The conditions of Venice in the middle of the fourteenth century were far from prosperous. The plague of 1348 had carried off three-fifths of the population, in spite of the most stringent precautions.[177] In 1350 the fratricidal war with Genoa was again renewed in consequence of disputes about the Black Sea trade. The battle of the Bosporus (1353) was indecisive; in that of Cagliari the Venetians were successful, but dared not attack Genoa, because the city had placed itself under the protection of the Visconti. But in the same year they were totally defeated at Sapienza in the Greek Archipelago and their whole fleet captured. In 1354 the conspiracy of Marin Faliero broke out, and kept the whole State in a turmoil for many months, until the execution of the Doge and his accomplices.[178] His successor, Giovanni Gradenigo, made peace with Genoa, and the Venetians set to work to rebuild their fleet and restore their exhausted treasury by means of new commercial enterprises in the Levant. But their possession of Dalmatia and the land frontier north of Treviso were now threatened by Lewis of Hungary. The latter allied himself with the Count of Gorizia and the Carraresi of Padua against Venice, and invaded the Trevisan march, defeating all the forces sent against him and capturing city after city. A five months’ truce was concluded in 1356, but when it expired hostilities broke out once more, and the treasury was soon empty. Merchandise might arrive by sea, but with the mainland in the hands of the enemy there was no outlet for its distribution.[179] New taxes were raised, causing much discontent, and the Republic was at last forced to sue for peace. Lewis made the cession of Dalmatia an express condition of his retirement from the Trevisan march. After much discussion and expostulation the Senate was forced to agree to these humiliating terms, and Dalmatia, which had been acquired and maintained at such great sacrifices, was now given up (Feb. 1358). The Republic had hoped to create a diversion by an alliance with the King of Servia, who had been fighting with the Banus of Bosnia, then a Hungarian vassal. But Stephen Dušan got more and more involved in the Greek war, and when the Hungarians invaded the Venetian _terraferma_ he was marching towards Constantinople, but died on the way thither (1355).