[Illustration] [Illustration: ENGLAND 155-MM. GUNS AND 105-MM. HOWITZERS (top and bottom respectively) stored in England, 1944. After about 2,250 rounds had been fired, the barrel of the 155-mm. gun had to be replaced; in howitzers the number of rounds was higher.] [Illustration] [Illustration: ENGLAND DIESEL LOCOMOTIVES, TANK CARS, AND FREIGHT CARS lined up in England to be used on the Continent after the invasion (top). Caterpillar tractors and bulldozers stored at an Engineer depot to be used after the invasion of France (bottom).] [Illustration] [Illustration: ENGLAND 20 GROSVENOR SQUARE, LONDON, U. S. Headquarters of the European Theater of Operations (top). U. S. enlisted men passing Number 10, Downing Street, residence and office of the Prime Minister of Great Britain (bottom). During the period of the build-up in the British Isles, activities and plans were formulated for the large and small units scattered throughout the United Kingdom in a group of buildings located near the American embassy in London. This group of buildings housed the offices of the personnel whose task it was to co-ordinate the activity and training of units and, in addition, to handle the problems relating to the build-up of supplies for the invasion.] [Illustration] [Illustration: ENGLAND A COLUMN OF HALF-TRACKS advancing along a road during the training period in England (top). The second, third, and fourth vehicles in the picture are 75-mm. gun motor carriages M 3. This was the first standardized U. S. self-propelled antitank weapon used in World War II, and provided high mobility for the 75-mm. gun. It was replaced in March 1944 by the 76-mm. motor gun carriage M 18, and in September 1944 was declared obsolete. Temporarily stored half-tracks (bottom). These vehicles were used as gun and howitzer motor carriages, antiaircraft gun carriages and personnel carriers.] [Illustration] [Illustration: ENGLAND ARMORED UNITS PARTICIPATING IN MANEUVERS in England. In the spring of 1944 intensified training was given to all units which were to take part in the invasion of Normandy. Light tank M 5A 1 (top), medium tank M 4A 1 (bottom). The U. S. tank was designed as a weapon of exploitation to be used in long-range thrusts deep into the enemy’s rear where it could attack his supply installations and communications. This required great endurance, low consumption of gasoline, and ability to move long distances without a break-down.] [Illustration] [Illustration: ENGLAND MEN OF A SERVICE SQUADRON SALVAGING A FUEL TANK from the wing of a P-51. These tanks helped to make the bomber escort planes into long-range planes which gave fighter protection to the heavy bombers. The tanks, the fuel from which was consumed first, were dropped when empty and the plane then used gasoline from its permanent tanks.]