Ladislaus V or Ladislaus Posthumus, 1440–57, king of Hungary (1444–57) and, as Ladislaus I, king of Bohemia (1453–57). Ladislaus, duke of Austria by birth as the posthumous son of Albert of Hapsburg, duke of Austria and German king (see Albert II), was recognized (1443) as king of Bohemia by the majority of the Bohemian diet but was only crowned in 1453. He was elected king of Hungary after the death (1444) of Ladislaus III of Poland. However, his guardian and second cousin, Holy Roman Emperor Frederick III, at whose court Ladislaus grew up, refused to surrender the boy and thus enable him to take his rightful place as king of Bohemia and of Hungary. In 1451 the Austrians rebelled and demanded that Frederick release their young duke; he was released in 1452 as the unofficial ward of his powerful uncle, Ulrich, count of Cilli, but Ladislaus governed none of his realms. George of Podebrad was regent in Bohemia, John Hunyadi in Hungary. After the death (1456) of Hunyadi, Ulrich became regent of Hungary. He and the king were captured by Hunyadi's son Ladislaus, and Ulrich was killed. Freed shortly afterward, the king had Ladislaus Hunyadi executed in 1457 and then fled to Prague, where he died, probably by poisoning. He was succeeded in Austria by his Hapsburg relatives, in Bohemia by George of Podebrad, and in Hungary by Matthias Corvinus.