https://en.wikipedia.org/wiki/Battle_of_Kosovo_(1448)

''Scanderbeg intended to go "peronalmente" with an army to assist Hunyadi, but was prevented from doing so by Branković, whose lands he ravaged as punishment for the Serbian desertion of the Christian cause.''


Four years after his defeat at Varna, John Hunyadi, the richest landowner in Hungary joined forces with Albania's war leader Gjergj Skanderbeg in an alliance that also included Serbia and Bosnia.[8][9] Resolved to defeat the Ottoman army Hunyadi raised an army of 24,000 men, including 8,000 Wallachians,[7]