On this day... July 29:

904 – Sack of Thessalonica: Saracen raiders under Leo of Tripoli sack Thessaloniki, the Byzantine Empire's second-largest city, after a short siege, and plunder it for a week.

1014 – Byzantine–Bulgarian Wars: Battle of Kleidion – Byzantine emperor Basil II inflicts a decisive defeat on the Bulgarian army, and his subsequent treatment of 15,000 prisoners reportedly causes Tsar Samuil of Bulgaria to die of a heart attack less than three months later, on October 6.

1018 – Count Dirk III defeats an army sent by Emperor Henry II in the Battle of Vlaardingen.

1030 – Ladejarl-Fairhair succession wars: Battle of Stiklestad – King Olaf II fights and dies trying to regain his Norwegian throne from the Danes.

1148 – The Siege of Damascus ends in a decisive crusader defeat and leads to the disintegration of the Second Crusade.