Wikipedia:Selected anniversaries/August 12
- 1099 - The First Crusade concluded with the Battle of Ascalon, and Fatimid forces under Al-Afdal Shahanshah retreating to Egypt.
- 1676 - John Alderman shot and killed Metacomet the Wampanoag war chief, ending King Philip's War.
- 1851 - Isaac Singer was granted a patent for his sewing machine.
- 1953 - History of nuclear weapons: The first Soviet thermonuclear bomb, Joe 4, was detonated at Semipalatinsk, Kazakhstan.
- 1985 - Japan Airlines Flight 123 crashed in Gunma Prefecture, Japan, killing 520 of 524 on board in the world's worst single-aircraft aviation disaster.