Despite defeating his brother and rival for the Ottoman throne, Musa, at the Battle of Kosmidion in June 1410, Süleyman's popularity waned. So much so, that when Musa returned to avenge his defeat during the following year, Süleyman's supporters defected to Musa.[3] Süleyman was captured while attempting to escape to Byzantine territories, and was killed by villagers on February 18, 1411.