Constantinople fell far earlier than 1453, in politics and in culture. The events of 1421-1424 demonstrates the fragile state of the Empire. Constantinople was in the midst of a downward spiral.
Constantinople survived the crisis with its walls intact, yet the Byzantine Empire was shattered and reduced to Constantinople itself and a spattering of land surrounding it. The crisis for survival began with the release of Mustafa, a contender to the Ottoman throne from Constantinople. Byzantium had hoped that support for Mustafa would bear strategic fruit and weaken the Ottoman threat. However, Mustafa was quickly defeated by Murad, who had recently won the Ottoman civil war, emerging as Sultan. This failure in strategic calculation led to the siege of Constantinople, Thessaloniki and the ravaging of the Peloponnese. Byzantine Constantinople was able to withstand the siege on the strength of its land walls and with substantial diplomatic cunning. The Theodosian walls, as well as the resolve of the populace and the leadership of John Palaeologos withstood the siege. Diplomatically, Manuel Palaeologos’ support for a contender to Murad’s throne, as well as Byzantine diplomatic missions to the West allowed for its continued survival. Though Constantinople remained, Byzantium lost most of its territory and significantly Thessaloniki was handed to the Venetians. The Byzantine crisis of 1421-24 was within a wider period of Byzantine decline, and must first be examined within this context.
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