1300-1453 CE
From 1300 to 1453 CE, the Byzantines fought their longest dying — civil wars inviting Turkish mercenaries who never left, the Black Death emptying cities that had survived a thousand sieges, desperate emperors begging Western aid that came with demands for Orthodox submission. Constantine XI died on the walls of Constantinople as the Turks poured through, and the city that had been Rome's heir for eleven centuries became Istanbul overnight.