 Five years later, however, Smederevo, Grgur, and Stefan returned to Branković through the Peace of Szeged.Around the beginning of 1449, Branković imprisoned Hungarian regent John Hunyadi in the dungeons of the fortress until he was ransomed by his countrymen.In 1453, Sultan Mehmed II and Isak-bey Arbanazović led another attack on Smederevo as part of a devastating raid on Serbia.