SOLDIERS LAND FROM AN ASSAULT BOAT during a training exercise in Scotland, July 1942. The base of fire of a rifle platoon was its automatic weapons. The riflemen concentrated their fire on the impact area blocked out by the automatic weapons. The base of fire of a U. S. rifle squad in World War II was the Browning automatic rifle (BA R). The man in right foreground is armed with this weapon. The two men behind the soldier with the BA R are armed with .30-caliber U. S. rifles M 1.] [Illustration: GERMANY TWO TYPES OF U. S. HEAVY, FOUR-ENGINED BOMBERS. Consolidated B-24 Liberators on a bombing mission over Europe (top); Boeing B-17 Flying Fortresses dropping bombs on enemy installations in Bremen, Germany, while flak bursts around them (bottom). The first U. S. air unit to engage in combat over Europe was a light bombardment squadron. Flying British planes, six U. S. crews joined six RAF crews in a daylight attack against four airdromes in the Netherlands on 4 July 1942. On 17 August twelve B-17’s, accompanied by four RAF Spitfire fighter squadrons, attacked the marshalling yards at Rouen, France, and successfully completed the first U. S. attack over Europe. From these small beginnings the number of planes taking part in the raids grew until the average per raid in 1943 was 570 heavy bombers, a figure that was to be almost doubled in 1944.] [Illustration] [Illustration: ENGLAND THREE TYPES OF ESCORT FIGHTER PLANES over England. From top to bottom: Lockheed P-38 Lightning, North American P-51 Mustang, Republic P-47 Thunderbolt. P-47’s were the first to join the British Spitfires in providing escort for heavy bombers, the P-38 was available in small numbers in October 1943, and the P-51 began to appear in January 1944. At first the 47’s flew top cover, but before long they began to drop down and engage the enemy fighter planes. As the war progressed the escort opened out more and more until it became a huge net to envelop the enemy.] [Illustration: ENGLAND A BRITISH POLICE SERGEANT gives road direction to a U. S. first sergeant during a march. By the end of June 1944 there was a total of 140,656 Negro personnel in the European Theater of Operations assigned to both combat and service units. The M 1 helmet worn by the sergeant was standardized on 9 June 1941, and mass production began shortly thereafter, it replaced the earlier M 1917A 1 helmet shown in preceding pictures.] [Illustration: ENGLAND