• 467 - Anthemius is elevated to Emperor of the Western Roman Empire.
• 1557 - Cuenca is founded in Ecuador.
• 1606 - The Union Flag is adopted as the flag of Great Britain.
• 1633 - The formal inquest of Galileo Galilei by the Inquisition begins.
• 1776 - North Carolina's Provincial Congress authorizes its delegates to the Second Continental Congress to vote for independence by issuing the Halifax Resolves.
• 1820 - Alexander Ypsilantis is declared leader of Filiki Eteria, a secret organization to overthrow Ottoman rule over Greece.
• 1861 - American Civil War: The war begins with Confederate forces firing on Fort Sumter, in the harbor of Charleston, South Carolina.
• 1864 - American Civil War: The Fort Pillow massacre: Confederate forces under General Nathan Bedford Forrest kill most of the African American soldiers who had surrendered at Fort Pillow, Tennessee.
• 1865 - American Civil War: Mobile, Alabama, falls to the Union Army.
• 1877 - The United Kingdom annexes the Transvaal.
• 1917 - World War I: Canadian forces successfully complete the taking of Vimy Ridge from the Germans. It is also considered a major event in Canadian history for the primary role Canadian forces played in the attack.
• 1927 - April 12 Incident: Chiang Kai-shek orders the CPC members executed in Shanghai, ending the First United Front.
• 1934 - The strongest surface wind gust in the world at 231 mph, is measured by the staff of the Mount Washington Observatory on the summit of Mount Washington.
• 1934 - The Auto-Lite Strike, which culminated in a five-day melee between Ohio National Guard troops and 6,000 strikers and picketers, begins.
• 1935 - First flight of the Bristol Blenheim.
• 1937 - Sir Frank Whittle ground-tests the first jet engine designed to power an aircraft, at the British Thomson-Houston factory in Rugby, England.
• 1945 - President Franklin D. Roosevelt dies while in office; vice-president Harry Truman is sworn in as the 33rd President of the United States.
• 1955 - The polio vaccine, developed by Dr. Jonas Salk, is declared safe and effective.
• 1961 - Human spaceflight: Yuri Gagarin becomes the first human to travel into outer space in Vostok 3KA-2 (Vostok 1).
• 1963 - The Soviet nuclear powered submarine K-33 collides with the Finnish merchant vessel M/S Finnclipper in the Danish straits. Although both vessels are severely damaged both made it to port.
• 1968 - Nerve gas accident at Skull Valley, Utah.
• 1980 - Samuel Doe takes control of Liberia in a coup d'etat, ending over 130 years of democratic presidential succession in that country.
• 1980 - Terry Fox begins his "Marathon of Hope" by dipping his artificial leg into the Atlantic at St. John's, Newfoundland.
• 1981 - Human spaceflight: The first launch of a Space Shuttle: Columbia launches on the STS-1 mission.
• 1990 - Opening of Jim Gary's Twentieth Century Dinosaurs exhibition, the work of the only living sculptor ever invited to present a solo exhibition at the Smithsonian Institution National Museum of Natural History in Washington, D.C.
• 1992 - Disneyland Resort Paris opens in the eastern suburbs of Paris, France, and is the second international Disney resort property.
• 1994 - Canter & Siegel post the first commercial mass Usenet spam.
• 1998 - An earthquake in Slovenia, measuring 5.6 on the Richter scale takes place near the town of Bovec.
• 1999 - U.S. President Bill Clinton is cited for contempt of court for giving "intentionally false statements" in the Paula Jones sexual harassment civil lawsuit.
• 2002 - Pedro Carmona becomes interim President of Venezuela during the Venezuelan coup attempt of 2002, a military coup against Hugo Chávez.

Births