 Complete the following phrase:  After the defeat of the Serbs and Bosniaks in the Battle of Kosovo on 15 June 1389, Ivan Shishman had to seek help from Hungary. During the winter of 13911392, he entered into secret negotiations with the King of Hungary Sigismund, who was planning a campaign against the Turks. The new Ottoman sultan Bayezid I pretended to have peaceful intentions in order to cut off Ivan Shishman from his alliance with the Hungarians. However, in the spring of 1393 Bayezid gathered a large army from his dominions in the Balkans and Asia Minor and attacked Bulgaria. The Ottomans marched to the capital Tarnovo and besieged it. The defence of the capital was led by Patriarch Evtimiy because Ivan Shishman was located in Nikopol, presumably for better communication with Sigismund. After a three-month siege, 