Primary function: Light, towed, general purpose field artillery weapon used as a contingency weapon during Marine Air Ground Task Force deployments which are not conducive to mobility deficiencies of the M198 155mm Howitzer.
Manufacturer: Rock Island Arsenal
Length: 19.5 feet (5.94 meters)
Width: 7.25 feet (2.21 meters)
Height: 5.66 feet (1.73 meters)
Weight: 4,980 pounds (2,260 kilograms)
Bore diameter: 105 mm
Maximum effective range: 6.99 miles (11.27 kilometers)
Rates of fire:
Maximum: 10 rounds per minute
Sustained: 3 rounds per minute
Unit Replacement Cost: $196,341
Marine Corps Inventory: 248

Features: The M101A1 105mm Light Howitzer, Towed is a general purpose, light field artillery weapon consisting of a cannon, 105mm howitzer (M2A2); recoil mechanism, M2 series; and carriage, 105mm Howitzer, M2A2. It can be used for direct or indirect fire. The cannon consists of a tube assembly, breech ring, and locking ring. The cannon is mounted on the recoil sleigh assembly. The firing mechanism is a continuous pull (self cocking) type activated by pulling a lanyard. The cannon is single-loaded, air-cooled and uses semi-fixed ammunition. The carriage is of the single axle and split trail type. The trails are divided at emplacement, but are drawn together and locked during travel. A drawbar is provided for securing to a prime mover. The carriage consists of an equilibrator, shield, elevating mechanism, cradle, gear, elevating arcs, traversing mechanism, top carriage, wheels, and trails. The recoil mechanism is a constant hydropneumatic type shock absorber that decreases the energy of the recoil gradually and so avoids violent movement of the cannon or carriage. It is installed in the cradle of the carriage.

The 105-mm. Towed howitzer most often served in the direct support role. Its light weight, dependability, and high rate of fire made it the ideal weapon for moving with light infantry forces and responding quickly with high volumes of close-in fire. Units were initially equipped with the M101A1 howitzer, virtually the same 105-mm. Howitzer that had been used to support U.S. Forces since World War II. In 1966 a new 105-mm. Towed howitzer, the M102, was received in Vietnam. The first M102's were issued to the 1st Battalion, 21st Field Artillery, in March 1966. Replacement of the old howitzers continued steadily over the next four years.

Many of the more seasoned artillerymen did not want the old cannon replaced. Over the years they had become familiar with its every detail and were confident that it would not disappoint them in the clutch. Old Redlegs could offer some seemingly convincing reasons why the M101 was still the superior weapon: its waist-high breech made it easier to load; it had higher ground clearance when in tow; but most important, it was considerably less expensive than the M102. Their arguments, however, were futile. The new M102 was by far the better weapon.