The Holy Roman Emperor, with his Saxon and Roman Catholic allies, was fighting for the control of northern Germany against the Swedes and an alliance of Protestant princes opposed to Habsburg hegemony. The Imperial army was larger in strength than the Swedish army, but at least one-third of it was composed of Saxon units of questionable quality. The Swedish artillery was considerably stronger, leading the Imperial commanders to maintain a largely defensive position on the hill tops. A Swedish-allied army commanded jointly by Johan Banér and Alexander Leslie, later 1st Earl of Leven decisively defeated a combined Imperial-Saxon army, led by Count Melchior von Hatzfeld and the Saxon Elector John George I.