The Battle of Kosovo defined the long-term fate of Serbia, because now it had no force capable of standing up to the Turks directly. This was an unstable period marked by the rule of Prince Lazar's son — despot Stefan Lazarević — a true European-style knight, a military leader, and a poet. Stefan was at first a vassal of Sultan Bayezid I, distinguishing himself at the Battle of Nicopolis in 1396 and at Ankara in 1402, later gaining independence after the loss of Bayezid. His cousin and heir Đurađ Branković moved the capital to the newly built fortified town of Smederevo. The Turks continued their conquest until they finally seized all of northern Serbian territory in 1459 when Smederevo fell into their hands. The only free Serbian territories were parts of Bosnia and Zeta. After the fall of Principality of Zeta in 1496, Serbia was ruled by the Ottoman Empire for almost three centuries. A Serbian principality under Hungarian protection was created, after the fall of the Serbian Despotate, by the Branković family (later other Serbian noblemen assumed the throne) in what is now Vojvodina, Slavonia, and Bosnia. The subordinate state spent its entirety fighting the Ottomans and represented the heritage of what was left of the Serbian Kingdom. It fell in 1540 when the Ottoman conquest of the Serbian lands, which lasted through about 200 years of continuous warfare, was finally complete.