Michael I Komnenos Doukas was assassinated in late 1214 or in 1215. Theodore Komnenos Doukas, who succeeded him, questioned Theodore Laskaris's claim to supremacy, ignoring his previous oath of fealty. In concert with Demetrios Chomatenos, the ambitious Archbishop of Ochrid, Doukas denied the right of the patriarch residing in Nicaea to appoint bishops to the Balkan episcopal sees under Epirote control. Doukas's expansionist policy forced Emperor Henry to launch a military campaign against him, but Henry died unexpectedly before reaching Epirus. The Latin barons elected his brother-in-law, Peter of Courtenay, as his successor, but he was captured and killed in Epirus during his journey towards Constantinople in 1217. A lasting vacancy followed his death, with his widow, Yolanda of Flanders, ruling the Latin Empire as regent. She gave her daughter, Maria of Courtenay, in marriage to Theodore who agreed to prolong his peace treaty with the Latin Empire.