Ferdinand von Spanien
Sweden and the Heilbronn League quickly removed their garrisons in the Rhineland after the battle and handed to France the cities of Colmar, Schlestadt and Basel. The Elector of Saxony opened talks with Ferdinand II, but the Landgrave of Hesse-Kassel and the Duke of Lüneburg still fielded troops against the Emperor and were in the surroundings of Frankfurt am Main. Meanwhile, the Imperial armies were between the rivers Neckar and Main, where they took Heilbronn on 27 September, the same day that the battle of Willstätt was fought. Since the battle of Nördlingen, the Catholics had expelled the Swedish and their German allies from Bavaria, Swabia –except from Ulm and Augsburg, where they still held out but blockaded by the Duke of Bavaria–, Württemberg, and most of Franconia; in words of Diego Aedo y Gallart, secretary of the Cardinal-Infante Ferdinand of Austria: "expelling him [the Swedish] from the roots of the Alps".