In January 1459, rivalry between the brothers broke out into civil war as Thomas, with the aid of some of the Albanian lords in the Morea, seized a series of fortresses held by Demetrios. The ongoing civil war, and the possibility that Thomas could receive aid from the West since he had proclaimed the war against his brother as a holy war against the muslims, caused Mehmed to invade the Morea in 1460. Mehmed was victorious and annexed the region directly into the Ottoman Empire, ending Palaiologan rule in Greece. Demetrios surrendered to the Ottomans without a fight and Thomas escaped into exile. Demetrios lived in the Ottoman Empire for the rest of his life, dying in 1470. His only child, his daughter Helena, never married the sultan nor entered the sultan's harem, possibly because the sultan feared that she would poison him. She predeceased her father, dying in 1469.