But Venice had to pay more than one heavy penalty for her success. In the east the war of the two republics had been [Sidenote: Venice after the War.] suicidal. In their mutual jealousy they had completely lost sight of their common interest in upholding the Eastern Empire against the Turks. The struggle between Venice and Genoa was among the chief causes of the rapid growth of the Ottoman power, which was destined to be fatal to both the contending states. The more Venice gained in the east by the decline of Genoa the more she stood to lose to the advancing Turks; and nearer home the struggle was costly to Venice. By the peace of Turin, in 1381, she had to confirm the cession of Dalmatia to Hungary, to resign the island of Tenedos, which had been the occasion of the war, and to give up Treviso and all other possessions on the mainland of Italy. All that she had gained in the contest with the Scaligers was lost again. It is true that Treviso was ceded to Leopold of Hapsburg in order to disappoint Francesco Carrara, whose aggrandisement would be much more dangerous to Venice. But Leopold had too much to engage his attention in Germany to be keenly interested in Italian territories. Five years later he sold Treviso, with Feltre and Ceneda, to Carrara, who thus obtained that control over the approaches to the Alpine passes which had driven Venice to make war on Mastino della Scala. For the second time Venice was forced by the same danger to take an active part in the politics of northern Italy. There was one obvious method of humbling the house of Carrara, and that was to invite the intervention of Gian Galeazzo Visconti, who required the annexation of Padua to complete his supremacy in Lombardy. On the other hand, such a policy involved the equally obvious danger that the lord of Milan would prove a far more formidable neighbour than the lord of Padua. To understand the course of action adopted by Venice in this dilemma it is necessary to turn to the history of Milan.