In 1633, Sweden and a number of German Protestant states formed the Heilbronn League, which suffered a serious defeat at Nördlingen in September 1634. This crisis moved Richelieu closer to direct intervention in the Thirty Years War; in October, French garrisons occupied towns in Alsace on the left bank of the Rhine, then part of the Empire. Richelieu also proposed replacing Bärwalde with the Treaty of Paris, an agreement between France and the Heilbronn League.