After Sweden had to acknowledge her first serious defeat in the Battle of Nördlingen (1634), Ferdinand II, Holy Roman Emperor and several Protestant states concluded the Peace of Prague in May 1635. Calvinist Brandenburg was reluctant to sign, since besides the announced annulment of the Edict of Restitution, toleration of Calvinism was not mentioned. To get Brandenburg to sign up, Sweden and Ferdinand promised her the succession in the Duchy of Pomerania in return.