- 1618 Second Defenestration of Prague: Two Catholic Lords Regent and their secretary are thrown out of a window and amazingly are not seriously injured by the 70 foot (21m) fall. Triggers the Thirty Years' War.
- 1785 Benjamin Franklin announces his invention of bifocals
- 1813 South American independence leader Simón Bolívar enters Mérida, leading the invasion of Venezuela, and is proclaimed El Libertador ("The Liberator")
- 1949 Federal Republic of [West] Germany created out of the American, British and French occupation zones
- 1958 Mao Zedong starts the "Great Leap Forward" movement in China
- 1998 The Good Friday Agreement is accepted in a referendum in Northern Ireland with 75% voting yes.
Canada's North West Mounted Police Force forms (it didn't get the "Royal" until 1904)
On May 23, 1873
Baseball game between one-armed and one-legged players at Recreation Park, Philadelphia, Snorkeys defeat the Hoppers 33-17
On May 23, 1883