In one battle, this man was relieved by ships commanded by Francesco Lecanella, who landed despite attacks from Admiral (*) Baltoghlu.
It took just five days for this man's rebuilt Hexamilion Wall to collapse to enemy forces. While serving as Despot of Morea, this man defeated Nerio II Acciajuoli and took Athens. Johannes Grant headed counter-mining operations for this ruler. This man sent Andronicus Leontaris to drum up support for his reign in the west. In one battle, this man was relieved by ships commanded by Francesco Lecanella, who landed despite attacks from Admiral (*) Baltoghlu. That same battle saw him order a giant chain to close the Golden Horn. He succeeded John VIII and died in 1453 after his city fell to Mehmed II. For 10 points, name this final Byzantine emperor.
It took just five days for this man's rebuilt Hexamilion Wall to collapse to enemy forces.
Constantine XI Palaiologos [or Constantine XI Palaeologus]