 With his father 's death , Ladislaus inherited an enormous domain in 1456 . The ambitious Ladislaus had his father 's main opponent , Ulrich II , Count of Celje , captured and murdered on 9 November . The King , who promised amnesty to Ladislaus under duress , had him arrested in next year . Ladislaus was sentenced to death for high treason . He was executed on 16 March 1457 . 
