The diplomatic context at Constance included the revolt of the Bohemian Hussites, who looked upon Poland as an ally in their wars against Sigismund, the emperor elect and new king of Bohemia. In 1421, the Bohemian Diet declared Sigismund deposed and formally offered the crown to Władysław on condition that he accept the religious principles of the Four Articles of Prague, which he was not prepared to do. After Władysław's refusal, Vytautas was postulated (elected in absentia) as Bohemian king, but he assured the pope that he opposed the heretics. Between 1422 and 1428, Władysław's nephew, Sigismund Korybut, attempted a regency in war-torn Bohemia, with little success. Vytautas accepted Sigismund's offer of a royal crown in 1429—apparently with Władysław's blessing—but Polish forces intercepted the crown in transit and the coronation was cancelled.