Constantine XI Palaeologus (born February 9, 1404, Constantinople, Eastern Roman Empire — died May 29,1453,Constantinople),the last Roman Emperor (1449–1453), killed in the final defense of Constantinople against the Ottoman Turks.

Constantine XI Palaeologus (born February 9, 1404, Constantinople, Eastern Roman Empire — died May 29,1453,Constantinople),the last Roman Emperor (1449–1453), killed in the final defense of Constantinople against the Ottoman Turks.

Constantine XI was the fourth son of the Emperor Manuel II and his Serbian wife,Helen.He spent his early career with his brothers Theodore and Thomas governing the Byzantine Despotate of Morea (Peloponnese) and completing its reconquest from the Franks.

When his brother John VIII Palaeologus died childless in 1448, he was proclaimed Emperor at Mistra (January 1449).He was a man of courage and energy, but he succeeded to a ruinous inheritance.Mehmed II,who became Ottoman sultan in 1451,directed all his resources to the capture of Constantinople.Constantine did everything within his power to organize the defense of the city and to enlist the support of the West by acknowledging the obedience of the Church to Rome,but in vain.He was killed fighting at the city walls when the Turks finally broke through.