The history of the M101 105mm towed howitzer can be traced to as early as 1919, but due to funding problems, it was not placed into production until much later. It entered service with the United States Army in 1940. By the end of World War II, over 8,500 M101 howitzers were built and were continuing to be produced by the Rock Island Arsenal until 1952 after over 10,000 M101s had been built.

The M101 is a hardy and reliable gun with a moderate range and rate of fire. The lifespan of the weapon is approximately 20,000 rounds and there is a large stockpile of units and parts for this weapon. The M101 also features a horizontal breechblock that was used along with a percussion firing system. To achieve consistent stability, the recoil system was mounted under and over the short barrel. The reliability of this gun and high production amounts led to many different countries acquiring it. At least 67 countries have purchased this howitzer, making it one of the most successful field pieces ever produced.

M101 105mm towed howitzers used the standard NATO 105mm round ammunition. The propelling charge consists of a base charge and six increments that form seven charges from one (the smallest) to seven (the largest). Additional ammunition used by the weapon include:

• HE – HE M1 Shell

• HEAT-T – HEAT M67 Shell

• Smoke – HC BE M84 SHELL, WP M60 SHELL, FS M60 SHELL

• Smoke, colored – BE M84 Shell

• Chemical – H M60 Shell

• Practice – Empty M1 Shell

• Drill – Drill Cartridge M14

Elevation of the M101 ranges from -5 degrees to +66 degrees with a traverse of 46 degrees. The range of the M1 projectile has been reported at 12,325 yards, while the M548 projectiles had a range of 15,965 yards. A rate of fire of 10 rounds per minute can be achieved with 3 rounds per minute in sustained fire.

M101A1 105mm Light Howitzer
A popular variant of the M101, the M101A1 is a general-purpose, light field artillery weapon that consists of a 105mm M2A2 howitzer cannon, an M2 series recoil mechanism, and a carriage. It may be used for either direct or indirect firing. The cannon is mounted atop the recoil sleigh assembly, and the firing mechanism is a continuous pull (or self-cocking) type that is activated by pulling on a lanyard. The cannon is single-loaded, air-cooled, and uses semi-fixed ammunition.