585 - A solar eclipse occurs, as predicted by Greek philosopher and scientist Thales, while Alyattes is battling Cyaxares in the Battle of the Eclipse, leading to a truce. This is one of the cardinal dates from which other dates can be calculated.
1503 - James IV of Scotland and Margaret Tudor are married according to a Papal Bull by Pope Alexander VI. A Treaty of Everlasting Peace between Scotland and England signed on that occasion results in a peace that lasts ten years.
1533 - The Archbishop of Canterbury Thomas Cranmer declares the marriage of King Henry VIII of England to Anne Boleyn valid.
1588 - The Spanish Armada, with 130 ships and 30,000 men, sets sail from Lisbon heading for the English Channel. (It will take until May 30 for all ships to leave port).
1644 - Bolton Massacre by Royalist troops under the command of the Earl of Derby.
1754 - French and Indian War: in the first engagement of the war, Virginia militia under 22-year-old Lieutenant Colonel George Washington defeat a French reconnaissance party in the Battle of Jumonville Glen in what is now Fayette County in southwestern Pennsylvania.
1774 - American Revolutionary War: the first Continental Congress convenes.
1830 - President Andrew Jackson signs The Indian Removal Act which relocates Native Americans.
1863 - American Civil War: the 54th Massachusetts Volunteer Infantry, the first African American regiment, leaves Boston, Massachusetts, to fight for the Union.
1892 - In San Francisco, California, John Muir organizes the Sierra Club.
1905 - Russo-Japanese War: the Battle of Tsushima ends with the destruction of the Russian Baltic Fleet by Admiral Togo Heihachiro and the Imperial Japanese Navy.
1918 - The Democratic Republic of Armenia declares its independence.
1918 - The Azerbaijan Democratic Republic declares its independence
1926 - 28th May 1926 coup d'état: Ditadura Nacional is established in Portugal to suppress the unrest of the First Republic.
1930 - The Chrysler Building in New York City officially opens.
1934 - Near Callander, Ontario, the Dionne quintuplets are born to Olivia and Elzire Dionne, later becoming the first quintuplets to survive infancy.
1934 - The Glyndebourne festival in England is inaugurated.
1936 - Alan Turing submits On Computable Numbers for publication.
1937 - The Golden Gate Bridge in San Francisco, California, is officially opened by President Franklin D. Roosevelt in Washington, DC, who pushes a button signaling the start of vehicle traffic over the span.
1937 - Neville Chamberlain becomes British Prime Minister.
1940 - World War II: Belgium surrenders to Germany.
1940 - World War II: Norwegian, French, Polish and British forces recapture Narvik. This is the first allied infantry victory of World War II.
1942 - World War II: in retaliation for the assassination of Reinhard Heydrich, Nazis in Czechoslovakia kill over 1800 people.
1952 - Memphis Kiddie Park opens in Brooklyn, Ohio. The park's Little Dipper roller coaster would become the oldest operating steel roller coaster in North America.
1952 - The women of Greece are given the right to vote.
1955 - Henry Bolte becomes Premier of the state of Victoria.
1961 - Peter Benenson's article "The Forgotten Prisoners" is published in several internationally read newspapers. This will later be thought of as the founding of the human rights organization Amnesty International.
1964 - The Palestine Liberation Organization is formed.
1970 - The formerly united Free University of Brussels officially splits into two separate entities, the French-speaking Université Libre de Bruxelles and the Dutch-speaking Vrije Universiteit Brussel.
1974 - Northern Ireland's power-sharing Sunningdale Agreement collapses following a general strike by loyalists.
1975 - Fifteen West African countries sign the Treaty of Lagos, creating the Economic Community of West African States.
1977 - In Southgate, Kentucky, the Beverly Hills Supper Club is engulfed in fire, killing 165 people inside.
1978 - Second round of the presidential elections in Upper Volta. The election is won by incumbent Sangoulé Lamizana.
1979 - Constantine Karamanlis signs the full treaty of the accession of Greece with the European Economic Community.
1982 - Falklands War: British forces defeat the Argentines at the Battle of Goose Green.
1987 - 19-year-old West German pilot Mathias Rust evades Soviet Union air defenses and lands a private plane in Red Square in Moscow. He is immediately detained and is not released until August 3, 1988.
1987 - A robot probe finds the wreckage of the USS Monitor near Cape Hatteras, North Carolina.
1991 - The capital city of Addis Ababa, falls to the Ethiopian People's Revolutionary Democratic Front, ending both the Derg regime in Ethiopia and the Ethiopian Civil War.
1995 - The Russian town of Neftegorsk is hit by a 7.6 magnitude earthquake that kills at least 2,000 people, ⅔ of total population.
1996 - U.S. President Bill Clinton's former business partners in the Whitewater land deal, James McDougal and Susan McDougal, and Arkansas Governor Jim Guy Tucker, are convicted of fraud.
1998 - Nuclear testing: Pakistan responds to a series of Indian nuclear tests with five of its own, prompting the United States, Japan, and other nations to impose economic sanctions.
1999 - In Milan, Italy, after 22 years of restoration work, Leonardo da Vinci's masterpiece "The Last Supper" is put back on display.
1999 - Two Swedish police officers are murdered with their own fire arms by the bank robbers Jackie Arklöv and Tony Olsson after a dramatic car chase.
2002 - NATO declares Russia a limited partner in the Western alliance.
2003 - Peter Hollingworth becomes the first Governor-General of Australia to resign his office as a result of criticism of his conduct.
2004 - The Iraqi Governing Council chooses Ayad Allawi, a longtime anti-Saddam Hussein exile, to become prime minister of Iraq's interim government.
2008 - The first meeting of the Constituent Assembly of Nepal formally declares Nepal a republic, ending the 240-year reign of the Shah dynasty.