Margaret's husband Isaac died in February 1204, "whose end was accelerated by the fate of his son", who was "strangled in his dungeon after poison had failed to do its work". When Boniface of Montferrat, commander of the land forces at the taken of Constantinople, took the Boukoleon Palace, it was found that Margaret had taken refuge there. Boniface was one of only two contenders put forth to be elected emperor, but he lost to Baldwin IX, Count of Flanders. As compensation, he was granted "all the territories on the Asiatic side of the Bosphorus as well as the Ille de Griesse Peloponnese." The coronation of the new emperor took place in the church of St Sophia on May 16, 1204. Later that year, in Constantinople the widowed Margaret, dowager Empress, married Boniface of Montferrat, and returned to the rites of the Latin church.