he 105 mm M2A1 (M101A1) howitzer was the standard light field howitzer for the United States in World War II, seeing action in both the European and Pacific theaters. Entering production in 1941, it quickly entered the war against the Imperial Japanese Army in the Pacific, where it gained a reputation for its accuracy and powerful punch. The M101A1 fired 105 mm high explosive (HE) semi-fixed ammunition and had a range of 11,200 metres (12,200 yd), making it suitable for supporting infantry
The gun fired semi-fixed ammunition, with 105mm Cartridge Case M14. The propelling charge consisted of a base charge and six increments, forming seven charges from 1 (the smallest) to 7 (the largest). Use of M1 HE rounds prepared for the 105mm howitzer M3 (same projectile and cartridge, but different propelling charge) was authorized.