Bidspirit auction | Great War WW1 Imperial German

Great War WW1 Imperial German Flying Corp, Lt. Ehrhardt von Teubern who was Max Immelmanns observer during WW1 signed No 27 Squadron Royal Air Force Hans Rossbach cover, the rear of the cover is marked Nr 1 von 25 Exemplaren (certified 1 of 25 so signed) and the cover contains a reproduction WW1 photograph of von Teubern and Immelmann. Was with the legendary Max Immelmann on the mission where he was awarded the Iron Cross. Career info also printed on back of the cover in German. VERY RARE AUTOGRAPH.