From his first day of artillery school at Fort Bragg, North Carolina, on 13 APR 1944 until his last day of combat in World War II, Uncle dix was with Battery B of the 215th Field Artillery Battalion which had three such batteries: A, B and C.
The 155 mm Howitzer cannon weighed 6 1/2 tons and was towed from position to position by a 5 ton military truck which also carried the eleven man crew, the ammunition etc. Each battery consisted of six firing Howitzers. Each battalion therefore had eighteen Howitzers and ~ 198 soldiers. The maximum firing range for the standard 95 pound projectile was 9 miles.
There is a detailed article about the 155 mm Howitzer here (link) . An excellent videos which explains the function of the crew and demonstrates the Howitzer in action are here (link) and here (link) .