823

By place

Byzantine Empire

• Emperor Michael II defeats the rebel forces under Thomas the Slav in Thrace. He and his supporters are forced to seek refuge in Arkadiopolis. After five months of blockade, Thomas surrenders and is delivered to Michael, seated on a donkey and bound in chains. He pleads for clemency and prostrates before Michael, but is executed.

  Europe

• April 5 - Lothair I, eldest son of Emperor Louis I, is crowned co-emperor again by Pope Paschal I at Rome.

  Britain

• King Ceolwulf I of Mercia is deposed by Beornwulf, who takes the throne of Mercia. During his rule he rebuilds the Abbey of St. Peter, and presides over two synods at Clofesho.

  Japan

• May 30 - Emperor Saga abdicates the throne, after a 10-year reign. He is succeeded by his brother Junna, as the 53rd emperor of Japan.