Soldiers of the U.S. 734th Field Artillery Battalion with truck

Soldiers of the U.S. 734th Field Artillery Battalion with truck. The battalion were equipped with the M1 155mm gun, known as a "Long Tom" (an appellation with a long and glorious tradition in the U.S. artillery.) It combined long range, accuracy, and hitting power with a well designed, mobile carriage. Nearly all US artillery battalions were organized with three firing batteries and a total of twelve tubes. The exception was the eighteen-tube armored field artillery battalion and the six-tube 8" gun and 240mm howitzer battalions. A major advantage for the American artillery was that it was fully motorized and highly mobile. All 105mm and 155mm howitzer battalions in the ETO were truck-drawn, although a Table of Equipment (TE) for a tractor-drawn 155mm battalion existed. The 155mm gun battalions were almost all tractor-drawn, although a few evidently were also truck-drawn. The 4.5" gun, 8" gun, 8" howitzer, and 240mm howitzer battalions were all tractor-drawn, although, again, a TE for truck drawn battalions existed. The standard prime mover was a two-and-one-half ton truck for the 105mm and a 4-ton Diamond T truck for the 155mm howitzers. Tractors included the M5 thirteen-ton prime movers, which were utilized for the 105mm M2 howitzer, the 4.5" gun, and 155mm M1 howitzer, and the M4 eighteen-ton hi-speed, full-track, heavy prime mover, which was utilized for the 3" AA gun, the 90mm AA gun, the 155mm Long Tom gun, 8" howitzer, 8" gun, and 240mm howitzer. Redundant M3 medium tank chassis, without armament, and M31 and M32 armored recovery vehicles were also utilized as prime movers for the heavier artillery pieces. Non-divisional artillery battalions were normally subordinated to field artillery groups. The groups were formed in 1943 from the headquarters battery of the broken up field artillery regiments. The field artillery group consisted of an H&H Battery, with a command element and a fire-direction center element, and a Service Battery. A group was usually assigned from two to six battalions, although one or more of the battalions might be attached for direct support of an individual division. Usually, the groups were assigned howitzer and gun battalions of companion caliber, that is, 155mm howitzers were grouped with 4.5" guns, 8" howitzers with 155mm guns, and 8" guns with 240mm howitzers. The normal ratio was one gun battalion for every two howitzer battalions, although this was not always firmly adhered to. Separate 105mm howitzer battalions were normally grouped together, but were almost always assigned to direct support of divisions. The 155mm SP gun battalions were assigned to groups as the tactical situation warranted, or were frequently attached, by battery or battalion, to armored or infantry divisions. This picture was taken by H.W. Luetjen who served in the 734th FA.

Source :
http://www.lonesentry.com/photoalbums/luetjen/
http://www.militaryhistoryonline.com/wwii/usarmy/antiair.aspx