The M101A1 fires 105 mm high explosive (HE) semi-fixed ammunition and has a range of 12,330 yards (11,270 m), making it suitable for supporting infantry.

The Army had an intention to replace all 75 mm gun-howitzers in its divisional and non-divisional field artillery regiments with 105 mm pieces, but a lack of appropriations stalled the idea and eventually forced it to be completely abandoned by 1929; a limited plan developed in 1925 envisioned re-equipping three regiments, but by 1933, only 14 M1 howitzers had been manufactured.

[1] In 1939, the new howitzer cost $25,000, which was three times more than a 75 mm field gun M1897 on M2 carriage, and its adoption required procurement of a colossal amount of new ammunition (War Department estimate of $26 million).

[2] The gun was designed to be very durable and was therefore heavy for its caliber,[3] but studies after 1943 found that after prolonged firing, the muzzle end of the barrel was prone to cracking.

[10] The Canadian Forces procured at least 60 US made M2A1 howitzers, beginning in 1952, and also had Sorel Industries of Canada produce 232 of a slightly modified M2A2 version, starting in 1955.

[11] A number of M2/M101 howitzers were used by the Socialist Federal Republic of Yugoslavia and approximately 50 were inherited by Croatia, of which four are still in use for training with the Croatian Army.

[15] The German Army adopted the M101 howitzer in a modified form in March 1956, designated Feldhaubitze 105 mm M1A2 (Bw).

[16] Using components made by Rheinmetall, the new howitzers had a longer, un-counterbored 27-caliber barrel, a large single-baffle muzzle brake, and a larger gun shield.

[citation needed] Several M101 howitzers are still in use with the Armed Forces of the Philippines and are normally used to battle rebels in Luzon, Visayas, and Mindanao.

After the test, the U.S. ambassador Philip Habib arranged the meeting of South Korean chief secretary O Won-cheol and colonel Montgomery from the Joint U.S. Military Affairs Group-Korea.

South Korea refused and pursued domestic design, but the two nations eventually signed an agreement for technology transfer in September 1973.

In November 1975, the reinforced variant experienced barrel breakdown; the failure led to the invitation of American engineers in January 1976 for an overview.

After 1.5 months of inspection, the engineers suggested the Eighth United States Army replace South Korean copy with the original M101A1 design.

The U.S. then provided its technical data package to South Korea, which quickly readied mass production of the howitzer before the year ended.

[22] France and the State of Vietnam used M2A1 howitzers during the First Indochina War, as did the Viet Minh guerilla forces they fought against, who were supplied with at least 24 by the People's Republic of China, along with other captured American artillery pieces and mortars formerly operated by both Nationalist Chinese forces (the Kuomintang military) and US troops fighting in Korea.

[citation needed] Today upgraded M2A1 howitzers (some of which have been mounted on trucks and employed as self-propelled artillery) are still being used by the People's Army of Vietnam (the PAVN).