- 1606 12 Apr The combined English-Scottish 'Union Jack' is created by royal decree, originally for use at sea only.
- 1861 12 Apr The first shots of the American Civil War are fired as the Confederates take Fort Sumter, South Carolina.
- 1961 12 Apr Soviet cosmonaut Yuri Gagarin becomes the first man in space, aboard the spacecraft Vostok 1.

