Timour plundered Siwas and moved into Western Anatolia and Syria. Bayezid gathered his forces and attacked Angora in 1402. However, he was routed by Timour and taken prisoner and died in captivity in 1403.
On Bayezid's death, his sons declared separate, independent sultanates - Solyman in Romelia, Isa Chelebi in Balikeseer, Chelebi Mehmed in Amassia and Mousa Chelebi in Brusa.
Subsequently, Chelebi Mehmed became the sole sovereign in 1413. After his death in 1421 his son Amurath the Second took his place.
He supressed a rebellion led by his brother Moustapha, attacked the Byzantines, made war with Venice and besieged Eghriboz and Morea. In 1430 he regained Salonica from the Venetians and Wallachia and Serbia joined the Ottoman Empire once more. In 1437 Hamidili, Tashili, Koniah and Beysheheer were conquered.
Amurath left the throne to his young son Mehmed but this resulted in new attacks by the Crusaders. However, the invaders were routed and Amurath took the throne once more. He defeated another Crusader force in 1448 and then attacked Albania. Akcha-Hissar was besieged but not taken.
On Amurath's death, his son Mehmed succeeded him. Having built the fortress of Roumelia he then besieged Istanbul. After a siege of 53 days the city fell on May 29th, 1453.