On two occasions, the Eastern (Byzantine) Emperors reunited their church with its Western (Roman Catholic) counterpart, on political motivations and without durable effect. At the Second Council of Lyon in 1274, Emperor Michael VIII aimed to appease the Papacy to keep his "Frankish" adversaries in check, particularly Charles I of Anjou's plans to (re-)invade the Empire; the union was never widely accepted in Constantinople, and was reversed at the Council of Blachernae in 1285 after both Michael and Charles had died. At the Council of Ferrara/Florence in 1438-39, Emperor John VIII negotiated under the threat of Ottoman conquest, but the union agreement was again resisted in Constantinople and only proclaimed by Isidore of Kiev in December 1452, four years after John's death and too late to prevent the fall of Constantinople a few months later.