495 BC – A newly constructed temple in honour of the god Mercury was dedicated in ancient Rome on the Circus Maximus, between the Aventine and Palatine hills. To spite the senate and the consuls, the people awarded the dedication to a senior military officer, Marcus Laetorius.
221 – Liu Bei, Chinese warlord, proclaims himself emperor of Shu Han, the successor of the Han dynasty.
392 – Emperor Valentinian II is assassinated while advancing into Gaul against the Frankish usurper Arbogast. He is found hanging in his residence at Vienne.
589 – King Authari marries Theodelinda, daughter of the Bavarian duke Garibald I. A Catholic, she has great influence among the Lombard nobility.
908 – The three-year-old Constantine VII, the son of Emperor Leo VI the Wise, is crowned as co-emperor of the Byzantine Empire by Patriarch Euthymius I at Constantinople.
1252 – Pope Innocent IV issues the papal bull ad extirpanda, which authorizes, but also limits, the torture of heretics in the Medieval Inquisition.
1525 – Insurgent peasants led by Anabaptist pastor Thomas Müntzer were defeated at the Battle of Frankenhausen, ending the German Peasants' War in the Holy Roman Empire.
1536 – Anne Boleyn, Queen of England, stands trial in London on charges of treason, adultery and incest; she is condemned to death by a specially-selected jury.
1567 – Mary, Queen of Scots marries James Hepburn, 4th Earl of Bothwell, her third husband.
1618 – Johannes Kepler confirms his previously rejected discovery of the third law of planetary motion (he first discovered it on March 8 but soon rejected the idea after some initial calculations were made).
1648 – The Treaty of Westphalia is signed.
1718 – James Puckle, a London lawyer, patents the world's first machine gun.
1730 – Robert Walpole effectively became the first Prime Minister of the United Kingdom.
1776 – American Revolution: The Fifth Virginia Convention instructs its Continental Congress delegation to propose a resolution of independence from Great Britain, paving the way for the United States Declaration of Independence.
1791 – French Revolution: Maximilien Robespierre proposes the Self-denying Ordinance.
1792 – War of the First Coalition: France declares war on Kingdom of Sardinia.
1793 – Diego Marín Aguilera flies a glider for "about 360 meters", at a height of 5–6 meters, during one of the first attempted manned flights.
1796 – War of the First Coalition: Napoleon enters Milan in triumph.
1800 – King George III of the United Kingdom survives an assassination attempt by James Hadfield, who is later acquitted by reason of insanity.
1811 – Paraguay declares independence from Spain.
1817 – Opening of the first private mental health hospital in the United States, the Asylum for the Relief of Persons Deprived of the Use of Their Reason (now Friends Hospital, Philadelphia, Pennsylvania).
1836 – Francis Baily observes "Baily's beads" during an annular eclipse.
1848 – Serfdom is abolished in the Habsburg Galicia, as a result of the 1848 revolutions. The rest of monarchy followed later in the year.
1849 – Troops of the Two Sicilies take Palermo and crush the republican government of Sicily.
1850 – The Bloody Island massacre takes place in Lake County, California, in which a large number of Pomo Indians are slaughtered by a regiment of the United States Cavalry.
1850 – The Arana–Southern Treaty is ratified, ending "the existing differences" between Great Britain and Argentina.
1851 – The first Australian gold rush is proclaimed, although the discovery had been made three months earlier.
1858 – Opening of the present Royal Opera House in Covent Garden, London.
1862 – President Abraham Lincoln signs a bill into law creating the United States Bureau of Agriculture. It is later renamed the United States Department of Agriculture.
1864 – American Civil War: Battle of New Market, Virginia: Students from the Virginia Military Institute fight alongside the Confederate Army to force Union General Franz Sigel out of the Shenandoah Valley.
1869 – Women's suffrage: In New York, Susan B. Anthony and Elizabeth Cady Stanton form the National Woman Suffrage Association.
1891 – Pope Leo XIII defends workers' rights and property rights in the encyclical Rerum novarum, the beginning of modern Catholic social teaching.
1904 – Russo-Japanese War: The Russian minelayer Amur lays a minefield about 15 miles off Port Arthur and sinks Japan's battleships Hatsuse, 15,000 tons, with 496 crew and Yashima.
1905 – Las Vegas is founded when 110 acres (0.45 km2), in what later would become downtown, are auctioned off.
1911 – In Standard Oil Co. of New Jersey v. United States, the United States Supreme Court declares Standard Oil to be an "unreasonable" monopoly under the Sherman Antitrust Act and orders the company to be broken up.
1911 – More than 300 Chinese immigrants are killed in the Torreón massacre when the forces of the Mexican Revolution led by Emilio Madero take the city of Torreón from the Federales.
1919 – The Winnipeg general strike begins. By 11:00, almost the whole working population of Winnipeg had walked off the job.
1919 – Greek occupation of Smyrna. During the occupation, the Greek army kills or wounds 350 Turks; those responsible are punished by Greek commander Aristides Stergiades.
1925 – Al-Insaniyyah, the first Arabic communist newspaper, is founded.
1928 – Walt Disney character Mickey Mouse premieres in his first cartoon, "Plane Crazy".
1929 – A fire at the Cleveland Clinic in Cleveland, Ohio kills 123.
1932 – In an attempted coup d'état, the Prime Minister of Japan Inukai Tsuyoshi is assassinated.
1933 – All military aviation organizations within, or under the control of, the RLM of Germany were officially merged in a covert manner, to form its Wehrmacht military's air arm, the Luftwaffe.
1934 – Kārlis Ulmanis establishes an authoritarian government in Latvia.
1940 – USS Sailfish is recommissioned. It was originally the USS Squalus.
1940 – World War II: After fierce fighting, the poorly trained and equipped Dutch troops surrender to Germany, marking the beginning of five years of occupation.
1940 – McDonald's opens its first restaurant in San Bernardino, California.
1941 – First flight of the Gloster E.28/39 the first British and Allied jet aircraft.
1941 – Joe DiMaggio begins a 56-game hitting streak.
1942 – World War II: In the United States, a bill creating the Women's Army Auxiliary Corps (WAAC) is signed into law.
1943 – Joseph Stalin dissolves the Comintern (or Third International).
1945 – World War II: The Battle of Poljana, the final skirmish in Europe is fought near Prevalje, Slovenia.
1948 – Following the expiration of The British Mandate for Palestine, the Kingdom of Egypt, Transjordan, Lebanon, Syria, Iraq and Saudi Arabia invade Israel thus starting the 1948 Arab–Israeli War.
1957 – At Malden Island in the Pacific Ocean, Britain tests its first hydrogen bomb in Operation Grapple.
1958 – The Soviet Union launches Sputnik 3.
1960 – The Soviet Union launches Sputnik 4.
1963 – Project Mercury: The launch of the final Mercury mission, Mercury-Atlas 9 with astronaut Gordon Cooper on board. He becomes the first American to spend more than a day in space, and the last American to go into space alone.
1966 – After a policy dispute, Prime Minister Nguyễn Cao Kỳ of South Vietnam's ruling junta launches a military attack on the forces of General Tôn Thất Đính, forcing him to abandon his command.
1969 – People's Park: California Governor Ronald Reagan has an impromptu student park owned by the University of California at Berkeley fenced off from student anti-war protestors, sparking a riot.
1970 – President Richard Nixon appoints Anna Mae Hays and Elizabeth P. Hoisington the first female United States Army generals.
1970 – Philip Lafayette Gibbs and James Earl Green are killed at Jackson State University by police during student protests.
1972 – Ryukyu Islands, under U.S. military governance since its conquest in 1945, hand over to Japanese control.
1972 – In Laurel, Maryland, Arthur Bremer shoots and paralyzes Alabama Governor George Wallace while he is campaigning to become President.
1974 – Ma'alot massacre: Members of the Democratic Front for the Liberation of Palestine attack and take hostages at an Israeli school; a total of 31 people are killed, including 22 schoolchildren.
1987 – The Soviet Union launches the Polyus prototype orbital weapons platform. It fails to reach orbit.
1988 – Soviet war in Afghanistan: After more than eight years of fighting, the Soviet Army begins to withdraw 115,000 troops from Afghanistan.
1991 – Édith Cresson becomes France's first female premier.
1997 – The United States government acknowledges the existence of the "Secret War" in Laos and dedicates the Laos Memorial in honor of Hmong and other "Secret War" veterans.