Battle of Dunkirk; on 1 June 1940 I. Gruppe claimed three Hurricanes over the port. ZG 1 remained active during Fall Rot, the second phase of the Battle of France. The Luftwaffe had proven successful in the Air interdiction role, but became a victim of its own success when German logistics began to strain because of the infrastructure damage caused by bombing. An effort was made to repair French and Belgian road, bridges and railway lines. Fuel shortages occurred, but I./ZG 1 at Norrent-Fontes, for example, reported of aviation fuel on 7 June just days into the beginning of the second offensive. II./ZG 1 was based at Trier-Euren and both served under Jagdfliegerführer 3. German bomber wings were ordered to attack rail traffic in the Rhône and shipping in Marseille. They overflew Switzerland for convenience and as a mark of arrogance in their perceived superiority. The Swiss Air Force intercepted on one occasion, and with some units equipped with German-built Bf 109s, shot down six He 111s. Göring was furious and ordered missions to continue with Bf 110 escort. The second mission resulted in the destruction of one Swiss fighter. The Nazi leaderships obsession with saving face, resulted in II./ZG 1 being ordered to fly missions over Swiss air space. This cost the unit five Bf 110s, and the commanding officer of 6. Staffel on 8 June. Thereafter, operations over Switzerland were stopped. Battle of Britain and Channel Front The Battle of Britain began in July 1940, but ZG 1 was already being broken up to form new units. On 22 June I./ZG 1 became I./Nachtjagdgeschwader 1, a night fighter wing and returned to Germany. On 26 June 1940 II./ZG 1 was renamed III. Gruppe of Zerstörergeschwader 76 (ZG 76—76th Destroyer Wing). ZG 1 had formally ceased to exist for the next 18 months. I. Gruppe retained its Zerstörer status into July 1940 for it is listed on the Quartermaster of the Luftwaffe as I(Nacht)/ZG 1. Two aircraft belonging to this unit were reported destroyed on 25 July; one in action with an RAF bomber and another in an accident. Two crewmen were killed and two wounded. Eastern Front In June 1941 the Wehrmacht and its Allies began Operation Barbarossa, the invasion of the Soviet Union, initiating the war on the Eastern Front. The failure of Barbarossa and the requirement for heavy fighter groups which could act with versatility in