 John Hunyadi 's rapid advance , which astonished his contemporaries , and gave rise to legends about his origins . According to one of these stories , recorded in detail by the 16th @-@ century historian Gáspár Heltai , John Hunyadi was the illegitimate son of King Sigismund with a woman named Elizabeth , who was the daughter of a " rich boyar " from <unk> in Hunyad County . Antonio Bonfini , on the other hand , wrote that John Hunyadi 's mother was an unnamed Greek woman who was related to the Byzantine Emperors . 
