[1][2] Anselm Casimir Wambold von Umstadt was invited as Imperial Chancellor (Reichserzkanzler) and Bishop-Elector of Mainz.
He also needed to deal with the imminent Swedish threat - on 6 July, shortly after the Diet had opened, Gustavus Adolphus of Sweden had landed in Pomerania Maximilian I of Bavaria feared the rising power of the empire and the strength of Wallenstein's Imperial Army.
The Catholic electors therefore opposed rather than supported Ferdinand, requiring that the imperial army be downsized, the war-taxes reduced and Wallenstein dismissed from command.
Wallenstein was dismissed and Johann Tserclaes, Count of Tilly put in supreme command of imperial forces, which were shrunk despite the Swedish threat.
The Electors blocked Ferdinand the Younger's election as King of the Romans and in the name of their own freedom revoked the Edict of Restitution.