John Hunyadi died on 11 August 1456, less than three weeks after his greatest victory over the Ottomans in Belgrade. John's elder sonMatthias's brotherLadislaus became the head of the House of Hunyadi. John's conflict with Ulrich II, Count of Celje ended with Ulrich's capture and assassination on 9 November. Under duress, King Ladislaus the Posthumous promised he would never take his revenge against the Hunyadis for Ulrich's killing. However, the murder turned most baronsincluding Palatine Ladislaus Garai, Judge royal Ladislaus Pálóci, and Nicholas Újlaki, Voivode of Transylvaniaagainst Ladislaus Hunyadi. Taking advantage of their resentment, the King had the Hunyadi brothers imprisoned in Buda on 14 March 1457. The royal council condemned them to death for high treason and Ladislaus Hunyadi was beheaded on 16 March.