1282 - The people of Sicily rebel against the Angevin king Charles I, in what becomes known as the Sicilian Vespers.
1296 - Edward I sacks Berwick-upon-Tweed, during armed conflict between Scotland and England.
1814 - Napoleonic Wars: Sixth Coalition forces march into Paris.
1814 - Murat issues the Rimini Declaration which would later inspire Italian Unification.
1822 - Florida Territory created in the United States.
1842 - Anesthesia is used for the first time in an operation by Dr. Crawford Long.
1844 - One of the most important battles of the Dominican War of Independence from Haiti takes place near the city of Santiago de los Caballeros.
1855 - Origins of the American Civil War: Bleeding Kansas – "Border Ruffians" from Missouri invade Kansas and force election of a pro-slavery legislature.
1856 - The Treaty of Paris is signed, ending the Crimean War.
1858 - Hymen Lipman patents a pencil with an attached eraser.
1863 - Danish prince Wilhelm Georg is chosen as King George of Greece.
1867 - Alaska is purchased for $7.2 million, about 2 cent/acre ($4.19/km²), by United States Secretary of State William H. Seward. The media call this Seward's Folly.
1870 - Texas is readmitted to the Union following Reconstruction.
1870 - Florida territorial government is established.
1885 - The Battle for Kushka triggers the Pandjeh Incident which nearly gives rise to war between the British Empire and Russian Empire.
1909 - The Queensboro Bridge opens, linking Manhattan and Queens.
1910 - The Mississippi Legislature founds The University of Southern Mississippi.
1912 - Sultan Abdelhafid signs the Treaty of Fez, making Morocco a French protectorate.
1939 - First flight of the Australian C.A.C. CA-16 Wirraway.
1939 - The Heinkel He 100 fighter sets a world airspeed record of 463 mph.
1940 - Sino-Japanese War: Japan declares Nanking to be the capital of a new Chinese puppet government, nominally controlled by Wang Ching-wei.
1945 - World War II: Soviet Union forces invade Austria and take Vienna; Polish and Soviet forces liberate Gdańsk.
1945 - World War II: a defecting German pilot delivers a Messerschmitt Me 262A-1 to the Americans.
1949 - A riot breaks out in Austurvöllur square in Reykjavík, when Iceland joins NATO.
1954 - Yonge Street subway line opens in Toronto. It is the first subway in Canada.
1961 - The Single Convention on Narcotic Drugs is signed at New York.
1965 - Vietnam War: A car bomb explodes in front of the U.S. Embassy in Saigon, killing 22 and wounding 183 others.
1972 - Vietnam War: The Easter Offensive begins after North Vietnamese forces cross into the Demilitarized Zone (DMZ) of South Vietnam.
1979 - Airey Neave, a British politician, is killed by a car bomb as he exits the Palace of Westminster. The Irish National Liberation Army claims responsibility.
1981 - President Ronald Reagan is shot in the chest outside a Washington, D.C., hotel by John Hinckley, Jr.
1982 - Space Shuttle program: STS-3 Mission is completed with the landing of Columbia at White Sands Missile Range, New Mexico.
2006 - The United Kingdom Terrorism Act 2006 becomes law.
240 BC - 1st recorded perihelion passage of Halley's Comet.