Combined Bulgarian and Cuman army under Kalojan ambushes and defeats forces of the Latin Empire of Constantinople in the Battle of Adrianople.

Kaloyan or Kalojan, also known as Ivan I, Ioannitsa or Johannitsa, the Roman Slayer, was emperor or tsar of Bulgaria from 1196 to 1207. He was the younger brother of Theodor and Asen, who led the anti-Byzantine uprising of the Bulgarians and Vlachs in 1185. The uprising ended with the restoration of Bulgaria as an independent state. He spent a few years as a hostage in Constantinople in the late 1180s. Theodor, crowned Emperor Peter II, made him his co-ruler after Asen was murdered in 1196. A year later, Peter was also murdered, and Kaloyan became the sole ruler of Bulgaria.