A period of minor operations followed. Perhaps because of Wallenstein's ambiguous conduct, he was assassinated in 1634. Despite Wallenstein's fall, the imperial forces recaptured Regensburg and were victorious in the Battle of Nördlingen (1634). The Swedish army was substantially weakened, and the fear that the power of the Habsburgs would become overwhelming caused France, led by Louis XIII of France and Cardinal Richelieu, to enter the war on the Protestant side. (Louis's father Henry IV of France had once been a Huguenot leader.) In 1635 Ferdinand signed his last important act, the Peace of Prague (1635), yet this did not end the war.