A decisive confrontation in the period of the later crusades between the huge armies of the Ottoman sultan Bayezid I and the Mongol ruler of central Asia, Timur Lenk (Tamerlane), who eventually carried the day, thus putting a temporary halt to the expanding Ottoman sultanate and indirectly giving the beleaguered Byzantine Empire breathing space for another half century.
The battle was hotly contested in the plain of the river Chubuk (Turk. Çubuk-ovasi) north of Ankara on 28 July 1402. From its defensive hilly position, the heterogeneous Ottoman army sustained a fierce attack by the Mongol cavalry and was eventually overrun on account of the defection of its Turcoman vassals (whose emirs took Timur’s side) and despite the heroic defense of Bayezid’s Christian vassals, particularly the Serbs who held the sultan’s left flank. Timur, reputedly in a secret plot with the Byzantine regent John VII Palaiologos, seized Bayezid (who was to die in captivity in 1403) and one of his sons, Musa Çelebi; he then captured the town of Brusa, along with Bayezid’s treasures, and consequently shattered Ottoman domination over much of northwestern and southern Anatolia, reestablishing several of the Turcoman emirates (beyliks), while a fierce civil war began among Bayezid’s sons (1402/1403-1413).