April 19 – Emperor Michael V Kalaphates banishes his adoptive mother and co-ruler Zoë, for plotting to poison him, to the island of Principo. His announcement as sole emperor leads to a popular revolt.
April 20 – Zoë is proclaimed as empress at an assembly in Hagia Sophia, along with her sister Theodora, as co-ruler. Michael V flees to the monastery of Stoudios, but is arrested, blinded and castrated.
June 11 – Zoë marries her third husband, a Byzantine bureaucrat who ascends as co-emperor Constantine IX at Constantinople. Theodora agrees to surrender her co-emperorship.
Summer – George Maniakes goes on a march through Apulia, plundering the towns that have declared for the Lombard rebels. Constantine IX recalls Maniakes to Constantinople.
George Maniakes revolts against Constantine IX and is declared emperor by his troops. He captures Pardos who has landed with an army at Otranto to take over his command.
Byzantine–Arab War: The Byzantines reconquer the fortress city of Edessa (modern Turkey), returning it to Christian hands, after 400 years of Islamic rule (approximate date).
Duklja secures its independence from the Byzantine Empire.
June 8 – Magnus the Good becomes king of Denmark after the death of Harthacnut. Despite a claim to the throne by Sweyn II, Magnus takes control of Denmark.
