The Bulgarian-Wallachian Empire and the Crusaders during the reign of the Tsar Boril Asen (1207-1218). From armed conflict to the political and military collaboration

The reign of Tsar Boril Asen (1207-1218) represents a crucial stage in the development of relations between the Bulgarian-Wallachian Empire and the Catholic powers, supporters of the crusades: The Latin Empire of Constantinople, the Kingdom of Thessalonica, Hungary and the Holy See. Under the pressure of a difficult international environment, these relationships have changed from a political dispute and armed conflict to the military-political alliance. In the relationship between the Second Bulgarian Empire and Crusader States there are two distinct periods: a) 1208-1213/1214, a stage of the conflict, marked by strong political tensions and military confrontation; b) 1213/1214-1218, a period of collaboration, marked by the entry of the State of Asens into the camp of Catholic powers and the conclusion of the military-political alliances.