 Complete the following phrase:  His father Theodore ruled over the Byzantine successor state of Epirus since 1215, and after the conquest of the Latin Kingdom of Thessalonica in 1224, had founded the Empire of Thessalonica, in rivalry with the other major Byzantine successor state, the Empire of Nicaea in western Asia Minor. By 1230, he seemed poised to recover Constantinople from the Latin Empire and thus restore the Byzantine Empire, but in that year he was defeated and captured at the 