On 1 March 1940, Ludwiger was appointed commander of the 83rd Infantry Regiment of the 28th Infantry Division, with which he took part in the Invasion of France. Following Operation Barbarossa, he was awarded the Knight's Cross of the Iron Cross on 15 July 1941, and was promoted to "Oberst" on 1 September 1941. Due to the heavy casualties his regiment (and the division as a whole) suffered while fighting in the Battle of Moscow, the 28th Infantry Division was moved to occupied France to refit as a "Jäger" division on 1 December. The 28th Jäger Division was sent back to the front in southern Ukraine, where it participated in the Battle of the Kerch Peninsula in the Crimea and in the Strait of Kerch. During his award ceremony, he met his future superior, Hubert Lanz, and his future subordinate Harald von Hirschfeld.