Despite these successes the Ottomans were dealt a major setback when at Ankara in 1402 Timur the Great of the Timurid Empire defeated and captured the Ottoman Sultan Bayezid the Thunderbolt (so named for the speed of his crushing victories against his Christian opponents, most notably at Nicopolis). After a decade of internecine battles, Mehmed I emerged victorious and reestablished the Ottoman Empire and Byzantine Emperor accepted its vassalship and agreed to pay tribute.