- 528 - Byzantine Emperor Justin II named Justinian I as co-ruler and successor.
- 1790 - The U.S. House of Representatives held its first quorum in New York City and elected Frederick Muhlenberg as the first Speaker.
- 1828 - The internal combustion engine was patented by Samuel Morey.
- 1865 - Confederate General Robert E. Lee began his final offensive.
- 1924 - Adolf Hitler is sentenced to nine years in jail for his participation in the "Beer Hall Putsch." However, he spends only five months in jail, during which he writes the book My Struggle.
- 1945 - World War II: The Battle of Okinawa, the largest amphibious assault during the Pacific campaign, began in Okinawa, Japan.
- 1949 - Newfoundland joined Canada.
- 1979 - Iran was proclaimed an Islamic republic, a theocracy led by Ayatollah Ruhollah Khomeini as the Supreme Leader of Iran.
- 2001 - The Netherlands legalizes euthanasia, becoming the only nation in the world to do so.