The battle of Kóssovo was the turning-point in Tvartko’s fortunes. His intrigues in Croatia, and a victory obtained over the Hungarian arms in Dalmatia, roused the Magyar King, Sigismund, to vengeance, and Tvartko, prevented himself by bodily weakness from taking an active part in the hostilities, saw his allies defeated, his province of Ussora overrun,[88] and himself reduced to renew his homage. In 1391 Tvartko dies, of vexation, it is said, at these reverses, and is succeeded by Stephen Dabiscia, otherwise known as Tvartko II., and he again in 1396 by Tvartko III.[89] The greater part of the long reign of this King, which lasted forty-seven years, is distracted by perpetual wars, connected with the disputed succession of the Hungarian crown. It is extremely difficult to trace out the aims of the different parties who are now disputing for mastery in Bosnia. At one time Tvartko III., who seems, like his father, Tvartko I., to have aimed at Croatian annexations, appears at the head of an insurrection of Bosnian and Croatian magnates against Sigismund of Hungary, and in 1408 is defeated and captured under the walls of his historic Castle of Doboj,[90] where the conqueror executed 180 Bosnian and Croatian nobles. Tvartko, though forced to resume his allegiance, was suffered to retain his crown, and for many years we find him maintaining his position in league with the party of Sigismund among the Magyars, and generally by the support of the Bogomiles, and the popular party who seem to be identical with them. When the Magnates and their auxiliaries of the Neapolitan and Dalmatian faction sought to oppose him and set up a rival king, Tvartko carried out his national policy still further by sending a message to Vladislaus Jagellon, the Polish claimant of the Hungarian throne, in which he offered him his homage and begged for assistance on the plea of the common origin of the Poles and Bosniacs.[91]