The Battle of Pelagonia

In 1211, Tsar Boril decided to renew his war against the Latin Empire and, with support from his brother, Sebastokrator Strez, attack the Kingdom of Thessalonica. The combined forces of the crusaders and Despot Alexios Slav, however, seized the initiative and advanced towards Prosek. The two armies clashed on the Bitola Plain, also known as Pelagonia.

At the Battle of the Bitola Plain, the Bulgarians under Boril were defeated by the combined forces of the crusaders and Despot Alexios Slav.