Portal:War/Selected anniversaries/May 23
- 1430 - Joan of Arc is captured by the Burgundians while leading an army to relieve Compiègne
- 1568 - Dutch rebels led by Louis of Nassau, brother of William I of Orange, defeat Jean de Ligne, Duke of Aremberg and his loyalist troops in the Battle of Heiligerlee, opening the Eighty Years' War.
- 1618 - The Second Defenestration of Prague precipitates the Thirty Years' War.
- 1863 - The Siege of Port Hudson starts.
- 1900 - American Civil War: Sergeant William Harvey Carney becomes the first African American to be awarded the Medal of Honor, for his heroism in the assault on the Battery Wagner.
- 1915 - World War I: Italy joins the Allies after they declare war on Austria-Hungary.
- 1945 - World War II: The Flensburg government under Reichspräsident Karl Dönitz was dissolved when its members were captured and arrested by British forces at Flensburg in Northern Germany.