The M1A1 Pack Howitzer was the standard howitzer for American forces in World War 2. The Pack design actually traced its roots back to the howitzer development of World War One, standardized in the American Army post-war as the M1. The M1A1 of the Second World War featured a short barrel, could reach a sustained rate of fire of 3 to 6 rounds per minute with a capable crew, and had a range of roughly 9,610 yards (8,790 meters). The system was purposely engineered to be light, easily transportable and operated by a small crew (which worked well in the favor of light divisions such as airborne units as evident in the M8 variant of the Pack). The high explosive shell of the M1 Pack Howitzer weighed 6.3 kilograms. The weapon system could be used for suppression, assault, defense and limited anti-tank duty. Further developments enabled better cross-country mobility.
Pack howitzers garnered their 'Pack' designations by the idea that pack animals could tow the lightweight system (most common in World War One but not uncommon in World War Two for either side). The system was designed to be easily taken apart in multiple pieces (the M1 carriage could be taken down to a total of six parts while the gun system could be taken down to nine parts) for this very purpose. The M1A1 first utilized the aforementioned M1 Carriage, which featured wooden spoke wheels. Later versions implemented into the follow-up M8 Carriage utilized rubber treaded tires on metal wheels.
The M1A1 saw action in Arnhem with the British, being dropped by glider in Operation Market Garden. British troops also trained Yugoslavian partisans in the use of the weapon system (seeing some success in the mountain warfare role). The M1A1 saw action in the far east jungles of the Pacific Theater. The ability of the system to be able to be broken down made it most advantageous in mounting amphibious assaults needing artillery support immediately upon landing on the beaches.
M1A1 Pack Howitzers were also trialled on halftrack chassis and utilized to great effect in this role as well. Overall, the M1A1 became a classic piece of American artillery design. Portable, potent and very versatile, the system went on to see a great many years of frontline service as the standard light artillery weapon system.