Events

• April 16 - Philip II of France enters Rouen, leading to the eventual unification of Normandy and France.
• June 23 - Fleet of the Fourth Crusade enters Bosphorus
• July 17 - Fourth Crusade captures Constantinople by assault; the Byzantine emperor Alexius III flees from his capital into exile.
• August 1 - Fourth Crusade elevates Alexius IV as Byzantine emperor, after the citizens of Constantinople proclaim as emperor Isaac II Angelus (Alexius IV's father).
• William de Braose, Fourth Lord of Bramber becomes the guardian of Arthur I, Duke of Brittany, and is possibly responsible for his death.
• Minamoto no Sanetomo becomes shogun of the Kamakura Shogunate

Births

• Peter II of Savoy

Deaths

• Arthur I, Duke of Brittany

Heads of states

• France - Philippe II, Auguste King of France (reigned from 1180 to 1223)