Mustafa Çelebi

The descendants of the Turkmen notables who had assisted the early Ottoman conquests in Europe support the claims of Mehmed, who rules in Amasya.

With the additional support of the Anatolian Muslim religious orders and artisan guilds…

…Mehmed is able to defeat and strangle his brother Isa Bey of Balikesir in southwestern Anatolia, and seize Bursa.

He now sends another brother, Mûsa Bey, against Süleyman.

The Ottoman Interregnum continues into its second decade, as the sons of the late Sultan Bayezid fight for control of the empire.

Musa has the support of Wallachians and Serbs and Süleyman has the support of Constantinople, but the Serbs change sides and Musa is defeated in the Battle of Kosmidion on June 15, 1410.

Suleyman is a weak prince, however, and to the dismay of his partisans, he begins living in extravagance.

Mûsa leads Turks and Wallachians against his brother Süleyman, having coaxing Süleyman's Serbian and Bulgarian Janissaries over to his side.

Süleyman’s indifference to state affairs has caused him to lose supporters, especially after the death of his able vizier Çandarlı Ali Pasha.

Thus, when Musa marches to Edirne in 1411, Süleyman has almost no one at his side.

He tries to escape to imperial Greek territories, but Musa captures him and orders his strangulation on February 17, 1411.

Musa now declares himself sultan in Edirne and undertakes the reconquest of the Ottoman territories in Rumelia.

Bedreddin, a convert to Sufism (Islamic mysticism) who had in 1383 undertaken the pilgrimage to Mecca, and, upon his return to Cairo, had been appointed tutor to the Mamluk crown prince of Egypt, had then traveled as a Sufi missionary throughout Asia Minor; his communalistic doctrines have made him a popular preacher.

Mûsa now appoints Bedreddin chief military judge.

Mûsa again besieges Constantinople.

An avenger appears, however, in the person of Mehmed, Bayezid's youngest son.

Backed by powerful non-Ottoman Turkish notables and allied to the Greeks, Mehmed helps to lift Mûsa's siege, wins the Janissaries to his cause, and fights Mustafa twice before …

…defeating him a third time at Camurlu, capturing him, and ordering his strangulation in 1413.

Mustafa, a surviving brother of Mehmed I, appears in Rumelia with the help of Emperor Manuel II Palaiologos.

He also has the support of Mircea I of Wallachia and Cüneyt Bey of Aydın (ruler of the Aydinid principality).

Mustafa asked Mehmed I, who had recently defeated other claimants, to partition the empire, but he had been refused and was easily defeated by the forces of Mehmed.

He takes refuge in 1416 in the imperial Greek city of Thessaloniki.

Manuel, after reaching an agreement with Mehmed, sends Mustafa to the island of Lemnos.

Emperor Manuel II Palaiologos withdraws from state affairs to pursue his religious and literary interests.

His son John VIII, crowned co-emperor in 1421, ignores the tenuous bond with the Ottomans that has been established and in this year supports the pretender Mustafa against the rightful heir to the Turkish throne, Murad II, in hope of causing disruption within the ranks and leadership of the Ottoman Empire.

However, …

…Murad is placed on the throne by non-Ottoman but politically powerful Turkish notables who had joined the Ottoman state during the first century of its existence.

Murad, only eighteen when he becomes sultan, soon begins to resent the power they have gained in return.

He counters by beginning to build up the power of various non-Turkish groups in his service, particularly those composed of Christian slaves and converts to Islam, whose military arm is the Janissary corps.