The Northern Bombing Group consisted of United States Navy and United States Marine Corps squadrons conducting strategic bombing of German U-boat bases along the Belgian coast during World War I. The first United States military unit sent to Continental Europe (France)[1] was the First Aeronautic Detachment of seven naval officers and 122 enlisted men who arrived in France on 5 June 1917. These men became the nucleus of the United States naval aviation forces in Europe. They formulated a strategic bombing plan approved by the Secretary of the Navy on 30 April 1918, but chronic difficulties in obtaining aircraft prevented establishment of an effective bombing campaign before the war ended six months later.[2]