On 9 April 1944, "Oberleutnant" (First Lieutenant) Lang was appointed "Staffelkapitän" of the 9./JG 54 (9th Squadron of the 54th Fighter Wing) engaged in Defence of the Reich on the Western Front. He became the 448th recipient of the Knight's Cross of the Iron Cross with Oak Leaves () on 11 April 1944 after 144 aerial victories, all claimed on the Eastern Front. The presentation was made by Adolf Hitler at the Berghof, Hitler's residence in the Obersalzberg of the Bavarian Alps, on 5 May 1944. Also present at the ceremony were Anton Hafner, Otto Kittel, Günther Schack, Alfred Grislawski, Erich Rudorffer, Martin Möbus, Wilhelm Herget, Hans-Karl Stepp, Rudolf Schoenert, Günther Radusch, Otto Pollmann and Fritz Breithaupt, who all received the Oak Leaves on this date.