John Hunyadi was a leading Hungarian military and political figure in Central and Southeastern Europe during the 15th century. According to most contemporary sources, he was the member of a noble family of Wallachian ancestry. He mastered his military skills on the southern borderlands of the Kingdom of Hungary that were exposed to Ottoman attacks. Appointed voivode of Transylvania and head of a number of southern counties, he assumed responsibility for the defense of the frontiers in 1441.

He employed professional soldiers, but also mobilized local peasantry against invaders. These innovations contributed to his earliest successes against the Ottoman troops who were plundering the southern marches in the early 1440s. Although defeated in the battle of Varna in 1444 and in the second battle of Kosovo in 1448, his successful "Long Campaign" across the Balkan Mountains in 1443–44 and defence of Belgrade (Nándorfehérvár) in 1456, against troops led personally by the sultan, established his reputation as a great general. 

John Hunyadi was also an eminent statesman. He actively took part in the civil war between the partisans of Wladislas I and the minor Ladislaus V, two claimants to the throne of Hungary in the early 1440s, on behalf of the former. The Diet of Hungary elected Hunyadi as sole regent with the title of governor. Hunyadi's victories over the Turks prevented them from invading the Kingdom of Hungary for more than 60 years. His fame was a decisive factor in the election of his son, Matthias Corvinus, as king by the Diet of 1457. Hunyadi is a popular historical figure among Hungarians, Romanians, Serbs, Bulgarians and other nations of the region.