311 – The Diocletianic Persecution of Christians in the Roman Empire ends.
313 – Battle of Tzirallum: Emperor Licinius defeats Maximinus II and unifies the Eastern Roman Empire.
642 – Chindasuinth is proclaimed king by the Visigothic nobility and bishops.
1315 – Enguerrand de Marigny is hanged on the public gallows at Montfaucon.
1492 – Spain gives Christopher Columbus his commission of exploration.
1513 – Edmund de la Pole, Yorkist pretender to the English throne, is executed on the orders of Henry VIII.
1517 – Evil May Day xenophobic riots in London begin
1557 – Mapuche leader Lautaro is killed by Spanish forces at the Battle of Mataquito in Chile.
1598 – Juan de Oñate makes a formal declaration of his Conquest of New Mexico. Henry IV of France issues the Edict of Nantes, allowing freedom of religion to the Huguenots.
1636 – Eighty Years' War: Dutch Republic forces recapture a strategically important fort from Spain after a nine-month siege.
1671 – Petar Zrinski, the Croatian Ban from the Zrinski family, is executed.
1789 – On the balcony of Federal Hall on Wall Street in New York City, George Washington takes the oath of office to become the first elected President of the United States.
1803 – Louisiana Purchase: The United States purchases the Louisiana Territory from France for $15 million, more than doubling the size of the young nation.
1812 – The Territory of Orleans becomes the 18th U.S. state under the name Louisiana.
1838 – Nicaragua declares independence from the Central American Federation.
1863 – A 65-man French Foreign Legion infantry patrol fights a force of nearly 2,000 Mexican soldiers to nearly the last man in Hacienda Camarón, Mexico.
1871 – The Camp Grant massacre takes place in Arizona Territory.
1885 – Governor of New York David B. Hill signs legislation creating the Niagara Reservation, New York's first state park, ensuring that Niagara Falls will not be devoted solely to industrial and commercial use.
1897 – J. J. Thomson of the Cavendish Laboratory announces his discovery of the electron as a subatomic particle, over 1,800 times smaller than a proton (in the atomic nucleus), at a lecture at the Royal Institution in London.
1900 – Hawaii becomes a territory of the United States, with Sanford B. Dole as governor.
1904 – The Louisiana Purchase Exposition World's Fair opens in St. Louis, Missouri.
1907 – Honolulu, Hawaii becomes an independent city.
1925 – Automaker Dodge Brothers, Inc is sold to Dillon, Read & Co. for US$146 million plus $50 million for charity.
1927 – The Federal Industrial Institute for Women opens in Alderson, West Virginia, as the first women's federal prison in the United States.
1927 – Douglas Fairbanks and Mary Pickford become the first celebrities to leave their footprints in concrete at Grauman's Chinese Theater in Hollywood.
1937 – The Commonwealth of the Philippines holds a plebiscite for Filipino women on whether they should be extended the right to suffrage; over 90% would vote in the affirmative.
1938 – The animated cartoon short Porky's Hare Hunt debuts in movie theaters, introducing Happy Rabbit (a prototype of Bugs Bunny).
1939 – The 1939-40 New York World's Fair opens.
1939 – NBC inaugurates its regularly scheduled television service in New York City, broadcasting President Franklin D. Roosevelt's N.Y. World's Fair opening day ceremonial address.
1943 – World War II: Operation Mincemeat: The submarine HMS Seraph surfaces in the Mediterranean Sea off the coast of Spain to deposit a dead man planted with false invasion plans and dressed as a British military intelligence officer.
1945 – World War II: Führerbunker: Adolf Hitler and Eva Braun commit suicide after being married for less than 40 hours. Soviet soldiers raise the Victory Banner over the Reichstag building.
1947 – In Nevada, Boulder Dam is renamed Hoover Dam for the second time.
1948 – In Bogotá, Colombia, the Organization of American States is established.
1956 – Former Vice President and Democratic Senator Alben Barkley dies during a speech in Virginia. He collapses after proclaiming "I'm glad to sit on the back row, for I would rather be a servant in the house of the lord than sit in the seats of the mighty."
1957 – Supplementary Convention on the Abolition of Slavery entered into force.
1961 – K-19, the first Soviet nuclear submarine equipped with nuclear missiles, is commissioned.
1963 – The Bristol Bus Boycott is held in Bristol to protest the Bristol Omnibus Company's refusal to employ Black or Asian bus crews, drawing national attention to racial discrimination in the United Kingdom.
1973 – Watergate scandal: U.S. President Richard Nixon announces that White House Counsel John Dean has been fired and that other top aides, most notably H. R. Haldeman and John Ehrlichman, have resigned.
1975 – Fall of Saigon: Communist forces gain control of Saigon. The Vietnam War formally ends with the unconditional surrender of South Vietnamese president Dương Văn Minh.
1980 – The Iranian Embassy siege begins in London.
1982 – The Bijon Setu massacre occurs in Calcutta.
1993 – CERN announces World Wide Web protocols will be free.
1994 – Formula One racing driver Roland Ratzenberger is killed in a crash during the qualifying session of the San Marino Grand Prix run at Autodromo Enzo e Dino Ferrari outside Imola, Italy.
1998 – United Nations Security Council Resolution 1165 relating to Rwanda Tribunal is adopted.
2000 – Canonization of Faustina Kowalska in the presence of 200,000 people and the first Divine Mercy Sunday celebrated worldwide.
2004 – U.S. media release graphic photos of American soldiers abusing and sexually humiliating Iraqi prisoners at Abu Ghraib prison.
2008 – Two skeletal remains found near Yekaterinburg, Russia are confirmed by Russian scientists to be the remains of Alexei and Anastasia, two of the children of the last Tsar of Russia, whose entire family was executed at Yekaterinburg by the Bolsheviks.
2009 – Chrysler files for Chapter 11 bankruptcy.
2009 – Seven people are killed and another ten injured at a Queen's Day parade in Apeldoorn, Netherlands in an attempted assassination on Queen Beatrix.
2012 – An overloaded ferry capsizes on the Brahmaputra River in India killing at least 103 people.
2013 – Queen Beatrix of the Netherlands abdicates and Willem-Alexander becomes King of the Netherlands.
2014 – A bomb blast in Ürümqi kills three people and injures 79 others.