Headlines from the Long Beach Press-Telegram of 25 February 1942 describing the five-hour air alarm earlier that morning.

A photograph showing searchlight beams converging on one of the fifteen aerial intruders seen over Culver City, Los Angeles. The blobs of light are probably bursts of anti-aircraft rounds. (Image enhanced by Steven Lacey.) (Los Angeles Times)

A Lancaster Mk III (PA474), of the type involved in a number of UFO encounters during the Second World War. (Timothy Good)

A Thunderbolt P-47D similar to the type flown by Free French Air Force pilot Jean Kisling, when he attempted to shoot down a UFO above Mount Clemens Army Air Base near Detroit in July 1945. (Republic Aviation)

Jean Kisling at Oscoda (later Wurtsmith AFB), a sub-base for Mount Clemens, in 1944. (Jean Kisling)

In August 1945, a C-46 Commando was en route to Tokyo via Iwo Jima when three unknown objects closed with the plane, causing the port engine to stall and the plane to lose altitude. (US Air Force)

Artwork depicting a Saab B18 of the Royal Swedish Air Force and one of the ‘ghost rockets’ it encountered on the morning of 14 August 1946. (© Johan Andersson)

The first American-adapted V-2 at White Sands, New Mexico, shown during engine check-out. (US Army)

A contemporary news report of the UFO interference encountered during the tests in May 1947. (Las Cruces Sun News)

Dr Wernher von Braun, designer of the V-2 rocket and advisor to the US Army V-2 test firings at White Sands. He also examined the craft and alien bodies discovered near Roswell.

Lieutenant Colonel Philip Corso (left), who stewarded the Roswell artefacts in a reverse-engineering project instigated by Lieutenant General Arthur Trudeau (right). (Collection of Philip Corso Jr.)

Congressman Steven Schiff, whose request to see official records pertaining to the Roswell incident revealed that they had been destroyed without proper authority. (Timothy Good)

Jon ‘Andy’ Kissner. His pioneering research reveals that attacks on the UFOs by the US military in the 1940s led to a worldwide wave of crashes of military and civilian aircraft. (Timothy Good)

Roswell Army Air Field, home of the 509th Bombardment Group, the world’s first unit equipped to carry nuclear weapons, where one or two alien craft plus bodies were first taken after crashes in New Mexico in July 1947. (Timothy Good)

A B-25 Mitchell bomber, of the type used to fly some or all of the debris found by Mac Brazel to Fort Worth, Texas. (Timothy Good)

Major General Clements McMullen, who ordered the containment strategy to cover up the Roswell incident. US Air Force)

1st Lieutenant Eileen M. Fanton, the nurse said to have attended the autopsy of one of the alien beings at Roswell Army Air Field. (US Air Force)

Artwork by Glenn Dennis based on drawings by the nurse who attended one of the alien autopsies. The fingertips appeared to have suction cups and the eyes were sunken so far back – from exposure to the desert – that it was difficult to tell what they looked like. (Glenn Dennis)

P-51 Mustangs of the California Air National Guard, of the type Captain Thomas Mantell was flying when he was killed intercepting a UFO in January 1948. An intelligence report (below) confirms that his last radio message was, ‘It appears to be metallic object … of tremendous size … directly ahead and slightly above … I am trying to close for a better look.’ (Via Philip Jarrett)

Part of a US Air Force Intelligence summary referencing the incident, confirming Mantell’s last radio message to Godman AFB control tower. (US Air Force)

Captain Thomas F. Mantell, who was killed while intercepting a UFO near Franklin, Kentucky, on 7 January 1948. (US Air Force)

Frederick C. Durant III, a Naval aviator, test pilot and instructor, who later became an expert on missiles, rockets and UFOs. He is shown here as an ensign, serving with Squadron VN15 in 1942. (US Navy)

General Hoyt Vandenberg, second Director of Central Intelligence. When a Top Secret report concluded that UFOs were interplanetary, he ordered it to be burned. ( US Air Force)

Wilbert B. Smith, who headed the Canadian Government’s first Top Secret investigations into UFOs. (Van’s Studio, Ottawa)

Royal Air Force Flight-Lieutenant Stan Hubbard, who observed a disc of about 100 feet in diameter over the experimental aircraft test centre at Farnborough, Hampshire, in August 1950. (Stan Hubbard / UFO Magazine – UK)

One of four photographs taken through a telescope by George Adamski in California, 5 March 1951, showing a ‘mothership’ releasing smaller ‘scout’ craft. (George Adamski Foundation)

UFO photographed by a US Marine Air Group pilot over the northeast China Sea during the Korean War. The object came close to the aircraft before shooting off at over 1,000 mph. It had a very bright top, which “burned” into the film emulsion, and a bronze coloured base. (W. Gordon Allen)

Leroy Gordon Cooper, the pilot, pioneer astronaut and UFO researcher, to whom this book is dedicated. While stationed in Germany in 1951, Cooper was scrambled on several occasions to intercept flying discs. (Flight Data Center)

Captain Edward J. Ruppelt, the intelligence officer who was the first head of the US Air Force”s Project Blue Book.

Major Donald E. Keyhoe, former US Marine Corps pilot and first exposer of the UFO cover-up. (Fortean Picture Library)

The Washington Post lead story for 29 July 1952. Pilots and radar navigators outside their F-94B Starfire interceptors at Newcastle AFB, Delaware, at the time of the UFO air alerts above Washington, DC, July 1952. (UPI Newspictures)

An F9F Panther jet of the type flown by Marine 1st Lieutenant Eddy P. Balocco when he was scrambled to intercept a UFO in February 1953 near Edenton, North Carolina. (US Navy via Philip Jarrett)

Two F-102 Delta Dagger jets, like those scrambled to intercept a stationary object in the sky over California in 1961. The crew calculated its sudden departure at nearly 36,000 mph. (US Air Force via Robert F. Dorr)

In June 1953, a Lockheed F-94C Starfire like this one was scrambled to intercept an unknown target at Otis AFB, Massachusetts. Shortly after take-off the power failed. The pilot ejected safely, without the radar operator, who, along with the aircraft, was never found. (The National Archives, Washington, DC)

The mighty Convair B-36 Peacemaker, capable of carrying nuclear weapons, had several encounters with UFOs. One such was in late 1956 over the North/South Dakota border, when all seventeen crew members plus a five-man relief crew saw a 100ft craft with a dome and what appeared to be portholes or lights. (Don Bishop)

A radarscope photograph of UFOs off Bermuda, taken from a US Air Force plane on 3 July 1954. (The National Archives, Washington, DC)

This UFO was photographed in 1963 by the co-pilot of an AVENSA Airlines DC-4 between Barcelona and Maiquetia in Venezuela. A propeller spinner can be seen in the right foreground, and a highway divides the trees. Fernando de Calvet, a professional topographer and geometrician, demonstrated mathematically that all of the objects in the photograph bear exact relation with each other. (Aerial Phenomena Research Organisation)

President John F. Kennedy was allegedly taken on this Air Force One (Boeing VC-137C) to view deceased alien bodies at a US Air Force base in Florida. (US Air Force)

An Atlas-F intercontinental ballistic missile. In September 1964, an Atlas with a dummy nuclear warhead, test-fired from Vandenberg AFB, California, was approached by a classic disc-shaped craft which fired flashes of light at it. The warhead malfunctioned and tumbled out of sub-orbit. The event – confirmed by several military personnel – was recorded on 35mm movie film through a high-powered telescope. (US Air Force)

A frame from the 8mm colour movie film taken by George Adamski in the presence of Madeleine Rodeffer and other witnesses at Silver Spring, Maryland (near Washington, DC) in February 1965. During a meeting with the author at the Pentagon in May 1998, the Director of the Defense Airborne Reconnaissance Office stated his opinion that this and other frames from the film seemed genuine. (Madeleine Rodeffer)

Sketch of the object which crashlanded near the village of Kecksburg, Pennsylvania, in December 1965. (C. M. Hanna)

Left. The USS John F. Kennedy (CV-67). In June/July 1971 a massive, glowing, spherical UFO appeared over the carrier, disrupting communications and electrical systems. (US Navy) Right. James M. Kopf, one of the witnesses, a communications specialist holding Top Secret Crypto clearance at the time.

The USS Leary DD-879, which had an encounter with an unidentified submarine object during the Vietnam War. (US Navy)

The Dassault Mirage IVA, France’s supersonic bomber capable of carrying a 60-kiloton nuclear weapon. In March 1977, Colonel René Giraud and his navigator encountered a huge UFO, ‘at least as big as a Boeing 747’, while flying a Mirage IVA over Chaumont. (Via Philip Jarrett)

The British Vulcan bomber, designed to carry nuclear weapons. In May 1977, the crew of this Vulcan reported a UFO over the Bay of Biscay. The aircraft – Vulcan B.2 Blue Steel XL321 of 617 Squadron – is shown here at RAF Finningley in 1969. (Steve Williams)

A photograph taken in September 1985 of the object which had nearly collided head-on with a Cessna 337 Super Skymaster over the Mojave Desert. (David J. Hastings)

Yuri Andropov, former Soviet president and head of the KGB. In 1977/78 he instigated a top- secret ten-year UFO research programme involving four million military officers. (US Information Service)

A Japan Airlines Boeing 747–400 cargo jet, and a drawing of the object seen from one of these aircraft over Alaska in November 1986, sketched by Captain Kenju Terauchi. The jumbo jet, shown on the right, was dwarfed by the craft. (Japan Airlines / Kenju Terauchi)

In July 1976, two Indian Air Force MiG-21s, such as the one shown here, witnessed a discshaped object on the Pakistan border, which flew away at an estimated 2,600 mph when approached. (Indian Air Force)

An F-4 Phantom jet, frequently involved in UFO interceptions, such as those in Germany and Iran in 1976. (Timothy Good)

A Chinese Shenyang JJ-6, like the one scrambled to intercept a UFO near Changzhou City in October 1998. The UFO repeatedly played ‘cat and mouse’ with the jet. Permission to fire at the object was denied. (Chinese Air Force)

On 4 January 2004, this Boeing 737–448 of Aer Lingus was allegedly harrassed by a riangularshaped craft prior to landing at Dublin Airport. The airliner experienced a power drain, there was a great deal of turbulence, the outside air temperature rose to 164° Centigrade and the plane suffered damage to the wings and air brakes. (Andrzej Krzewski)

John Podesta, formerly President Clinton’s Chief of Staff. ‘It’s time to open the books … on the question of government investigations of UFO’s,’ he said in 2002. ‘We ought to do it because the American people, quite frankly, can handle the truth; and we ought to do it because it’s the law.’ (Leslie Kean)

‘UFOs are as real as the airplanes that fly over your head,’ said retired Canadian Minister of Defence Paul Hellyer (right) in 2005. ‘The secrecy involved in all matters pertaining to the Roswell incident was unparalleled … so the vast majority of US officials [and] politicians … were never in the loop.’ (Ethan Eisenberg)