Bulgaria: Bulgarian Education and Culture, and Slavonic Literature Day
1218 - The Fifth Crusade leaves Acre for Egypt.
1276 - Magnus Ladulås is crowned King of Sweden in Uppsala Cathedral.
1487 - Lambert Simnel is crowned as "King Edward VI" at Dublin, Ireland.
1595 - Nomenclator of Leiden University Library appears, the first printed catalog of an institutional library.
1621 - The Protestant Union is formally dissolved.
1626 - Peter Minuit buys Manhattan.
1689 - The English Parliament passes the Act of Toleration protecting Protestants. Roman Catholics are intentionally excluded.
1738 - John Wesley is converted, essentially launching the Methodist movement; the day is celebrated annually by Methodists as Aldersgate Day.
1798 - Irish Rebellion of 1798 led by the United Irishmen against British rule begins.
1822 - Battle of Pichincha: Antonio José de Sucre secures the independence of the Presidency of Quito.
1830 - "Mary Had a Little Lamb" by Sarah Josepha Hale is published.
1830 - The first revenue trains in the United States begin service on the Baltimore and Ohio Railroad between Baltimore, Maryland and Ellicott's Mills, Maryland.
1832 - The First Kingdom of Greece is declared in the London Conference.
1844 - Samuel F. B. Morse sends the message "What hath God wrought" (a Bible quotation, Numbers 23:23) from the Old Supreme Court Chamber in the United States Capitol to his assistant, Alfred Vail, in Baltimore, Maryland.
1846 - Mexican-American War: General Zachary Taylor captures Monterrey.
1856 - John Brown and his men murder five slavery supporters at Pottawatomie Creek, Kansas.
1861 - American Civil War: Union troops occupy Alexandria, Virginia.
1881 - Turkey cedes Thessaly and Arta back to Greece.
1883 - The Brooklyn Bridge in New York City is opened to traffic after 14 years of construction.
1895 - Henry Irving becomes the first personage from the theatre to be knighted.
1900 - Second Boer War: The United Kingdom annexes the Orange Free State.
1901 - Seventy-eight miners die in the Caerphilly pit disaster in South Wales.
1915 - World War I: Italy declares war on Austria-Hungary.
1921 - The trial of Sacco and Vanzetti opens.
1930 - Amy Johnson lands in Darwin, Northern Territory, becoming the first woman to fly from England to Australia (she left on May 5 for the 11,000 mile flight).
1935 - The first night game in Major League Baseball history is played in Cincinnati, Ohio, with the Cincinnati Reds beating the Philadelphia Phillies 2-1 at Crosley Field.
1940 - Igor Sikorsky performs the first successful single-rotor helicopter flight.
1941 - World War II: In the Battle of the Atlantic, the German Battleship Bismarck sinks the then pride of the Royal Navy, HMS Hood, killing all but three crewmen.
1943 - Holocaust: Josef Mengele becomes chief medical officer of the Auschwitz concentration camp.
1956 - Conclusion of the Sixth Buddhist Council on Vesak Day, marking the 2,500 year anniversary after the Lord Buddha's Parinibbāna.
1956 - The first Eurovision Song Contest is held in Lugano, Switzerland
1958 - United Press International is formed through a merger of the United Press and the International News Service.
1961 - American civil rights movement: Freedom Riders are arrested in Jackson, Mississippi for "disturbing the peace" after disembarking from their bus.
1961 - Cyprus enters the Council of Europe.
1962 - Project Mercury: American astronaut Scott Carpenter orbits the Earth three times in the Aurora 7 space capsule.
1968 - FLQ separatists bomb the U.S. consulate in Quebec City.
1970 - The drilling of the Kola Superdeep Borehole begins in the Soviet Union.
1973 - Earl Jellicoe resigns as Lord Privy Seal and Leader of the Lords.
1976 - The London to Washington, D.C. Concorde service begins.
1976 - In the Judgment of Paris, wine testers rate wines from California higher than their French counterparts, challenging the notion of France being the foremost producer of the world's best wines.
1980 - The International Court of Justice calls for the release of United States embassy hostages in Tehran, Iran. The hostages would not be freed until the following January.
1982 - Liberation of Khorramshahr, Iranians recapture of the port city of Khorramshahr from the Iraqis during the Iran–Iraq War.
1988 - Section 28 is passed as law by Parliament in the United Kingdom.
1989 - Sonia Sutcliffe, wife of the Yorkshire Ripper, is awarded £600,000 in damages (later reduced to £60,000 on appeal) after winning a libel action against Private Eye.
1990 - A car carrying American Earth First! activists Judi Bari and Darryl Cherney explodes in Oakland, California, critically injuring both.
1991 - Eritrea gains its independence from Ethiopia.
1991 - Israel conducts Operation Solomon, evacuating Ethiopian Jews to Israel.
1992 - The last Thai dictator, General Suchinda Kraprayoon, resigns following pro-democracy protests.
1994 - Four men convicted of bombing the World Trade Center in New York in 1993 are each sentenced to 240 years in prison.
1999 - Venezuela enters the Antarctic Treaty System.
2000 - Israeli troops withdraw from southern Lebanon after 22 years of occupation.
2001 - Mountain climbing: 15-year-old Sherpa Temba Tsheri becomes the youngest person to climb to the top of Mount Everest.
2001 - The Versailles wedding hall disaster in Jerusalem, Israel, kills 23 and injures over 200 in Israel's worst-ever civil disaster.
2002 - Russia and the United States sign the Moscow Treaty.
2004 - Communications in North Korea: North Korea bans mobile phones.