Howitzer M2A1 & Carriage M2A1, 105mm The M2 and upgraded M2A1 were 105mm towed howitzers that served well throughout WWII. In fact, more than 8500 of these workhorse field artillery pieces were produced during the course of the war. They served as the USA’s standard light field howitzer, and one in five shells fired by the U.S. Army came from their muzzles. This weapon had a good reputation with soldiers thanks to its accuracy and hard-hitting punch. A typical infantry division had 54 such howitzers.