In its final year as a component of the Signal Corps, from the declaration of war on Germany by the United States in April 1917 to May 1918, the Aviation Section developed into parallel air forces, a training force in the United States and a combat force in Europe. After February 1917, the section consisted of three divisions in the OCSO: Administrative, Engineering, and Aeronautical. At the onset of war the Aviation Section consisted of only 65 regular officers, 66 reserve officers, 1,087 enlisted men, and 280 airplanes (all trainers), with more on order. The service had 36 pilots and 51 student pilots. By comparison, the United States Navy's air service had 48 officers, 230 enlisted men, and 54 powered aircraft.