Stracimir, jealous because Sisman seemed to have received the lion’s share of Alexander’s inheritance, did not hesitate to make overtures to Murad, offering to co-operate with the Osmanlis against his brother and to share the portion of Sisman with them.[312] Before any agreement could be made, however, Stracimir found himself face to face with a terrible danger in the west, which soon caused him to forget both Sisman and Murad. Louis of Hungary had interpreted his crusader’s commission as an authorization to ‘make war against the heretics’. It was a pretext to get possession of Widin, which was essential to his ambitious project of adding Serbia to his kingdom. He attacked the Bulgarians on the ground that they were enemies of the Church and must be forced to acknowledge the supremacy of Rome. Widin was captured and Stracimir imprisoned.[313] Stracimir’s dominions were flooded with Franciscan missionaries, who were backed by a brutal soldiery in their proselytizing efforts.[314] Two hundred thousand Bulgarians abjured the orthodox heresy, and were re-baptized in the Latin rite. This forcible conversion, which was purely a political matter, was as objectionable to the Bulgarians as to the Cretans. They hated ‘with a perfect hatred’ the Franciscans whom Pope Urban had sent, and the cause for which they stood. At the first opportunity, the Bulgarians of the west called in Sisman and Vadislav of Wallachia. The Hungarians were driven out of Widin and the Franciscans in the city massacred.[315] Louis was powerful enough to wreak terrible vengeance. In 1370, Widin fell once more into his hands. The Bulgarians of the western Balkans were subjected to such a relentless persecution that they welcomed the Moslem conquest to secure freedom of worship. Urban had incited Louis to this war, and had congratulated him upon his laudable zeal in converting the heretics.[316] We have already spoken of the punishment that came to Sisman as a result of the detention of John Palaeologos. The Italian crusaders on the Black Sea coast were as powerful an aid to Murad’s empire-building as were the Hungarian crusaders on the western frontier. The successors of Louis reaped the bitter fruits of his insane policy. Louis and Amadeo of Savoy contributed in no little measure to make possible the conquests of Murad. When Amadeo withdrew from Bulgaria, he left the cities he had captured to the Greeks. Sisman was compelled to expend his energy in recapturing them. But Murad had already anticipated him in the important fortress of Sozopolis, which commanded the entrance to the port of Burgas.[317] Shortly after the Ottoman occupation of Sozopolis, the Bulgarians were everywhere dispossessed in Thrace, and the capture of Yamboli[318] forced Sisman to follow the example of John Palaeologos. He became a vassal of Murad. His sister Mara entered Murad’s harem, but with the stipulation that she be allowed to retain her Christian faith.