Take a close look at this often reproduced photo of US troops in action during World War I:
The weapon in this scene is a M1916 37mm Infantry Gun, sometimes called a “1-pounder” by U.S. authorities. While technically a “gun” it was not officially considered “artillery” during the war. Each infantry regiment had a platoon of three infantry guns assigned to the headquarters company. Their employment gave the basic infantry formations “heavy weapons,” establishing a practice that continues today.
Prior to the 20th century, infantry formations were pure “leg” infantry with few, specialist troops organic to the tale of organization even at the regimental level. New technologies brought new weapons to the infantry in peacetime. But the intensity of combat became the most important factor bringing specialty platoons to the regiments and battalions.
After the Western Front went to the trenches, infantry commanders on both sides complained that conventional artillery could no longer keep pace with the infantry. The oft cited problem involved reduction of enemy machine-gun nests. Cratered no-mans-land prevented forward movement of artillery without engineer support. And the communications systems of the day would not reach to forward assault elements to facilitate careful direction of the artillery. The infantry needed a light-weight gun system.
The Germans had one solution on hand – the 7.85cm leichte – an early modern mortar. But these were engineer specialist weapons designed for high angle fire. As a temporary solution, the Germans dismantled a large number of obsolete 3.7cm Gruson-Hotchkiss Revolverkanone (similar to the Gatling gun in concept with five revolving cannon barrels). They fitted each barrel (so a one for five exchange in the number of guns) with a basic breech assembly and mounted the new Grabenkanone on a simple frame with a shield – without recoil system. Another variant, named the Sturmbegleitkannon, arrived in 1915 and placed the gun on a light field cart for movement forward with assault teams. The setup weighed 700 pounds. Later the Germans introduced heavier 7.7cm Infanteriegeschutz or infantry cannons.
Facing a similar tactical need, the French fell back on a pre-war gun design. The lineage of the weapon is somewhat sketchy, but the Puteaux Arsenal designed a light 37mm gun sometime in the 1890s. The gun found no uses until 1916 when a French army officer adapted it to a light-weight mounting for use by the infantry.
The basic design used a rotating breech block (a miniature version of the 75mm M1897). Like the larger gun, the breech block rotated inside a threaded, over-sized breech ring. The block had a cut out that, when rotated, opened the breech and acted like a tray for loading. A hydro-spring system fitted below the gun barrel provided recoil control. The gun and recoil system sat upon a light, low-profile tripod mount (note the flash suppressor often removed in American service).
In French service, a gun shield on the front of the tripod protected the two-man crew.
But this two was usually removed in American service. Crews placed the entire setup on a small, two-wheeled cart for displacement to new firing positions. Equipment included an ammunition cart with fourteen boxes of sixteen rounds each.
The gun, firing tripod, and cart weighed about 360 pounds. The ammunition cart, while doubling the total, remained handy given the number of troops assigned. If tactical situations required, the entire setup was broken down into several loads for hand carry.
The mounting allowed for 21° elevation and 14°. Left traverse covered 16°, while the gun swept 22° to the right. Maximum range was 3,650 yards with an high explosive round. The crew used a telescopic sight for direct shots and a gradient sight for indirect fires.
The gun crew was a squad consisting of one sergeant, one corporal, and nine privates. Supervised by the Sergeant, the corporal and one private worked the gun. The rest hauled ammunition. Three of these squads formed the “1 pounder platoon” in the headquarters company of each infantry regiment under the American divisional table of organization in 1918.
When America entered the war, the French had the 37mm in full production as the “Canon d’Infanterie de 37 mle de 1916 tir rapide Puteaux (TRP)”. The American Expeditionary Force purchased 841 of these from the French to meet immediate needs, officially designating them as 37mm Infantry Gun M1916. As with the bigger guns, the Americans also purchased production rights anticipating production on a massive scale with contracts totaling over 4,000.
The wartime production board split responsibility for the gun into several contractors. Poole Engineering & Machine Company of Baltimore, Maryland produced the barrels, with subcontracts to the Maryland Pressed Steel Company of Hagerstown, Maryland. Krasberg Manufacturing in Chicago produced the breech assembly. C.H. Cowdery Machine Works of Fitchburg, Massachusetts made the recoil mechanism. International Harvester produced the axles and wheels in a Chicago factory. Also in Chicago, the Universal Stamping & Manufacturing Company built the carriage trails. Collectively these vendors provided 826 guns by September 11, 1918. Three hundred American made guns were in France at that time.
The 37mm M1916 also armed some of the first American tanks to see combat.
Although none of these saw action in the war, American vendors produced some 1,200 modified M1916 guns during and after the war for use on the license built M1917 tanks.
After the Great War, the 37mm guns remained in service as part of the regimental organizations. To save costs, the Army developed a .22-caliber training adapter. National Guard and ROTC units trained with these, in some cases on indoor ranges. The Army also evaluated the 37mm as a possible anti-tank gun during the inter-war years. Development of an armor-piercing round soon branched into the search for a proper anti-tank gun of the same caliber. Interestingly, the Germans had made the same leap with the same caliber. And eventually the Americans would borrow that concept (although not the gun itself as some would lead you to believe) as the M3 37mm anti-tank gun. As war clouds gathered for World War II, the Army brought these old infantry guns out of the warehouses. A new generation of gunners trained on the 37mms, while more modern weapons entered production. Some of the M1916s saw action in the Philippines opposing the Japanese invasion in 1941-42.
The old 37mm, with its original role superseded and its performance eclipsed by modern guns, was the basis for early American tank and anti-tank guns.