July 4, 1054 – A supernova is seen by Chinese, Arab, and possibly Amerindian observers near the star Zeta Tauri. For several months it remains bright enough to be seen during the day. Its remnants form the Crab Nebula.

July 16, 1054 – Three Roman legates break relations between Western and Eastern Christian Churches through the act of placing an invalidly-issued Papal Bull of Excommunication on the altar of Hagia Sophia during Saturday afternoon divine liturgy. Historians frequently describe the event as the start of the East-West Schism.

July 27, 1054 – Siward, Earl of Northumbria invades Scotland and defeats Macbeth, King of Scotland somewhere north of the Firth of Forth.