Siege of Constantinople (1411)

The Siege of Constantinople of 1411 occurred during the Ottoman Interregnum, or Ottoman Civil War, (20 July 1402 – [5 July 1413), when chaos reigned in the Ottoman Empire following the defeat of Sultan Bayezid I by the Central Asian warlord Timur. Although Mehmed Çelebi was confirmed as sultan by Timur after the Battle of Ankara, his brothers İsa Çelebi, Musa Çelebi, Süleyman Çelebi, and later, Mustafa Çelebi, refused to recognize his authority, each claiming the throne for himself. A civil war was the result. The Interregnum lasted until the Battle of Camurlu on 5 July 1413, when Mehmed Çelebi emerged as victor in the strife, crowned himself sultan Mehmed I, and restored peace to the empire.

Background
Before the Battle of Ankara, the Byzantine Empire was a mere pawn of outside forces for several decades but after the defeat of the Ottomans by Timur, the Empire - for a short while, became a player in Ottoman domestic politics and intrigue.

The siege
The Byzantine Emperor Manuel II Palaiologos supported Süleyman as claimant to the Ottoman throne. They signed the treaty of Gelibolu with the Byzantine regent John VII Palaiologos in 1403, as the emperor Manuel II Palaiologos was traveling in western Europe at the time. By this treaty, Süleyman gave up certain territories along the Marmara coast to the Byzantine Empire in return for Byzantine support during the interregnum and declared himself sultan of the empire in Edirne, the capital in Rumeli of the Ottoman Empire.

However, Musa defeated Süleyman at the battle of Kosmidion in 1410 and Musa pursued him following his escape. Süleyman was captured, while attempting to escape to Byzantine territories, was killed by villagers on February 18, 1411 and Musa found himself as the co-sultan of the European portion of the empire. Musa then retaliated against all who allied with Süleyman, including Manuel II by laying siege to Constantinople in 1411. Manuel II turned to Mehmet for support, who betrayed Musa and set up a new alliance between himself and the Byzantines against Musa. The siege was lifted sometime during the same year.

In two major engagements, in 1411 and in 1412, Mehmet's forces clashed with Musa's, and in both cases Musa was defeated, lifting the siege of Constantinople. In 1413, Mehmet gained the support of the Serbian monarch Stefan Lazarević and the bey of the Turkish Dulkadirids, as well as some of the generals in Musa's army. He defeated Musa's forces in the Battle of Çamurlu near Samokov, Bulgaria. Injured and trying to escape, Musa was spotted and killed on July 5, 1413.