On May 1:
305 Diocletian and Maximian retired from the office of Roman Emperor.
880 The Nea Ekklesia was inaugurated in Constantinople setting the model for all later cross-in-square Orthodox churches.
1328 Wars of Scottish Independence ended: Treaty of Edinburgh-Northampton – the Kingdom of England recognised the Kingdom of Scotland as an independent state.
1576 Stefan Batory, the reigning Prince of Transylvania, married Anna Jagiellon and they became the co-rulers of the Polish-Lithuanian Commonwealth.
1707 The Act of Union joined the Kingdom of England and Kingdom of Scotland to form the Kingdom of Great Britain.
1751 The first cricket match was played in America.
1753 Publication of Species Plantarum by Linnaeus, and the formal start date of plant taxonomy adopted by the International Code of Botanical Nomenclature.
1759 Josiah Wedgwood founded the Wedgwood pottery company in Great Britain.
1776 Establishment of the Illuminati in Ingolstadt (Upper Bavaria), by Jesuit-taught Adam Weishaupt.
1778 American Revolution: The Battle of Crooked Billet began in Hatboro, Pennsylvania.
1785 Kamehameha, the king of Hawaiʻi defeated Kalanikupule and established the Kingdom of Hawaiʻi.
1786 Opening night of the opera The Marriage of Figaro by Wolfgang Amadeus Mozart in Vienna.
1831 Emily Stowe, Canadian physician and suffragist, was born (d. 1903).
1834 The British colonies abolished slavery.
1840 The Penny Black, the first official adhesive postage stamp, was issued in the United Kingdom.
1846 The few remaining Mormons left in Nauvoo, Illinois, formally dedicated the Nauvoo Temple.
1848 The Fraternity of Phi Gamma Delta was founded at Jefferson College in Canonsburg, Pennsylvania.
1851 Queen Victoria opened the Great Exhibition in London.
1852 Calamity Jane, American Wild West performer, was born (d. 1903).
1852 The Philippine peso was introduced into circulation.
1863 American Civil War: The Battle of Chancellorsville began.
1865 The Empire of Brazil, Argentina and Uruguay signed the Treaty of the Triple Alliance.
1869 The Folies Bergère opened in Paris.
1875 Alexandra Palace reopened after the 1873 fire burnt it down.
1884 Proclamation of the demand for eight-hour workday in the United States.
1884 Moses Fleetwood Walker became the first black person to play in a professional baseball game in the United States.
1885 Ralph Stackpole, American sculptor, painter, was born (d. 1973).
1886 Rallies, that ended in the Haymarket affair, were held throughout the United States demanding the eight-hour work day.
1893 The World’s Columbian Exposition opened in Chicago.
1893 Richard Seddon became Premier of New Zealand.
1894 Coxey’s Army, the first significant American protest march, arrived in Washington, D.C.
1898 Spanish-American War: The Battle of Manila Bay – the United States Navy destroyed the Spanish Pacific fleet in the first battle of the war.
1900 The Scofield mine disaster killed more than 200 men in Scofield, Utah.
1901 The Pan-American Exposition opened in Buffalo, New York.
1910 Dr. J. Allen Hynek, Astronomer/Astro-physicist. Noted UFO investigator, was born (d. 1986).
1915 The RMS Lusitania departed from New York City on her two hundred and second, and final, crossing of the North Atlantic.
1925 The All-China Federation of Trade Unions was officially founded.
1926 New Zealand Railways magazine was launched.
1927 The first cooked meals on a scheduled flight were introduced on an Imperial Airways flight from London to Paris.
1927 The Union Labor Life Insurance Company was founded by the American Federation of Labor.
1930 The dwarf planet Pluto was officially named.
1931 The Empire State Building was dedicated in New York City.
1937 Una Stubbs, English actress, was born.
1939 Judy Collins, American folk singer, was born.
1940 The 1940 Summer Olympics were cancelled owing to war.
1941 – World War II: German forces launch a major attack on Tobruk.
1945 World War II: A German newsreader officially announced that Adolf Hitler had “fallen at his command post in the Reich Chancellery fighting to the last breath against Bolshevism and for Germany”.
1945 Yougoslav partisans freed Trieste.
1945 Rita Coolidge, American singer, was born.
1946 Joanna Lumley, English actress, was born.
1946 Start of 3 year Pilbara strike of Indigenous Australians.
1946 The Paris Peace Conference concluded that the islands of the Dodecanese should be returned to Greece by Italy.
1947 Portella della Ginestra massacre against May Day celebrations in Sicily by the bandit and separatist leader Salvatore Giuliano; 11 people were killed and 33 wounded.
1948 The Democratic People’s Republic of Korea (North Korea) was established, with Kim Il-sung as president.
1950 Guam was organized as a United States commonwealth.
1956 The polio vaccine developed by Jonas Salk was made available to the public.
1956 A doctor in Japan reported an “epidemic of an unknown disease of the central nervous system”, marking the official discovery of Minamata disease.
1960 Formation of the western Indian states of Gujarat and Maharashtra.
1960 Cold War: U-2 incident – Francis Gary Powers, in a Lockheed U-2 spyplane, iwa shot down over the Soviet Union, sparking a diplomatic crisis.
1961 The Prime Minister of Cuba, Fidel Castro, proclaimed Cuba a socialist nation and abolishes elections.
1965 Battle of Dong-Yin, a naval conflict between ROC and PRC, took place.
1970 Protests erupted in Seattle, Washington, following the announcement by U.S. President Richard Nixon that U.S. Forces in Vietnam would pursue enemy troops into Cambodia, a neutral country.
1971 Amtrak (the National Railroad Passenger Corporation) was formed to take over U.S. passenger rail service.
1977 36 people were killed in Taksim Square, Istanbul, during the Labour Day celebrations.
1978 Japan’s Naomi Uemura, travelling by dog sled, became the first person to reach the North Pole alone.
1982 The 1982 World’s Fair opened in Knoxville, Tennessee.
1982 Operation Black Buck: The Royal Air Force attacked the Argentine Air Force during Falklands War.
1983 Greek composer Mikis Theodorakis was awarded the Lenin Peace Prize.
1987 Pope John Paul II beatified Edith Stein, a Jewish-born Carmelite nun who was gassed in the Nazi concentration camp at Auschwitz.
1989 Disney-MGM Studios opened at Walt Disney World near Orlando, Florida.
1990 The former Philippine Episcopal Church (supervised by the Episcopal Church of the United States of America) was granted full autonomy and raised to the states of an Autocephalous Anglican Province and renamed the Episcopal Church of the Philippines.
1992 On the third day of the 1992 Los Angeles riots, African-American activist, criminal, and victim of police beating Rodney King appeared in public before television news cameras to appeal for calm and plead for peace, asking, “People, I just want to say, you know, can we all get along?”.
1994 Three-time Formula One world champion Ayrton Senna was killed in an accident during the San Marino Grand Prix at Imola.
1995 Croatian forces launch Operation Flash during the Croatian War of Independence.
1997 Tasmania became the last state in Australia to decriminalize homosexuality.
2001 Philippine President Gloria Macapagal-Arroyo declared the existence of “a state of rebellion”, hours after thousands of supporters of her arrested predecessor, Joseph Estrada, stormed towards the presidential palace at the height of the EDSA III rebellion.
2003 2003 invasion of Iraq: In the “Mission Accomplished” speech, on board the USS Abraham Lincoln (off the coast of California), U.S. President George W. Bush declaref that “major combat operations in Iraq have ended”.
2004 Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia joined the European Union, celebrated at the residence of the Irish President in Dublin.
2006 The Puerto Rican government closed the Department of Education and 42 other government agencies owing to to significant shortages in cash flow.
2007 the Los Angeles May Day mêlée occured, in which the Los Angeles Police Department’s response to a May Day pro-immigration rally become a matter of controversy.
2008 The London Agreement on translation of European patents, concluded in 2000, entered into force in 14 of the 34 Contracting States to the European Patent Convention.
2009 Same-sex marriage was legalised in Sweden.
2010 – attempted car bombing of Times Square.
Sourced from NZ History Online & Wikipedia