In 1420 Stephen Tvrtko II. reappeared upon the scene, and the next year he was acknowledged. There followed a breathing-space, for the Turkish general Isaac was defeated and killed during an incursion into Hungary, and Mahomet I., involved in strife with Mustapha, had no leisure to repair the disaster. This did not last long, however, for in 1424 the sons of Ostoja endeavored, with Turkish help, to win back their father’s throne, the only result of which was a war ending with the surrender of a portion of Bosnian territory to Murad II. Again, in 1433, when Tvrtko was fighting with the Servian despot, George Branković, he was suddenly called to the south to withstand a Turkish inroad invited by Radivoj, one of the sons of Ostoja, and this was immediately followed by the rising of Sandalj Hranić, the powerful magnate of Herzegovina, who drove Tvrtko to seek refuge with Sigismund. His absence lasted three years, during which the wildest confusion reigned in Bosnia, the Turks being constantly called in to participate with one side or the other.[343] Meanwhile the rise of the Observantine Franciscans was restoring to the Church some of its old missionary fervor, and furnishing it with the necessary self-devoted agents. In spite of the preoccupations arising from the contest between Eugenius IV. and the Council of Basle, an effort was made to win back Bosnia to the faith. If anything could accomplish this there might be hope from the fierce and inexhaustible enthusiasm of the Observantine Friar, the Blessed Giacomo della Marca, who had already given evidence of ruthless efficiency as inquisitor of the Italian Fraticelli. In 1432 he was accordingly sent with full powers to reform the Franciscan Order in Slavonia, and to turn its whole energies to missionary work. Under this impulsion we are told that conversions were numerous from Bosnia to Wallachia, and Eugenius IV. stimulated rivalry by also setting the Dominicans at work. In 1434 Giacomo was driven out, but was sent back the next year, and distinguished himself by redoubled ardor and success, attributed, according to his biographers, partly to his miraculous powers. Alarmed at his progress, the wicked queen sent four assassins to despatch him, when he extended his arms and bade them do whatever God would permit, whereupon they became rigid and suffered agonies until he prayed for their release. Indignant at this attempt, he bearded the king and queen in full court, and his boldness gained him so many converts that the king became alarmed for his throne. A sorcerer was accordingly employed to slay the intrepid inquisitor, but Giacomo promptly rendered the man speechless for life. Some heretics then sawed through the supports of a platform where he was preaching. It fell, but he escaped, and to this day, says the legend, the posterity of the perpetrators have all been born halt and lame. These proofs of divine favor led to numerous conversions, but he became involved in quarrels with the Catholic