- 1581 Francis Drake knighted by Queen Elizabeth I aboard Golden Hind at Deptford
- 1655 Battle at Postage Farina, Tunis: English fleet beats Barbary pirates
- 1949 North Atlantic Treaty Organization (NATO) treaty signed in Washington DC
- 1968 US civil rights activist Martin Luther King Jr. assassinated in Memphis, Tennessee
- 1975 Microsoft is founded as a partnership between Bill Gates and Paul Allen.
Congress decides on the US flag: 13 red & white stripes & 20 stars
On April 4, 1818