MEDIUM M3 TANKS in an Ordnance Depot, England (top). Combat tracked vehicles temporarily stored before being issued to the using units (bottom). After a vehicle arrived in the United Kingdom there was much to be done before it could be issued to the using unit. Tanks were received from the United States with about 500 items of accessory equipment, including small arms, radio, tools, gun sights, and other incidentals, packed in waterproofed containers; many were coated with a rust-preventive compound. The job of preparing an M 4 tank took approximately fifty working hours. Accessories were unpacked, cleaned, tested, and installed; the motor and all mechanical components were checked and tuned. When a vehicle left the Ordnance depot it was completely supplied, including ammunition and rations.] [Illustration] [Illustration: ENGLAND A 105-MM. HOWITZER MOTOR CARRIAGE M 7 on maneuvers in England, March 1943. This was an open-top, lightly armored vehicle and was the principal artillery weapon of an armored division.] [Illustration: NORTH ATLANTIC U. S. NAVY PLANE attacks and sinks a German submarine in the North Atlantic, June 1943. The sinking of a British liner without warning by a German submarine off the coast of Scotland on 3 September 1939 opened the battle of the Atlantic, which continued until 14 May 1945 when the last U-boats surrendered at American Atlantic ports. Enemy submarines, traveling alone or in wolf packs, sank many Allied ships but by the middle of 1943 the menace had been reduced to a problem. This was accomplished by the use of the interlocking convoy system that provided escort protection along the important convoy routes, small escort aircraft carriers and destroyer escorts, and planes, from which hunter-killer groups were formed to seek out and destroy the U-boats.] [Illustration] [Illustration: SCOTLAND LIGHTERS PULL ALONGSIDE THE QUEEN ELIZABETH to unload U. S. troops in Scotland (top). Representatives of the American Red Cross serving refreshments to Waacs who have just arrived in Scotland (bottom). On one trip the Queen Elizabeth carried a record load of 15,028 troops. Between December 1941 and June 1944 the Queen Mary and the Queen Elizabeth transported a large portion of the total number of troops to the United Kingdom, running alone through seas in which their great speed was their chief protection against enemy submarines.] [Illustration] [Illustration: GERMANY