[1] According to a Byzantine short chronicle compiled in c. 1425, "on 10 June, Wednesday, at the fourth hour after midday, Mihaloğlu attacked Constantinople", thus beginning the siege of the city.

This was supported with men by the Anatolian beyliks of Germiyan and Karaman, who feared a revival of Ottoman power, as well as, according to Doukas, money given by the Byzantine emperor.

Mustafa was thus able to gather a significant army, and in late August or early September laid siege to the Ottoman capital, Bursa.

Byzantine accounts attributed the lifting of the siege to an apparition of the Theotokos upon the city walls, which greatly inspired the defenders.

[1] John Kananos records that: The Romans, although exhausted from fatigue, leapt and were glad… They shouted hymns to the Most Holy Virgin, glorifying her from the depths of their hearts, saying "This is in truth a rich, celebrated, memorable, extraordinary and remarkable miracle worthy of admiration.