Kaloyan of Bulgaria
Theodore Lascaris was not immediately successful, as Henry of Flanders defeated him at Poimanenon and Prusa (now Bursa) in 1204. But Theodore was able to capture much of northwestern Anatolia after the Bulgarian defeat of Latin Emperor Baldwin I in the Battle of Adrianople, because Henry was recalled to Europe to defend against invasions from Tsar Kaloyan of Bulgaria. Theodore also defeated an army from Trebizond, as well as other minor rivals, leaving him in charge of the most powerful of the successor states. In 1206, Theodore proclaimed himself emperor at Nicaea.