The loyalty of the Ragusans to Hungary was sorely tried this same year, for Sigismund prepared to make war on Tvrtko as a usurper and reinstate Ostoja as the rightful king. They would not side openly with Tvrtko against this suzerain, but they did not wish to lose the valuable and hardly won favours of Bosnia; they therefore placed their arsenals at the disposal of Tvrtko’s agents, who bought large supplies of arms for the war.[348] Sigismund sent three armies into Bosnia—one under the Banus of Mačva by way of Usora, a second under Paul, Banus of Croatia, up the Una valley towards Bihać, and a third to guard the Bosnian-Slavonian frontier under Peter of Perén. Ladislas lent his fleet to Hrvoje to keep watch at Arbe and attack Sigismund’s forces if they should invade the littoral. But after a few ephemeral successes the Hungarians were defeated at all points, and Tvrtko’s position was thereby considerably strengthened. Ostoja, fearing for his life, asked for a safe conduct to Ragusa in April 1407, and the Senate, much to his surprise, granted it, forgiving him all his former hostility, “for any man who from Bosnia or from the land of any other lord takes refuge in our city, according to the law, may enter freely and live here undisturbed.” But after all he did not avail himself of the permit, either because he mistrusted the Ragusans, or because he still hoped to regain his throne. While Tvrtko was trying to win Cattaro and Budua from the Balšas, Sigismund was preparing his revenge, and in 1408 invaded Bosnia with a large army, defeated the usurper and captured him, together with a large number of magnates, of whom 126 were beheaded at Dobor. Ostoja was replaced on the throne, and Sigismund retired to Buda with Tvrtko in his train.