After the death of Elizabeth, who was willing to make peace with Władysław, Jiskra remained on the hereditary king's side and made a pact with the occupied cities to secure Ladislaus' rule. In order to make peace Jiskra was invited by Władysław to the Diet of April 1444 along with other supporters of Ladislaus. At the diet he defended Ladislaus' cause with such vehemency, that his violent behavior almost caused his death. Władysław gallantly saved his life when he helped escape the disguised Jiskra to Győr, from where he went to Vienna to the court of
Frederick III, Holy Roman Emperor, to visit Ladislaus. He was elected a High Captain of Upper Hungary in 1445 for his part in the making of a Polish-Hungarian truce after the death of Władysław. He kept this title after the office itself abolished in the next year. Meanwhile, his Czech mercenaries, who called themselves "the Brotherhood," were not obeying Jiskra's orders and were marauding in
Szepes County and
Sáros County and forcing
Catholic priests to perform
Hussite rituals. The Diet of 1449 decided that these Czechs should be attacked. After some unsuccessful minor skirmishes, the Regent,
John Hunyadi, himself marched into battle against Jiskra. The result of his campaign was a truce at
Mezőkövesd in March 1450. Kassa, Lőcse, Eperjes, Bártfa, Körmöcbánya, Selmecbánya and Zólyom remained in Jiskra possession and several smaller Czech bands left the country. Despite the truce Jiskra refused to recognize the authority of the Regent and continued to mint money and award privileges. He called other Hussite bands to the country and fortified a monastery at Losonc (
Lučenec) and marauded the countryside from there. He defeated Hunyadi and conquered most of Upper Hungary with the notable exception of
Eger. He was defeated again after Hunyadi renewed his campaign against him and forced to take an oath of allegiance to the crown. He was convicted again when he did not attend the Diet of 1452. His properties were confiscated. Kassa, Lőcse and Bártfa was given to
Ulrich II, Count of Celje. Shortly after Jiskra left Hungary. ==Against the Hunyadis and in the service of Matthias==