You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
He is the hero of my TL Isabella! - Casmir IV the Catholic his OTL equivalent is Sigismund of Luxembourg - he is not the son of Charles IV but rather the son of Wladyslaw Opolczyk with Elisabeth I of Poland who in OTL became the wife of Charles IV.