in his head. Algirdas, Grand Duke of Lithuania, hired Tatar mercenaries who stormed into Podolia, Louis returned to Hungary because he feared a Tatar invasion of Transylvania. Pope Clement proclaimed a crusade against the Lithuanians and the Tatars in May, authorizing Louis to collect a tithe from Church revenues during the next four years. The pope stated that he had never "granted a tenth of such duration", emphasizing the link between his magnanimity and the release of the imprisoned Neapolitan princes. The pope also authorized Louis to seize the pagans' and schismatics' lands bordering on his kingdom. Although Louis signed an alliance with the Republic of Genoa in October 1352, he did not intervene in the Genoese–Venetian War, because his truce of 1349 with Venice was still in force. Louis married Elizabeth of Bosnia, who was the daughter of his vassal, Stephen II, in 1353. Historian Gyula Kristó says that this marriage showed Louis's renewed interest in the affairs of the Balkan Peninsula. While he was hunting in Zólyom County (now in Slovakia) in late November 1353, a brown bear attacked him, inflicting 24 wounds on his legs. Louis's life was saved by a knight of the court, John Besenyő, who killed the beast with his sword. According to Matteo Villani, Louis launched an expedition against the Golden Horde at the head of an army of 200,000 horsemen in April 1354. The young Tatar ruler, whom historian Iván Bertényi identified as Jani Beg, did not want to wage war against Hungary and agreed to sign a peace treaty. Although no other primary source mentioned that campaign and treaty, the Tatars made no plundering raids in Transylvania after 1354, which suggests that Villani's report is reliable. In the same year, Louis invaded Serbia, forcing Stefan Dušan to withdraw from the region along the river Sava. Under duress, Dušan initiated negotiations with the Holy See for acknowledgement of the popes' primacy. The following year, Louis sent reinforcements to Casimir III to fight against the Lithuanians, and Hungarian troops supported Albert II, Duke of Austria, against Zürich. The Venetian delegates offered Louis 6–7,000 golden ducats as a compensation for Dalmatia, but Louis refused to give up his plan to reconquer the province. He signed an alliance with Albert II of Austria and Nicolaus of Luxemburg, Patriarch of Aquileia, against Venice. Upon his order, Croatian lords besieged and captured Klis, a Dalmatian fortress that