Hunyadi departed for the new campaign at the head of an army of 16,000 soldiers in September 1448. About 8,000 soldiers from Wallachia also joined his campaign. For Đurađ Branković refused to assist the crusaders, Hunyadi treated him as the Ottoman's ally and his army marched through Serbia plundering the countryside. In order to prevent the unification of the armies of Hunyadi and Skanderbeg, Sultan Murad II joined battle with Hunyadi on Kosovo Polje on 17 October. The battle, which lasted for three days, ended with the crusaders' catastrophic defeat. Around 17,000 Hungarian and Wallachian soldiers were killed or captured and Hunyadi could hardly escape from the battlefield. On his way home, Hunyadi was captured by Đurađ Branković who kept him prisoner in the fort of Smederevo. The Despot was initially contemplating to surrender Hunyadi to the Ottomans. However, the Hungarian barons and prelates who assembled at Szeged persuaded him to make peace with Hunyadi. According to the treaty, Hunyadi was obliged to pay a ransom of 100,000 gold florins and to return all the domains that he had acquired from Đurađ Branković. Hunyadi's oldest son, Ladislaus was sent to the Despot as a hostage. Hunyadi was released, and he returned to Hungary in late December 1448.