The first full-scale Ottoman siege of Constantinople took place in 1422 as a result of the Byzantine Emperor Manuel II's attempts to interfere in the succession of Ottoman Sultans, after the death of Mehmed I in 1421. This policy of the Byzantines was often used successfully in weakening their neighbours.

When Murad II emerged as the winning successor to his father, he marched into Byzantine territory. The Turks had acquired their own cannon for the first time by the siege of 1422, "falcons", which were short but wide cannons. The two sides were evenly matched technologically, and the Turks had to build barricades "in order to receive ... the stones of the bombards".