In the post-World War 2 rebuilding period, the Italian Army found itself in need of a new, lightweight towed artillery system to cover an indirect-fire requirement for mountain and airborne troopers. The storied concern of OTO-Melara, established in 1905, returned with a new "pack" howitzer of 105mm caliber during the mid-1950s. The type would be lightweight enough to be air-transportable and fire standardized High-Explosive (HE) shells out to nearly 10,000 yards. The result of this work became the "Mod 56".
The Mod 56 tipped the scales at 2,840 lb and sported a barrel of 4.9 inches long. Overall length of the system reached 12 feet and width was 4.11 feet with a height of 6.2 feet. The typical operating crew numbered seven and a small gun shield was added for limited protection. The gun tube sat on a two-wheeled, rubber-tired split trail carriage and the tube itself was capped by a multi-slotted brake. The breech was accessed by way of a vertical sliding block and recoil aided by a hydropneumatic arrangement under the barrel. Elevation and traverse functions were built into the mounting setup allowing for an elevation span of -7 to +65 degrees and 56 degrees from centerline (respectively) to be reached. Projectile muzzle velocity reach 1,360 feet per second and the gun could sustain a rate-of-fire of 10 rounds-per-minute for short periods of time.
As a lightweight battlefield artillery piece, the Mod 56 was an infantryman's friend in that it could be relocated across short distances by the crew itself (not requiring a mover vehicle). Additionally, the weapon broke down relatively quickly into twelve key components and could be moved, rebuilt, and fired at a new location in this manner (this access also aided in its maintenance and cleaning). Beyond its direct-handling by troopers, the gun could easily be slung under the belly of a helicopter and transport at speed.
However, the system's light design came a price for the guns were quickly shown to fracture during periods of heavy sustained fire. In this way they lacked the long-term durability seen in competing designs such as the American World War 2-era M101 Pack Howitzer system (detailed elsewhere on this site). Indeed, the Italians themselves moved on from the Mod 56 to the modern M2A1 (M101A1) in a short period of time.
This is not to say that the Italian weapon held little merit for a modern frontline fighting force - the Mod 56 was adopted by a slew of global operators including the United Kingdom (as the "L5"), Australia, and Canada and proved a fixture across Europe during the Cold War period. Today, the gun still sees service with second-rate military powers like that of Argentina, Botswana, Nigeria, and Zambia though it has been given up by major defense players like France, Germany, and India.
Australian units deployed the howitzer during the 1948-1960 "Malayan Emergency" and Malaysia deployed these guns, in turn, during the "Second Malayan Emergency" of 1968-1989. British forces deployed the system in the "Aden Emergency" of 1963-1967 and Argentina fielded the guns in anger during their "Falklands War" against Britain in 1982. The Vietnam Conflict was witness to the Mod 56 being used by both Australian and New Zealand forces for a time. China generated a local copy of the Mod 56 for export sale.