The Ragusan Senate had the foresight to understand the growing importance of the Ottoman Turks, and having obtained from Urban V. an exemption to trade with the Infidel, it contracted commercial agreements with the Sultans of Egypt, Syria, and Konia in 1359, and in 1365 obtained from the Sultan Murad a firman granting the citizens of Ragusa freedom to trade in all parts of the Ottoman dominions and protection for their commercial factories, in exchange for a yearly tribute of 500 ducats. Ragusa was thus the first Christian State to make a treaty with the Ottoman Turks, and its citizens were enabled to penetrate into the remotest parts of the Turkish Empire and form permanent settlements there at a time when other Christians were either excluded altogether or limited to a few coast towns. The tribute which they paid for these advantages, although often raised subsequently, proved a most profitable investment. In 1378, in consequence of the intrigues of Venice and Genoa to obtain a predominant position at Constantinople, war broke out between the two Republics—the famous Chioggia war—in which Ragusa too was involved. The Genoese induced Francesco Carrara, lord of Padua, who had been humbled but not subdued by Venice, to join them, and further help was obtained from Louis of Hungary. Ragusa, as vassal of that potentate, joined the coalition. But Venice, undismayed, made all preparations for war, and invested Vettor Pisani with the supreme command at sea. A Venetian victory off Cape Antium was won on May 30, and Pisani took Sebenico and Cattaro by storm; these and other towns on the Adriatic coast which his garrisons occupied were harried and blockaded by Ragusan vessels, who also seized this opportunity to destroy the salt-pans of Cattaro, thus ridding the Republic of a dangerous competitor.[310] The Ragusans were in great fear of an attack by the Venetian fleet, and made desperate efforts to strengthen the defences of the town and of Stagno. They also asked for assistance from Tvrtko, King of Bosnia, who offered them a contingent; but on hearing that he was treating with the Venetians, possibly with a view to a move against Ragusa, they refused it. On October 14, 1378, the Genoese fleet under Fieschi put in at Ragusa,[311] where a Ragusan galley joined it, and the admiral received two bombards and a present of money from the Republic. Armed barques issued forth from the town to scour the Adriatic and obtain news of the movements of the Venetian fleet, which were at once transmitted to the Banus of Dalmatia and Croatia at Zara, while privateers cruised about to plunder the enemy’s merchantmen. Ragusan ships were, in fact, the eyes of the allied fleet.