 He was assigned to "Jagdgeschwader" 26 (Fighter Wing 26—JG 26) on the Channel Front which was tasked with intercepting Royal Air Force (RAF) incursions over occupied France and Belgium.He achieved his first aerial victory in August 1941.Bartels was transferred to "Jagdgeschwader" 5 on the Eastern Front where he was awarded the Knight's Cross of the Iron Cross for 46 aerial victories.