- 1707 - The Act of Union joins the Kingdom of England and Kingdom of Scotland to form the Kingdom of Great Britain.
- 1834 - The British colonies abolish slavery.
- 1863 - American Civil War: The Battle of Chancellorsville begins.
- 1898 - Spanish-American War: The Battle of Manila Bay - the United States Navy destroys the Spanish Pacific fleet in the first battle of the war.
- 1930 - The dwarf planet Pluto is officially named.
- 1931 - The Empire State Building is dedicated in New York City.
- 1945 - World War II: A German newsreader officially announces that Adolf Hitler has "fallen at his command post in the Reich Chancellery fighting to the last breath against Bolshevism and for Germany".
- 1948 - The Democratic People's Republic of Korea (North Korea) is established, with Kim Il-sung as president.
- 1950 - Guam is organized as a United States commonwealth.
- 1960 - Cold War: U-2 Crisis – Francis Gary Powers, in a Lockheed U-2 spyplane, is shot down over the Soviet Union, sparking a diplomatic crisis.
- 1961 - The Prime Minister of Cuba, Fidel Castro, proclaims Cuba a socialist nation and abolishes elections.
- 2004 - Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia join the European Union.