In 1806 Müffling served under Hohenlohe, Karl August, Grand Duke of Saxe-Weimar-Eisenach, and Blücher, and was included in the capitulation of the latter's corps at Ratekau on 7 November 1806, the day after the Battle of Lübeck. After this he entered the civil service of the Duke of Weimar. He rejoined the army on the outbreak of the German Campaign of 1813, and was placed on the headquarters staff of the Army of Silesia.