He is chiefly known for two brilliant campaigns by which he recovered Thrace from the Bulgarians (1255-1256). His ill-health and early death prevented his making full use of his ability as a ruler.
TheodoreLascaris, the son-in-law of Emperor Alexius III, was proclaimed emperor, but he too fled, to the city of Nicaea in Bithynia, realizing the situation in Constantinople was hopeless.
TheodoreLascaris was not immediately successful, as he was defeated at Poemanenum and Bursa in 1204, but he was able to capture much of northwestern Anatolia after the Latin Emperor Baldwin I had to defend against invasions from Kaloyan of Bulgaria.
TheodoreIILascaris, John IIIs son, faced invasions from the Bulgarians in Thrace, but successfully defended the territory.