Stefan Uroš V and Venice. Neither provided much help as Venice was concerned that only their warships were on the Adriatic. In fact, Venice wrote to Uroš V in 1368, complaining that Serbia's armed ships were on the Adriatic, citing Bar, Budva nand Ulcinj to have them. They had also stated that this was also a violation of the Venetian-Serbian treaty and threatened to treat the ships as pirate vessels. However, Uroš V replied to that letter, stating that those ships that Venice were complaining about belonged to Đurađ I Balšić, the lord of Zeta. Uroš was unhappy with Đurađ's actions as they were directed against Kotor, which was under Uroš V's suzerainty. Concluding that Đurađ was a rebel, the Serbian court claimed no responsibility for Đurađ's actions that might violate the Venetian-Serbian treaty. In 1369, Đurađ laid siege to Kotor, which, having no choice, turned to the Kingdom of Hungary for support and sought for Hungarian suzerainty. Hungary sent a nobleman from Zadar to hold Kotor. This action only increased Kotor's troubles, as it lost its trade privileges with Serbia for a time, causing a larger economic turmoil for Kotor. By spring 1370, probably through Venetian mediation, Đurađ had made peace with Kotor. However, in the same year, Nikola Altomanović attacked Kotor. In 1371, Đurađ announced to the Republic of Ragusa that he, Vukašin Mrnjavčević and his son, Marko, along with their armies, were in Scutari, preparing an attack on Nikola Altomanović. Ragusa assisted their campaign by providing ships to transport men and supplies, since their campaign was in Ragusa's interest. However, the campaign never took place as Vukašin and Marko went to aid Vukašin's brother, Jovan Uglješa, in a campaign against the Turks, which ended up in total disaster, Vukašin and Uglješa and their army being wiped out in the Battle of Maritsa. Serbian Prince Lazar Hrebeljanović and Bosnian Ban Tvrtko I allied themselves to defeat Nikola Altomanović. Desperate for a strong ally, Altomanović began negotiations with Đurađ. Most historians agree that in concluding negotiations, Đurađ gained the towns of Trebinje, Konavle and Dračevica (Herceg Novi) from Altomanović, possibly a bribe to remain neutral within the war. Other historians, however, follow Mavro Orbini's account and argue that Đurađ never concluded such an agreement, rather conquered the towns he gained from the agreement himself after Altomanović was defeated in 1373. On 30 November 1373 the Balšić brothers issued an