 In 1549, he agreed to support Ferdinand's claim, and Imperial armies marched into Transylvania.In the Treaty of Weissenburg (1551), Isabella agreed on behalf of John II Sigismund to abdicate as King of Hungary and to hand over the royal crown and regalia.Thus Royal Hungary and Transylvania went to Ferdinand, who agreed to recognise John II Sigismund as vassal Prince of Transylvania and betrothed one of his daughters to him.