The Ottoman Interregnum (also known as the Ottoman Triumvirate; Fetret Devri in Turkish) was a period in the beginning of the 15th century when chaos reigned in the Ottoman Empire following the defeat of Sultan Beyazid I in 1402 by the Mongol warlord Tamerlane.

Around 1410 the three sons of Beyazid left alive after the Battle of Ankara ruled each half of the remaindants of the empire. The eldest son, Suleiman Çelebi, ruled northern Greece, Bulgaria and Thrace. His brother, İsa Çelebi ruled Greece and the westernmost of Anatolia, however he was overthrown by the younger half-brother Mehmed Çelebi from his capital in Bursa in 1404. Suleiman then acquired southern Greece as well and Mehmet ruled over Anatolia. Mehmet sent his younger brother Mûsa across the Black Sea with a large army to conquer Suleiman. Mûsa won in Bulgaria in 1410 and Suleiman was forced to retreat south to Greece.

Mûsa then proclaimed himself as sultan of the Ottoman Empire. Mehmed became furious and sent a small army over to Gallipoli where it was defeated. Mehmed later came to his senses and forced an alliance with the Byzantine Empire. Three years later Mehmed sent over a new army that defeated Mûsa in Kamerlu, Serbia. It was then easy for Mehmed I to overthrow his last brother in Greece and become the Ottoman sultan.