Thomas was the son of Nikephoros I Komnenos Doukas and Anna Palaiologina Kantakouzene, a niece of Emperor Michael VIII Palaiologos. In 1290 he was conferred the court dignity of despotes by his mother"s cousin, Emperor Andronikos II Palaiologos. Thomas" succession to his father"s principality was endangered by the marriage of his sister Thamar Angelina Komnene to Philip I of Taranto, a son of King Charles II of Naples and Maria of Hungary in 1294.
This isolated Epirus from its strongest ally and left it practically without outside support. Charles II of Naples demanded that Epirus be turned over to Philip and Thamar, but Anna refused, claiming that the arrangement had been broken when Thamar had been forced to abandon her Orthodox faith. The actual marriage took place in 1307 or 1313.
In the meantime Charles II sent troops into Epirus, but they were repulsed and the Epirotes advanced into the Angevin lands in the western Balkans, recovering Butrinto and Naupaktos in 1304–1305.
A new Angevin invasion in 1307 ended with a compromise by which Philip of Taranto was ceded many of the fortresses that had been retaken by the Epirotes in the previous war. Epirus gravitated increasingly into the Byzantine orbit until a private dispute between Epirote and Byzantine commanders sparked off a new conflict in 1315.
