April 1973

• VAT comes into effect in the UK.[1]
• The U.S. Army Health Services Command is activated as part of a reorganization of the Army Medical Department, and takes control of Army medical facilities in the continental US.[2]
• The Government of India launches a campaign to save the tiger from extinction.
• British European Airways begins replacing Viscounts and Tridents on the Aberdeen–Heathrow route with One-Eleven 500s, as the latter are considered more efficient and have greater passenger appeal.[3][4]
• The first Doraemon anime begins airing on Nippon TV in Japan.
• Project Tiger was launched in India

• The Civil Authorities (Special Powers) Act (Northern Ireland) 1922 is replaced by the Northern Ireland (Emergency Provisions) Act[5] abolishing the death penalty for murder in Northern Ireland and establishing the Diplock courts.
• The Radio Veronica pirate radio ship is driven ashore at Scheveningen in a storm after her anchor chain snaps.[6]
• The LexisNexis computerized legal research service begins.

• The first handheld cellular phone call is made by Martin Cooper in New York City.
• Montreal announces Canada's first lottery to help pay for the 1976 Summer Olympics
• Born: Adam Scott, American actor

• The World Trade Center officially opens in New York City with a ribbon cutting ceremony.
• Pierre Werner extends the operating concession to Compagnie Luxembourgeoise de Télédiffusion, now RTL Group, until 31 December 1995.[7]
• Born: David Blaine, American illusionist and endurance artist, in Brooklyn, New York.

The launch of the Atlas-Centaur carrying the Pioneer G (11) spacecraft on April 5, 1973.

• Pioneer 11 is launched on a mission to study the solar system.
• Born: Pharrell Williams, American singer-songwriter, in Virginia Beach, Virginia.

• Fahri Korutürk becomes the sixth President of Turkey.[8]
• Pierre Messmer appoints his second cabinet as Prime Minister of France.
• Launch of the Pioneer 11 spacecraft.
• Ron Blomberg of the New York Yankees becomes the first designated hitter in Major League Baseball.

• Tu te reconnaîtras by Anne-Marie David (music by Claude Morgan, text by Vline Buggy) wins the Eurovision Song Contest 1973 for Luxembourg.
• The 1973 International Seven-A-Side Tournament, the first Rugby Sevens tournament to feature national representative teams,[9] is won by England.

• Jackie Stewart wins the 1973 BRDC International Trophy motor race at Silverstone.
• Born: Flying Water, French Thoroughbred racehorse (died 1978)
• Died: Pablo Picasso, 91, Spanish artist

• Israel launches Operation Spring of Youth, an attack on several Palestine Liberation Organization (PLO) targets in Beirut and Sidon, Lebanon,[10] in revenge for the Munich massacre at the Summer Olympics in the previous year.[11]
• United Nations-Organization for African Unity conference on Southern Africa opens in Oslo.[12]

• The Israeli Knesset elects Ephraim Katzir as President of Israel, by a majority of 66 votes to 41 votes cast in favour of his opponent, Ephraim Urbach.
• Israeli commandos raid Beirut, assassinating 3 leaders of the Palestinian Resistance Movement. The Lebanese army's inaction brings the immediate resignation of Prime Minister Saib Salam, a Sunni Muslim.
• A new Constitution of Pakistan is approved by the legislative assembly.[8][13]
• Invicta International Airlines Flight 435, a chartered Vickers Vanguard 952, carrying mostly members of the Axbridge Ladies Guild from Somerset, UK, crashes into a snowy, forested hillside near Hochwald, Switzerland; 108 of the 145 people on board are killed and all but one of the 37 survivors injured. The crash leaves 55 children motherless.
• Born:Selahattin Demirtaş, Turkish-Kurdish politician, in Elaziğ

• The British House of Commons votes against restoring capital punishment by a margin of 142 votes.

• The Labour Party wins control of the Greater London Council.

• Acting US Assistant Secretary of Defense for Public Affairs, Jerry W. Friedheim, is confirmed in his position.
• Died: Balraj Sahni, 59, Punjabi film actor

• Born: Adrien Brody, American actor, in Woodhaven, Queens, New York

• Naim Talu, a former civil servant, forms the new government of Turkey (36th government)

• Controversial US sheriff Noah W. Cross, having pleaded guilty to a charge of jury tampering, is ordered to report to U.S. marshals in Shreveport for transportation to federal prison.[14]
• Died: Istvan Kertesz, Hungarian conductor, 43 (drowned); Nino Bravo, 28, Spanish singer (car accident)

• The German counter-terrorist force GSG 9 is officially formed.
• Federal Express officially begins operations, with the launch of 14 small aircraft from Memphis International Airport. On that night, Federal Express delivers 186 packages to 25 U.S. cities from Rochester, New York, to Miami, Florida.
• The Morganza Spillway on the Mississippi River is opened for the first time to prevent catastrophic flooding of New Orleans.
• British Leyland launches its new Austin Allegro range of small family saloons, to replace the ageing 1100 and 1300 ranges that were sold under the Austin, Morris, Riley, Wolseley, MG and Vanden Plas brands from the range's 1962 launch.
• George Lucas begins writing the treatment for The Star Wars.

• The 93rd Parliament of Iceland concludes.
• Born: Haile Gebrselassie, Ethiopian athlete, in Asella

• The Portuguese Socialist Party, Partido Socialista, is founded in the German city of Bad Münstereifel, by militants from Portuguese Socialist Action (Portuguese: Acção Socialista Portuguesa).
• Sosnovy Bor, Leningrad Oblast, is granted town status by the Soviet government.
• Mississippi Flood of 1973: The Morganza Spillway is opened, flooding portions of the Atchafalaya River basin in Louisiana and causing the deaths of thousands of head of livestock and white-tailed deer.[15]
• Died: Hans Kelsen, 91, Austrian legal theorist

• An Indian Pacific train en route to Perth, derails near Broken Hill, New South Wales, destroying a quarter mile of track.

• Pakistan Broadcasting Corporation establishes the Pakistan World Service for overseas Pakistanis.
• Died: Merian C. Cooper, 79, American aviator, director, and producer; Arthur Fadden, 79, 13th Prime Minister of Australia

• The final Singapore Grand Prix is held before the event is discontinued. (It was brought back in 2008 as a round of the Formula One World Championship.) The race is won by Vern Schuppan of Australia.

• The 1973 Swedish Pro Tennis Championships open in Gothenburg.
• Born: Zubin Damania, American physician and Internet personality, in New Jersey

• The US Aggressive-class minesweeper Force suffers an engine room fire, and sinks off Guam.
• Born: Sachin Tendulkar, Indian cricketer and politician, in Mumbai
• The judgement on Kesavananda Bharati v. State of Kerala case by Supreme Court of India

US performs a nuclear test at the Nevada Test Site

• The first day of trading on the Chicago Board Options Exchange.
• Died: Irene Ryan, 70, US actress

• The Singapore cargo ship Globe Star runs aground on the Nyali Reef, off Mombasa, Kenya. Five people are killed during salvage operations in November 1973, and the ship is later scrapped in situ.
• The German coaster Belle Virtue collides with Panama's Maritime Pioneer in the English Channel and sank. All eight crew were rescued by Suderau ( West Germany).[16]

• The last section of the IRT 3rd Avenue Elevated Line from 149th Street in the Bronx in New York City, to Gun Hill Road, also in the Bronx, is closed.
• Six Irishmen, including Joe Cahill, are arrested by the Irish Naval Service off County Waterford, on board a coaster carrying 5 tons of weapons destined for the Provisional Irish Republican Army.
• Liverpool and Celtic are league champions of England and Scotland respectively.[17]
• Died: Jacques Maritain, 90, Catholic philosopher; Nikos Zachariadis, 70, Greek Communist politician (alleged suicide while a prisoner in the Soviet Union)

• Sardar Inayatullah Khan Gandapur becomes Chief Minister of Khyber Pakhtunkhwa.
• The singles competition at the 1973 Swedish Pro Tennis Championships in Gothenburg is won by Stan Smith. The doubles are won by Roy Emerson and Rod Laver.
• The Chesapeake passenger train service is established between Washington, D.C. and New York City, US.

• Watergate Scandal: President Richard Nixon announces that top White House aides H.R. Haldeman, John Ehrlichman, and others have resigned.[8]
• Born: Leigh Francis, British comedian and actor, in Beeston, Leeds
• Died: Václav Renč, Czech poet, 61, dramatist and translator