The German invasion of Poland in September 1939 began World War II in Europe. The French Air Force and RAF Bomber Command began bombing raids on German ports and shipping. The Battle of the Heligoland Bight in December 1939 ended Royal Air Force (RAF) daylight operations until 1944. Bomber Command persisted in night operations against Germany, which extended to German towns and cities from 10/11 May 1940. The capitulation of the French after the Battle of France did not end the threat posed by British air power. Wolfgang Falck commanded I/ZG 1 during the German invasion of Denmark. Immediately after the occupation, Bomber Command appeared frequently to attack German positions, and Falck was able to fly interceptions during dusk. Falck was sure that a Messerschmitt Bf 110 unit could defend the airspace at night with assistance from radar operators. Falck was invited to the RLM to express his views to Albert Kesselring, Ernst Udet and Erhard Milch. Hermann Göring, commander-in-chief of the Luftwaffe, ordered Falck to create a "Nachtjagdgeschwader" at Düsseldorf on 22 June 1940.