Wikipedia:Selected anniversaries/April 23
April 23: Easter in Eastern Christianity (2006); World Book Day; National Sovereignty and Children's Day in Turkey; St George's Day in various countries.
- 1014 - Irish forces led by Brian Boru (pictured) clashed with the Vikings in the Battle of Clontarf.
- 1827 - Irish mathematician and physicist Rowan Hamilton presented his Theory of Systems of Rays.
- 1923 - Gdynia was inaugurated as a Polish seaport on the south coast of the Baltic Sea.
- 1954 - Batting against Vic Raschi of the St. Louis Cardinals, Hank Aaron of the Milwaukee Braves hit the first of his 755 home runs in Major League Baseball.
- 1982 - The Conch Republic facetiously declared independence from the United States.