves—longitudinal waves which travel through air, consisting of compressions and rarefactions. The energy contained in audio signals or sound power level is typically measured in decibels. As audio signals may be represented in either digital or analog format, processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on its digital representation.

History
The motivation for audio signal processing began at the beginning of the 20th century with inventions like the telephone, phonograph, and radio that allowed for the transmission and storage of audio signals. Audio processing was necessary for early radio broadcasting, as there were many problems with studio-to-transmitter links. The theory of signal processing and its application to audio was largely developed at Bell Labs in the mid 20th century. Claude Shannon and Harry Nyquist's early work on communication theory, sampling theory and pulse-code modulation (PCM) laid the foundations for the field. In 1957, Max Mathews became the first person to synthesize audio from a computer, giving birth to computer music.

Major developments in digital audio coding and audio data compression include differential pulse-code modulation (DPCM) by C. Chapin Cutler at Bell Labs in 1950, linear predictive coding (LPC) by Fumitada Itakura (Nagoya University) and Shuzo Saito (Nippon Telegraph and Telephone) in 1966, adaptive DPCM (ADPCM) by P. Cummiskey, Nikil S. Jayant and James L. Flanagan at Bell Labs in 1973, discrete cosine transform (DCT) coding by Nasir Ahmed, T. Natarajan and K. R. Rao in 1974, and modified discrete cosine transform (MDCT) coding by J. P. Princen, A. W. Johnson and A. B. Bradley at the University of Surrey in 1987. LPC is the basis for perceptual coding and is widely used in speech coding, while MDCT coding is widely used in modern audio coding formats such as MP3 and Advanced Audio Coding (AAC).

Analog
An analog audio signal is a continuous signal represented by an electrical voltage or current that is analogous to the sound waves in the air. Analog signal processing then involves physically altering the continuous signal by changing the voltage or current or charge via electrical circuits.

Historically, before the advent of widespread digital technology, analog was the only method by which to manipulate a signal. Since that time, as computers and software have become more capable and affordable, digital signal processing has become the method of choice. However, in music applications, analog technology is often still desirable as it often produces nonlinear responses that are difficult to replicate with digital filters.

Digital
A digital representation expresses the audio waveform as a sequence of symbols, usually binary numbers. This permits signal processing using digital circuits such as digital signal processors, microprocessors and general-purpose computers. Most modern audio systems use a digital approach as the techniques of digital signal processing are much more powerful and efficient than analog domain signal processing.

Applications
Processing methods and application areas include storage, data compression, music information retrieval, speech processing, localization, acoustic detection, transmission, noise cancellation, acoustic fingerprinting, sound recognition, synthesis, and enhancement (e.g. equalization, filtering, level compression, echo and reverb removal or addition, etc.).

Audio broadcasting
Audio signal processing is used when broadcasting audio signals in order to enhance their fidelity or optimize for bandwidth or latency. In this domain, the most important audio processing takes place just before the transmitter. The audio processor here must prevent or minimize overmodulation, compensate for non-linear transmitters (a potential issue with medium wave and shortwave broadcasting), and adjust overall loudness to the desired level.

Active noise control
Active noise control is a technique designed to reduce unwanted sound. By creating a signal that is identical to the unwanted noise but with the opposite polarity, the two signals cancel out due to destructive interference.

Audio synthesis
Audio synthesis is the electronic generation of audio signals. A musical instrument that accomplishes this is called a synthesizer. Synthesizers can either imitate sounds or generate new ones. Audio synthesis is also used to generate human speech using speech synthesis.

Audio effects
Audio effects alter the sound of a musical instrument or other audio source. Common effects include distortion, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects, such as reverb and delay, which create echoing sounds and emulate the sound of different spaces.

Musicians, audio engineers and record producers use effects units during live performances or in the studio, typically with electric guitar, bass guitar, electronic keyboard or electric piano. While effects are most frequently used with electric or electronic instruments, they can be used with any audio source, such as acoustic instruments, drums, and vocals.

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

title: Audio signal processing


text:
Amdahl's law

In computer architecture, Amdahl's law (or Amdahl's argument ) is a formula which gives the theoretical speedup in latency of the execution of a task at fixed workload that can be expected of a system whose resources are improved. It states that "the overall performance improvement gained by optimizing a single part of a system is limited by the fraction of time that the improved part is actually used". It is named after computer scientist Gene Amdahl, and was presented at the American Federation of Information Processing Societies (AFIPS) Spring Joint Computer Conference in 1967.

Amdahl's law is often used in parallel computing to predict the theoretical speedup when using multiple processors. For example, if a program needs 20 hours to complete using a single thread, but a one-hour portion of the program cannot be parallelized, therefore only the remaining 19 hours' (p = 0.95) execution time can be parallelized, then regardless of how many threads are devoted to a parallelized execution of this program, the minimum execution time is always more than 1 hour. Hence, the theoretical speedup is less than 20 times the single thread performance, $$\left(\dfrac{1}{1-p} = 20\right)$$.

Definition
Amdahl's law can be formulated in the following way:

 * $$S_\text{latency}(s) = \frac 1 {(1 - p) + \frac p s}$$

where
 * Slatency is the theoretical speedup of the execution of the whole task;
 * s is the speedup of the part of the task that benefits from improved system resources;
 * p is the proportion of execution time that the part benefiting from improved resources originally occupied.

Furthermore,

\begin{cases} S_\text{latency}(s) \leq \dfrac 1 {1 - p} \\[8pt] \lim\limits_{s \to \infty} S_\text{latency}(s) = \dfrac 1 {1 - p}. \end{cases} $$

shows that the theoretical speedup of the execution of the whole task increases with the improvement of the resources of the system and that regardless of the magnitude of the improvement, the theoretical speedup is always limited by the part of the task that cannot benefit from the improvement.

Amdahl's law applies only to the cases where the problem size is fixed. In practice, as more computing resources become available, they tend to get used on larger problems (larger datasets), and the time spent in the parallelizable part often grows much faster than the inherently serial work. In this case, Gustafson's law gives a less pessimistic and more realistic assessment of the parallel performance.

Derivation
A task executed by a system whose resources are improved compared to an initial similar system can be split up into two parts:

 * a part that does not benefit from the improvement of the resources of the system;
 * a part that benefits from the improvement of the resources of the system.

An example is a computer program that processes files. A part of that program may scan the directory of the disk and create a list of files internally in memory. After that, another part of the program passes each file to a separate thread for processing. The part that scans the directory and creates the file list cannot be sped up on a parallel computer, but the part that processes the files can.

The execution time of the whole task before the improvement of the resources of the system is denoted as $$ T $$. It includes the execution time of the part that would not benefit from the improvement of the resources and the execution time of the one that would benefit from it. The fraction of the execution time of the task that would benefit from the improvement of the resources is denoted by $$ p $$. The one concerning the part that would not benefit from it is therefore $ 1 - p $. Then:

 * $$T = (1 - p)T + pT.$$

It is the execution of the part that benefits from the improvement of the resources that is accelerated by the factor $$ s $$ after the improvement of the resources. Consequently, the execution time of the part that does not benefit from it remains the same, while the part that benefits from it becomes:

 * $$\frac{p}{s}T.$$

The theoretical execution time $$ T (s) $$ of the whole task after the improvement of the resources is then:

 * $$T(s) = (1 - p)T + \frac p s T.$$

Amdahl's law gives the theoretical speedup in latency of the execution of the whole task at fixed workload $$ W $$, which yields
 * $$S_\text{latency}(s) = \frac{TW}{T(s)W} = \frac{T}{T(s)} = \frac 1 {1 - p + \frac p s}.$$

Parallel programs
If 30% of the execution time may be the subject of a speedup, p will be 0.3; if the improvement makes the affected part twice as fast, s will be 2. Amdahl's law states that the overall speedup of applying the improvement will be:

 * $$S_\text{latency} = \frac{1}{1 - p + \frac{p}{s}} = \frac 1 {1 - 0.3 + \frac {0.3} 2} = 1.18.$$

For example, assume that we are given a serial task which is split into four consecutive parts, whose percentages of execution time are p1 = 0.11, p2 = 0.18, p3 = 0.23, and p4 = 0.48 respectively. Then we are told that the 1st part is not sped up, so s1 = 1, while the 2nd part is sped up 5 times, so s2 = 5, the 3rd part is sped up 20 times, so s3 = 20, and the 4th part is sped up 1.6 times, so s4 = 1.6. By using Amdahl's law, the overall speedup is
 * $$S_\text{latency} = \frac{1}{\frac{p1}{s1} + \frac{p2}{s2} + \frac{p3}{s3} + \frac{p4}{s4}} = \frac{1}{\frac{0.11}{1} + \frac{0.18}{5} + \frac{0.23}{20} + \frac{0.48}{1.6}} = 2.19.$$

Notice how the 5 times and 20 times speedup on the 2nd and 3rd parts respectively don't have much effect on the overall speedup when the 4th part (48% of the execution time) is accelerated by only 1.6 times.

Serial programs

For example, with a serial program in two parts A and B for which TA = 3 s and TB = 1 s,

 * if part B is made to run 5 times faster, that is s = 5 and p = TB/(TA + TB) = 0.25, then $$S_\text{latency} = \frac 1 {1 - 0.25 + \frac{0.25}{5}} = 1.25;$$
 * if part A is made to run 2 times faster, that is s = 2 and p = TA/(TA + TB) = 0.75, then $$S_\text{latency} = \frac 1 {1 - 0.75 + \frac{0.75}{2}} = 1.60.$$

Therefore, making part A to run 2 times faster is better than making part B to run 5 times faster. The percentage improvement in speed can be calculated as
 * $$\text{percentage improvement} = 100 \left(1 - \frac 1 {S_\text{latency}}\right).$$

 * Improving part A by a factor of 2 will increase overall program speed by a factor of 1.60, which makes it 37.5% faster than the original computation.
 * However, improving part B by a factor of 5, which presumably requires more effort, will achieve an overall speedup factor of 1.25 only, which makes it 20% faster.

Optimizing the sequential part of parallel programs
If the non-parallelizable part is optimized by a factor of $ O $, then

 * $$T(O,s) = (1 - p)\frac{T}{O} + \frac{p}{s} T.$$

It follows from Amdahl's law that the speedup due to parallelism is given by
 * $$S_\text{latency}(O,s) = \frac{T(O)}{T(O,s)} = \frac {(1 - p)\frac{1}{O} + {p} } {\frac{1 - p}{O} + \frac p s}.$$

When $$s=1$$, we have $$S_\text{latency}(O,s)=1$$, meaning that the speedup is measured with respect to the execution time after the non-parallelizable part is optimized.

When $$s=\infty$$,
 * $$S_\text{latency}(O,\infty) = \frac{T(O)}{T(O,s)} = \frac {(1 - p)\frac{1}{O} + {p} } {\frac{1 - p}{O} + \frac p s}= 1 + \frac{p}{1-p}O.$$

If $$1-p=0.4$$, $$O=2$$ and $$s=5$$, then:

 * $$S_\text{latency}(O,s) = \frac{T(O)}{T(O,s)} = \frac{ {0.4} \frac{1}{2} + 0.6} {\frac{0.4}{2} + \frac{0.6}{5} }  = 2.5.$$

Transforming sequential parts of parallel programs into parallelizable
Next, we consider the case wherein the non-parallelizable part is reduced by a factor of $ O' $, and the parallelizable part is correspondingly increased. Then

 * $$T'(O',s) = \frac{1 - p}{O'} T + \left(1-\frac{1-p}{O'}\right) \frac{T}{s}.$$

It follows from Amdahl's law that the speedup due to parallelism is given by
 * $$S'_\text{latency}(O',s) = \frac{T'(O')}{T'(O',s)} = \frac { 1 } {  \frac{1 - p}{O'} + \left(1-\frac{1-p}{O'}\right) \frac{1}{s}}.$$

Relation to the law of diminishing returns
Amdahl's law is often conflated with the law of diminishing returns, whereas only a special case of applying Amdahl's law demonstrates law of diminishing returns. If one picks optimally (in terms of the achieved speedup) what is to be improved, then one will see monotonically decreasing improvements as one improves. If, however, one picks non-optimally, after improving a sub-optimal component and moving on to improve a more optimal component, one can see an increase in the return. Note that it is often rational to improve a system in an order that is "non-optimal" in this sense, given that some improvements are more difficult or require larger development time than others.

Amdahl's law does represent the law of diminishing returns if one is considering what sort of return one gets by adding more processors to a machine, if one is running a fixed-size computation that will use all available processors to their capacity. Each new processor added to the system will add less usable power than the previous one. Each time one doubles the number of processors the speedup ratio will diminish, as the total throughput heads toward the limit of 1/(1 − p).

This analysis neglects other potential bottlenecks such as memory bandwidth and I/O bandwidth. If these resources do not scale with the number of processors, then merely adding processors provides even lower returns.

An implication of Amdahl's law is that to speed up real applications which have both serial and parallel portions, heterogeneous computing techniques are required. There are novel speedup and energy consumption models based on a more general representation of heterogeneity, referred to as the normal form heterogeneity, that support a wide range of heterogeneous many-core architectures. These modelling methods aim to predict system power efficiency and performance ranges, and facilitates research and development at the hardware and system software levels.

title: Amdahl's law


text:
April 27

Pre-1600

 * 247 – Philip the Arab marks the millennium of Rome with a celebration of the ludi saeculares.
 * 395 – Emperor Arcadius marries Aelia Eudoxia, daughter of the Frankish general Flavius Bauto. She becomes one of the more powerful Roman empresses of Late Antiquity.
 * 711 – Islamic conquest of Hispania: Moorish troops led by Tariq ibn Ziyad land at Gibraltar to begin their invasion of the Iberian Peninsula (Al-Andalus).
 * 1296 – First War of Scottish Independence: John Balliol's Scottish army is defeated by an English army commanded by John de Warenne, 6th Earl of Surrey at the Battle of Dunbar.
 * 1509 – Pope Julius II places the Italian state of Venice under interdict.
 * 1521 – Battle of Mactan: Explorer Ferdinand Magellan is killed by natives in the Philippines led by chief Lapulapu.
 * 1539 – Official founding of the city of Bogotá, New Granada (nowadays Colombia), by Nikolaus Federmann and Sebastián de Belalcázar.
 * 1565 – Cebu is established becoming the first Spanish settlement in the Philippines.
 * 1595 – The relics of Saint Sava are incinerated in Belgrade on the Vračar plateau by Ottoman Grand Vizier Sinan Pasha; the site of the incineration is now the location of the Church of Saint Sava, one of the largest Orthodox churches in the world

1601–1900

 * 1650 – The Battle of Carbisdale: A Royalist army from Orkney invades mainland Scotland but is defeated by a Covenanter army.
 * 1667 – Blind and impoverished, John Milton sells Paradise Lost to a printer for £10, so that it could be entered into the Stationers' Register.
 * 1805 – First Barbary War: United States Marines and Berbers attack the Tripolitan city of Derna (The "shores of Tripoli" part of the Marines' Hymn).
 * 1813 – War of 1812: American troops capture York, the capital of Upper Canada, in the Battle of York.
 * 1861 – American President Abraham Lincoln suspends the writ of habeas corpus.

1901–present

 * 1906 – The State Duma of the Russian Empire meets for the first time.
 * 1909 – Sultan of Ottoman Empire Abdul Hamid II is overthrown, and is succeeded by his brother, Mehmed V.
 * 1911 – The Second Canton Uprising took place in Guangzhou, Qing China but was suppressed.
 * 1927 – Carabineros de Chile (Chilean national police force and gendarmerie) are created.
 * 1936 – The United Auto Workers (UAW) gains autonomy from the American Federation of Labor.
 * 1941 – World War II: German troops enter Athens.
 * 1945 – World War II: The last German formations withdraw from Finland to Norway. The Lapland War and thus, World War II in Finland, comes to an end and the Raising the Flag on the Three-Country Cairn photograph is taken.
 * 1945  – World War II: Benito Mussolini is arrested by Italian partisans in Dongo, while attempting escape disguised as a German soldier.
 * 1953 – Operation Moolah offers $50,000 to any pilot who defects with a fully mission-capable Mikoyan-Gurevich MiG-15 to South Korea. The first pilot was to receive $100,000.
 * 1967 – Expo 67 officially opens in Montreal, Quebec, Canada with a large opening ceremony broadcast around the world. It opens to the public the next day.
 * 1974 – 109 people are killed in a plane crash near Pulkovo Airport.
 * 1976 – Thirty-seven people are killed when American Airlines Flight 625 crashes at Cyril E. King Airport in Saint Thomas, U.S. Virgin Islands.
 * 1978 – John Ehrlichman, a former aide to U.S. President Richard Nixon, is released from the Federal Correctional Institution, Safford, Arizona, after serving 18 months for Watergate-related crimes.
 * 1978  – The Saur Revolution begins in Afghanistan, ending the following morning with the murder of Afghan President Mohammed Daoud Khan and the establishment of the Democratic Republic of Afghanistan.
 * 1978  – Willow Island disaster: In the deadliest construction accident in United States history, 51 construction workers are killed when a cooling tower under construction collapses at the Pleasants Power Station in Willow Island, West Virginia.
 * 1986 – The city of Pripyat and surrounding areas are evacuated due to the Chernobyl disaster.
 * 1987 – The U.S. Department of Justice bars Austrian President Kurt Waldheim (and his wife, Elisabeth, who had also been a Nazi) from entering the US, charging that he had aided in the deportations and executions of thousands of Jews and others as a German Army officer during World War II.
 * 1989 – The April 27 demonstrations, student-led protests responding to the April 26 Editorial, during the Tiananmen Square protests of 1989.
 * 1992 – The Federal Republic of Yugoslavia, comprising Serbia and Montenegro, is proclaimed.
 * 1992  – Betty Boothroyd becomes the first woman to be elected Speaker of the British House of Commons in its 700-year history.
 * 1992  – The Russian Federation and 12 other former Soviet republics become members of the International Monetary Fund and the World Bank.
 * 1993 – Most of the Zambia national football team lose their lives in a plane crash off Libreville, Gabon en route to Dakar, Senegal to play a 1994 FIFA World Cup qualifying match against Senegal.
 * 1994 – South African general election: The first democratic general election in South Africa, in which black citizens could vote. The Interim Constitution comes into force.
 * 2005 – Airbus A380 aircraft has its maiden test flight.
 * 2006 – Construction begins on the Freedom Tower (later renamed One World Trade Center) in New York City.
 * 2007 – Estonian authorities remove the Bronze Soldier, a Soviet Red Army war memorial in Tallinn, amid political controversy with Russia.
 * 2007  – Israeli archaeologists discover the tomb of Herod the Great south of Jerusalem.
 * 2011 – The 2011 Super Outbreak devastates parts of the Southeastern United States, especially the states of Alabama, Mississippi, Georgia, and Tennessee. Two hundred five tornadoes touched down on April 27 alone, killing more than 300 and injuring hundreds more.
 * 2012 – At least four explosions hit the Ukrainian city of Dnipropetrovsk with at least 27 people injured.
 * 2018 – The Panmunjom Declaration is signed between North and South Korea, officially declaring their intentions to end the Korean conflict.
 * 2024 – The worst day of the tornado outbreak sequence of April 25–28, 2024, with 42 tornadoes, including one confirmed EF4 tornado, and two confirmed EF3 tornadoes, which killed 4 people in total.

Pre-1600

 * 85 BC – Decimus Junius Brutus Albinus, Roman politician and general (d. 43 BC)
 * 1468 – Frederick Jagiellon, Primate of Poland (d. 1503)
 * 1564 – Henry Percy, 9th Earl of Northumberland (d. 1632)
 * 1556 – François Béroalde de Verville, French writer (d. 1626)
 * 1593 – Mumtaz Mahal, Mughal empress buried at the Taj Mahal (d. 1631)

1601–1900

 * 1650 – Charlotte Amalie of Hesse-Kassel, Queen Consort of Denmark (1670-1699) (d. 1714)
 * 1654 – Charles Blount, English deist and philosopher (d. 1693)
 * 1701 – Charles Emmanuel III of Sardinia (d. 1773)
 * 1718 – Thomas Lewis, Irish-born American surveyor and lawyer (d. 1790)
 * 1748 – Adamantios Korais, Greek-French philosopher and scholar (d. 1833)
 * 1755 – Marc-Antoine Parseval, French mathematician and theorist (d. 1836)
 * 1759 – Mary Wollstonecraft, English philosopher, historian, and novelist (d. 1797)
 * 1788 – Charles Robert Cockerell, English architect, archaeologist, and writer (d. 1863)
 * 1791 – Samuel Morse, American painter and inventor, co-invented the Morse code (d. 1872)
 * 1812 – William W. Snow, American lawyer and politician (d. 1886)
 * 1812  – Friedrich von Flotow, German composer (d. 1883)
 * 1820 – Herbert Spencer, English biologist, anthropologist, sociologist, and philosopher (d. 1903)
 * 1822 – Ulysses S. Grant, American general and politician, 18th President of the United States (d. 1885)
 * 1840 – Edward Whymper, English-French mountaineer, explorer, author, and illustrator (d. 1911)
 * 1848 – Otto, King of Bavaria (d. 1916)
 * 1850 – Hans Hartwig von Beseler, German general and politician (d. 1921)
 * 1853 – Jules Lemaître, French playwright and critic (d. 1914)
 * 1857 – Theodor Kittelsen, Norwegian painter and illustrator (d. 1914)
 * 1861 – William Arms Fisher, American composer and music historian (d. 1948)
 * 1866 – Maurice Raoul-Duval, French polo player (d. 1916)
 * 1875 – Frederick Fane, Irish-born, English cricketer (d. 1960)
 * 1880 – Mihkel Lüdig, Estonian organist, composer, and conductor (d. 1958)
 * 1882 – Jessie Redmon Fauset, American author and poet (d. 1961)
 * 1887 – Warren Wood, American golfer (d. 1926)
 * 1888 – Florence La Badie, Canadian actress (d. 1917)
 * 1891 – Sergei Prokofiev, Russian pianist, composer, and conductor (d. 1953)
 * 1893 – Draža Mihailović, Serbian general (d. 1946)
 * 1893  – Allen Sothoron, American baseball player, coach, and manager (d. 1939)
 * 1894 – George Petty, American painter and illustrator (d. 1975)
 * 1894  – Nicolas Slonimsky, Russian pianist, composer, and conductor (d. 1995)
 * 1896 – Rogers Hornsby, American baseball player, coach, and manager (d. 1963)
 * 1896  – William Hudson, New Zealand-Australian engineer (d. 1978)
 * 1896  – Wallace Carothers, American chemist and inventor of nylon (d. 1937)
 * 1898 – Ludwig Bemelmans, Italian-American author and illustrator (d. 1962)
 * 1899 – Walter Lantz, American animator, producer, screenwriter, and actor (d. 1994)
 * 1900 – August Koern, Estonian politician and diplomat, Estonian Minister of Foreign Affairs in exile (d. 1989)

1901–present

 * 1902 – Tiemoko Garan Kouyaté, Malian educator and activist (d. 1942)
 * 1904 – Cecil Day-Lewis, Anglo-Irish poet and author (d. 1972)
 * 1904  – Nikos Zachariadis, Greek politician (d. 1973)
 * 1905 – John Kuck, American javelin thrower and shot putter (d. 1986)
 * 1906 – Yiorgos Theotokas, Greek author and playwright (d. 1966)
 * 1909 – Lim Bo Seng, Chinese businessman, resistance fighter of Force 136 and war hero of Singapore (d. 1944)
 * 1910 – Chiang Ching-kuo, Chinese politician, 3rd President of the Republic of China (d. 1988)
 * 1911 – Bruno Beger, German anthropologist and ethnologist (d. 2009)
 * 1911  – Chris Berger, Dutch sprinter and footballer (d. 1965)
 * 1912 – Jacques de Bourbon-Busset, French author and politician (d. 2001)
 * 1912  – Zohra Sehgal, Indian actress, dancer, and choreographer (d. 2014)
 * 1913 – Philip Abelson, American physicist and author (d. 2004)
 * 1913  – Irving Adler, American mathematician, author, and academic (d. 2012)
 * 1913  – Luz Long, German long jumper and soldier (d. 1943)
 * 1916 – Robert Hugh McWilliams, Jr., American sergeant, lawyer, and judge (d. 2013)
 * 1916  – Enos Slaughter, American baseball player and manager (d. 2002)
 * 1917 – Roman Matsov, Estonian violinist, pianist, and conductor (d. 2001)
 * 1918 – Sten Rudholm, Swedish lawyer and jurist (d. 2008)
 * 1920 – Guido Cantelli, Italian conductor (d. 1956)
 * 1920  – Mark Krasnosel'skii, Ukrainian mathematician and academic (d. 1997)
 * 1920  – James Robert Mann, American colonel, lawyer, and politician (d. 2010)
 * 1920  – Edwin Morgan, Scottish poet and translator (d. 2010)
 * 1921 – Robert Dhéry, French actor, director, and screenwriter (d. 2004)
 * 1922 – Jack Klugman, American actor (d. 2012)
 * 1922  – Sheila Scott, English nurse and pilot (d. 1988)
 * 1923 – Betty Mae Tiger Jumper, Seminole chief (d. 2011)
 * 1924 – Vernon B. Romney, American lawyer and politician, 14th Attorney General of Utah (d. 2013)
 * 1925 – Derek Chinnery, English broadcaster (d. 2015)
 * 1926 – Tim LaHaye, American minister, activist, and author (d. 2016)
 * 1926  – Basil A. Paterson, American lawyer and politician, 59th Secretary of State of New York (d. 2014)
 * 1926  – Alan Reynolds, English painter and educator (d. 2014)
 * 1927 – Coretta Scott King, African-American activist and author (d. 2006)
 * 1927  – Joe Moakley, American soldier, lawyer, and politician (d. 2001)
 * 1929 – Nina Ponomaryova, Russian discus thrower and coach (d. 2016)
 * 1931 – Igor Oistrakh, Ukrainian violinist and educator (d. 2021)
 * 1932 – Anouk Aimée, French actress (d. 2024)
 * 1932  – Pik Botha, South African lawyer, politician, and diplomat, 8th South African Ambassador to the United States (d. 2018)
 * 1932  – Casey Kasem, American disc jockey, radio celebrity, and voice actor; co-created American Top 40 (d. 2014)
 * 1932  – Chuck Knox, American football coach (d. 2018)
 * 1932  – Derek Minter, English motorcycle racer (d. 2015)
 * 1932  – Gian-Carlo Rota, Italian-American mathematician and philosopher (d. 1999)
 * 1933 – Peter Imbert, Baron Imbert, English police officer and politician, Lord Lieutenant for Greater London (d. 2017)
 * 1935 – Theodoros Angelopoulos, Greek director, producer, and screenwriter (d. 2012)
 * 1935  – Ron Morris, American pole vaulter and coach (d. 2024)
 * 1936 – Geoffrey Shovelton, English singer and illustrator (d. 2016)
 * 1937 – Sandy Dennis, American actress (d. 1992)
 * 1937  – Robin Eames, Irish Anglican archbishop
 * 1937  – Richard Perham, English biologist and academic (d. 2015)
 * 1938 – Earl Anthony, American bowler and sportscaster (d. 2001)
 * 1938  – Alain Caron, Canadian ice hockey player (d. 1986)
 * 1939 – Judy Carne, English actress and comedian (d. 2015)
 * 1939  – Stanisław Dziwisz, Polish cardinal
 * 1941 – Fethullah Gülen, Turkish preacher and theologian
 * 1941  – Dilip Kumar Chakrabarti, Indian archaeologist
 * 1941  – Lee Roy Jordan, American football player
 * 1942 – Ruth Glick, American author
 * 1942  – Jim Keltner, American drummer
 * 1943 – Helmut Marko, Austrian race car driver and manager
 * 1944 – Michael Fish, English meteorologist and journalist
 * 1944  – Cuba Gooding Sr., American singer (d. 2017)
 * 1944  – Herb Pedersen, American singer-songwriter and guitarist
 * 1945 – Martin Chivers, English footballer and manager
 * 1945  – Terry Willesee, Australian journalist and television host
 * 1945  – August Wilson, American author and playwright (d. 2005)
 * 1946 – Franz Roth, German footballer
 * 1947 – G. K. Butterfield, African-American soldier, lawyer, and politician
 * 1947  – Nick Greiner, Hungarian-Australian politician, 37th Premier of New South Wales
 * 1947  – Pete Ham, Welsh singer-songwriter and guitarist (d. 1975)
 * 1947  – Keith Magnuson, Canadian ice hockey player and coach (d. 2003)
 * 1947  – Ann Peebles, American soul singer-songwriter
 * 1948 – Frank Abagnale Jr., American security consultant and criminal
 * 1948  – Josef Hickersberger, Austrian footballer, coach, and manager
 * 1948  – Kate Pierson, American singer-songwriter and bass player
 * 1950 – Jaime Fresnedi, Filipino politician
 * 1951 – Ace Frehley, American guitarist and songwriter
 * 1952 – Larry Elder, American lawyer and talk show host
 * 1952  – George Gervin, American basketball player
 * 1952  – Ari Vatanen, Finnish race car driver and politician
 * 1953 – Arielle Dombasle, French-American actress and model
 * 1954 – Frank Bainimarama, Fijian commander and politician, 8th Prime Minister of Fiji
 * 1954  – Herman Edwards, American football player, coach, and sportscaster
 * 1954  – Mark Holden, Australian singer, actor, and lawyer
 * 1955 – Eric Schmidt, American engineer and businessman
 * 1956 – Bryan Harvey, American singer-songwriter and guitarist (d. 2006)
 * 1957 – Willie Upshaw, American baseball player and manager
 * 1959 – Sheena Easton, Scottish-American singer-songwriter, actress, and producer
 * 1959  – Marco Pirroni, English singer-songwriter, guitarist, and producer
 * 1960 – Mike Krushelnyski, Canadian ice hockey player and coach
 * 1961 – Andrew Schlafly, American lawyer and activist, founded Conservapedia
 * 1962 – Ángel Comizzo, Argentinian footballer and manager
 * 1962  – Seppo Räty, Finnish javelin thrower and coach
 * 1962  – Im Sang-soo, South Korean director and screenwriter
 * 1962  – Andrew Selous, English soldier and politician
 * 1963 – Russell T Davies, Welsh screenwriter and producer
 * 1965 – Anna Chancellor, English actress
 * 1966 – Yoshihiro Togashi, Japanese illustrator
 * 1967 – Willem-Alexander, King of the Netherlands
 * 1967  – Tommy Smith, Scottish saxophonist, composer, and educator
 * 1967  – Erik Thomson, Scottish-New Zealand actor
 * 1967  – Jason Whitlock, American football player and journalist
 * 1968 – Dana Milbank, American journalist and author
 * 1969 – Cory Booker, African-American lawyer and politician
 * 1969  – Darcey Bussell, English ballerina
 * 1972 – Nigel Barker, English photographer and author
 * 1973 – Sharlee D'Angelo, Swedish bass player and songwriter
 * 1973  – Sébastien Lareau, Canadian tennis player
 * 1974 – Frank Catalanotto, American baseball player
 * 1975 – Chris Carpenter, American baseball player
 * 1975  – Pedro Feliz, Dominican baseball player
 * 1975  – Kazuyoshi Funaki, Japanese ski jumper
 * 1976 – Isobel Campbell, Scottish singer-songwriter and cellist
 * 1976  – Sally Hawkins, English actress
 * 1976  – Walter Pandiani, Uruguayan footballer
 * 1979 – Vladimir Kozlov, Ukrainian actor and wrestler
 * 1980 – Sybille Bammer, Austrian tennis player
 * 1980  – Christian Lara, Ecuadorian footballer
 * 1983 – Ari Graynor, American actress and producer
 * 1984 – Pierre-Marc Bouchard, Canadian ice hockey player
 * 1984  – Patrick Stump, American musician, singer, and songwriter
 * 1985 – Meselech Melkamu, Ethiopian runner
 * 1986 – Jenna Coleman, English actress
 * 1986  – Dinara Safina, Russian tennis player
 * 1987 – Taylor Chorney, American ice hockey player
 * 1987  – William Moseley, English actor
 * 1987  – Wang Feifei, Chinese singer and actress
 * 1988 – Lizzo, American singer and rapper
 * 1988  – Semyon Varlamov, Russian ice hockey player
 * 1989 – Lars Bender, German footballer
 * 1989  – Sven Bender, German footballer
 * 1990 – Austin Dillon, American race car driver
 * 1991 – Lara Gut, Swiss skier
 * 1992 – Keenan Allen, American football player
 * 1994 – Corey Seager, American baseball player
 * 1995 – Nick Kyrgios, Australian tennis player
 * 1998 – Cristian Romero, Argentine footballer
 * 2003 – Xavier Worthy, American football player

Pre-1600

 * 630 – Ardashir III of Persia (b. 621)
 * 1160 – Rudolf I, Count of Bregenz (b. 1081)
 * 1272 – Zita, Italian saint (b. 1212)
 * 1321 – Nicolò Albertini, Italian cardinal statesman (b. c. 1250)
 * 1353 – Simeon of Moscow, Grand Prince of Moscow and Vladimir
 * 1403 – Maria of Bosnia, Countess of Helfenstein (b. 1335)
 * 1404 – Philip II, Duke of Burgundy (b. 1342)
 * 1463 – Isidore of Kiev (b. 1385)
 * 1521 – Ferdinand Magellan, Portuguese sailor and explorer (b. 1480)
 * 1599 – Maeda Toshiie, Japanese general (b. 1538)

1601–1900

 * 1605 – Pope Leo XI (b. 1535)
 * 1607 – Edward Cromwell, 3rd Baron Cromwell, Governor of Lecale (b. 1560)
 * 1613 – Robert Abercromby, Scottish priest and missionary (b. 1532)
 * 1656 – Jan van Goyen, Dutch painter and illustrator (b. 1596)
 * 1694 – John George IV, Elector of Saxony (b. 1668)
 * 1695 – John Trenchard, English politician, Secretary of State for the Northern Department (b. 1640)
 * 1702 – Jean Bart, French admiral (b. 1651)
 * 1782 – William Talbot, 1st Earl Talbot, English politician, Lord Steward of the Household (b. 1710)
 * 1813 – Zebulon Pike, American general and explorer (b. 1779)
 * 1873 – William Macready, English actor and manager (b. 1793)
 * 1882 – Ralph Waldo Emerson, American poet and philosopher (b. 1803)
 * 1893 – John Ballance, Irish-born New Zealand journalist and politician, 14th Prime Minister of New Zealand (b. 1839)
 * 1896 – Henry Parkes, English-Australian businessman and politician, 7th Premier of New South Wales (b. 1815)

1901–present

 * 1915 – John Labatt, Canadian businessman (b. 1838)
 * 1915  – Alexander Scriabin, Russian pianist and composer (b. 1872)
 * 1932 – Hart Crane, American poet (b. 1899)
 * 1936 – Karl Pearson, English mathematician and academic (b. 1857)
 * 1937 – Antonio Gramsci, Italian sociologist, linguist, and politician (b. 1891)
 * 1938 – Edmund Husserl, Czech mathematician and philosopher (b. 1859)
 * 1949 – Benjamin Faunce, American druggist and businessman (b. 1873)
 * 1952 – Guido Castelnuovo, Italian mathematician and statistician (b. 1865)
 * 1961 – Roy Del Ruth, American director, producer, and screenwriter (b. 1893)
 * 1962 – A. K. Fazlul Huq, Bangladeshi-Pakistani lawyer and politician, Pakistani Minister of the Interior (b. 1873)
 * 1965 – Edward R. Murrow, American journalist (b. 1908)
 * 1967 – William Douglas Cook, New Zealand farmer, founded the Eastwoodhill Arboretum (b. 1884)
 * 1969 – René Barrientos, Bolivian soldier, pilot, and politician, 55th President of Bolivia (b. 1919)
 * 1970 – Arthur Shields, Irish rebel and actor (b. 1896)
 * 1972 – Kwame Nkrumah, Ghanaian politician, 1st President of Ghana (b. 1909)
 * 1973 – Carlos Menditeguy, Argentinian race car driver and polo player (b. 1914)
 * 1977 – Stanley Adams, American actor and screenwriter (b. 1915)
 * 1988 – Fred Bear, American hunter and author (b. 1902)
 * 1989 – Konosuke Matsushita, Japanese businessman, founded Panasonic (b. 1894)
 * 1992 – Olivier Messiaen, French organist and composer (b. 1908)
 * 1992  – Gerard K. O'Neill, American physicist and astronomer (b. 1927)
 * 1995 – Katherine DeMille, Canadian-American actress (b. 1911)
 * 1995  – Willem Frederik Hermans, Dutch author, poet, and playwright (b. 1921)
 * 1996 – William Colby, American diplomat, 10th Director of Central Intelligence (b. 1920)
 * 1996  – Gilles Grangier, French director and screenwriter (b. 1911)
 * 1998 – John Bassett, Canadian journalist and politician (b. 1915)
 * 1998  – Carlos Castaneda, Peruvian-American anthropologist and author (b. 1925)
 * 1998  – Anne Desclos, French journalist and author (b. 1907)
 * 1998  – Browning Ross, American runner and soldier (b. 1924)
 * 1999 – Al Hirt, American trumpet player and bandleader (b. 1922)
 * 1999  – Dale C. Thomson, Canadian historian, author, and academic (b. 1923)
 * 1999  – Cyril Washbrook, English cricketer (b. 1914)
 * 2002 – George Alec Effinger, American author (b. 1947)
 * 2002  – Ruth Handler, American inventor and businesswoman, created the Barbie doll (b. 1916)
 * 2005 – Red Horner, Canadian ice hockey player (b. 1909)
 * 2006 – Julia Thorne, American author (b. 1944)
 * 2007 – Mstislav Rostropovich, Russian cellist and conductor (b. 1927)
 * 2009 – Frankie Manning, American dancer and choreographer (b. 1914)
 * 2009  – Woo Seung-yeon, South Korean model and actress (b. 1983)
 * 2009 – Feroz Khan (actor), Indian Actor, Film Director & Producer (b. 1939)
 * 2011 – Marian Mercer, American actress and singer (b. 1935)
 * 2012 – Daniel E. Boatwright, American soldier and politician (b. 1930)
 * 2012  – Bill Skowron, American baseball player (b. 1930)
 * 2013 – Aída Bortnik, Argentinian screenwriter (b. 1938)
 * 2013  – Lorraine Copeland, Scottish archaeologist (b. 1921)
 * 2013  – Antonio Díaz Jurado, Spanish footballer (b. 1969)
 * 2013  – Jérôme Louis Heldring, Dutch journalist and author (b. 1917)
 * 2013  – Aloysius Jin Luxian, Chinese bishop (b. 1916)
 * 2013  – Mutula Kilonzo, Kenyan lawyer and politician, Kenyan Minister of Justice (b. 1948)
 * 2014 – Yigal Arnon, Israeli lawyer (b. 1929)
 * 2014  – Vujadin Boškov, Serbian footballer, coach, and manager (b. 1931)
 * 2014  – Daniel Colchico, American football player and coach (b. 1935)
 * 2014  – Harry Firth, Australian race car driver and manager (b. 1918)
 * 2015 – Gene Fullmer, American boxer (b. 1931)
 * 2015  – Verne Gagne, American football player, wrestler, and trainer (b. 1926)
 * 2015  – Alexander Rich, American biologist, biophysicist, and academic (b. 1924)
 * 2017 – Vinod Khanna, Indian actor, producer and politician (b. 1946)
 * 2017  – Sadanoyama Shinmatsu, Japanese sumo wrestler (b. 1938)
 * 2021 – Manoj Das, Indian writer (b. 1934)
 * 2022 – Liao Guoxun, Chinese politician (b. 1963)
 * 2023 – Jerry Springer, American politician and actor (b. 1944)
 * 2024 – C. J. Sansom, British author (b. 1952)

Holidays and observances

 * Christian feast days:
 * Anthimus of Nicomedia
 * Assicus
 * Floribert of Liège
 * John of Constantinople
 * Liberalis of Treviso
 * Pollio
 * Virgin of Montserrat
 * Zita
 * Origen Adamantius
 * April 27 (Eastern Orthodox liturgics)
 * Day of Russian Parliamentarism (Russia)
 * Day of the Uprising Against the Occupying Forces (Slovenia)
 * Flag Day (Moldova)
 * Freedom Day (South Africa)
 * Independence Day, celebrates the independence of Sierra Leone from United Kingdom in 1961.
 * Independence Day, celebrates the independence of Togo from France in 1960.
 * King's Day (Netherlands, Aruba, Curaçao, Sint Maarten) (celebrated on April 26 if April 27 falls on a Sunday)
 * National Veterans' Day (Finland)

title: April 27


text:
Talk:Attila/Archive 1

A half-million strong army? Without knowing specifically, I'm assuming this is one of the invariable overestimates of armies made by contemporaries during classical times. -- Paul Drye

 * you're probably right, but the article does say "reputed to be". Perhaps it can be toned down further - clasqm

 * I added the "reputed to be" part, which works me as a result :) If someone actually knows the source of the figure and wants to discuss it and its likelihood, I'd be all for it, though. --Paul Drye

Attila seems to be remembered very negatively in some European countries today, while in some others (including Hungary), he seems to be remembered as a hero. It would be useful if a specialist could elaborate on this topic in the article. olivier 02:38 Nov 12, 2002 (UTC)

I heard Attila teh Hun died by bursting an artery whilst bedding a virgin. -fonzy

Actually, nobody knows, how he died. The author of this article seems certain that it was nasal hemorrhage, but there are stories, that this same virgin assassinated him - UrmasU

Was his original name not Avitohol? And Attila was that given to him, meaning 'little father' in the Gothic?

Also, he did appoint a successor, his eldest son Ellak, and it was only later when his other sons, Dengizik and Ernak, began to rebel against Ellak that the empire began to disintegrate.

title: Talk:Attila/Archive 1