MEMBERS OF THE FIRST OFFICER CANDIDATE SCHOOL (OCS) in the United Kingdom decontaminating a building that has been subjected to mustard gas (top). Machine gun training at OCS (bottom). Qualified enlisted men were selected from units stationed in the British Isles and sent to this school where, upon the successful completion of the courses of instruction, they were commissioned second lieutenants in the Army of the United States. The first class began in September 1942 and there were in all seven classes, each lasting for approximately three months. The OCS in England graduated and commissioned a total of 472 men.] [Illustration] [Illustration: ENGLAND A FIGHTER PILOT, Standing beside his plane in England, wearing an oxygen mask and helmet equipped with earphones. Over his leather flying jacket is a life preserver. A number of young men from the United States joined the Canadian and British air forces before America’s entry in the war. When the U. S. declared war these pilots were transferred to the U. S. air force. The strength of the U. S. air force in 1940 was about 43,000 men and 2,500 planes. In early 1944 there were 2,300,000 men and 80,000 aircraft.] [Illustration: ENGLAND INTERIOR OF A B-17 showing two .50-caliber Browning machine guns. These planes were highly complex machines, well armed, with machine guns in front, rear, sides, top, and bottom. The man in the picture is working on the gun turret which protruded beneath the fuselage. The tank on top of this turret was for oxygen.] [Illustration: ENGLAND AN ORDNANCE SPECIALIST in the repair of optical equipment cleans a pair of field glasses, England, September 1942. Ordnance responsibility extended to “everything that rolls, shoots, is shot, or is dropped from the air.” Its complete catalogue contained 35,000 separate items, ranging from watch springs and firing pins to 20-ton howitzers and 40-ton tanks.] [Illustration: ENGLAND A REPAIRED M 3 MEDIUM TANK is given final check by Ordnance personnel. Every tank, gun, or vehicle, damaged either by an accident or later in combat, which could be repaired meant one less new tank to be supplied. As the war progressed the medium tank underwent changes as did a great deal of other U. S. equipment. It became lower so as to present a more difficult target, the riveted hull was replaced by a welded or cast hull, and toward the end of the war the suspension system was changed. These, and other mechanical changes, with the addition of better armament and armor, made the vehicle a more formidable fighting machine, better able to combat enemy tanks.] [Illustration: ENGLAND