Thus far discussing the US Army’s field artillery of World War I, I’ve focused on the divisional field guns. These were the more important weapon, in terms of numbers. But as was custom (indeed even up through World War II) armies often paired low trajectory, high velocity guns with high angle, low velocity howitzers. The American Expeditionary Force (A.E.F.) was no exception.
Recall that Colonel Charles Summerall wanted six batteries of either 3.8- or 4.7-inch howitzers to augment the twelve batteries of field guns in every division. But the officers of the A.E.F. wanted 6-inch howitzers at the division level. Specifically the A.E.F. officers preferred the French 155mm howitzer (technically 6.1 inch) produced by the Schneider firm. A simple comparison of the American and French howitzers demonstrates the wisdom of the A.E.F. choice:
- American 3.8-inch howitzer Model 1915 fired a 30 pound shell to 6,100 yards and weighed 2,040 pounds in action (without limber)
- American 4.7-inch howitzer Model 1908 fired a 60 pound shell to 7,000 yards and weighed just under 4,000 pounds.
- American 6-inch howitzer Model 1908 fired a 90 pound shell to 9,000 yards (or a 120 pound shell to 6,700 yards) and weighed 7,200 pounds.
- French Canon de 155mm Court mle 1917 fired a 95 pound shell to 12,300 yards and weighed 7,600 pounds in action.
With only a small increase in weight, the French gun added one-third more range. More importantly, the Americans had precious few of their howitzers on hand and the French offered the Schneider howitzer in quantity. The Americans ordered 1,361 howitzers of this type, designating them M1917, from the French, who delivered 772 by Armistice Day.
The type dated back to a 1910 Schneider howitzer for export to the Russians. After the summer of 1914, the French desperately needed howitzers for use along the static, entrenched fronts and accepted the export model into service as the Canon de 155mm Court mle 1915S. The original gun fired semi-fixed ammunition with a brass case. As the French faced a brass shortage and preferred bag charges for large calibers, Schneider redesigned the breech. The resultant weapon became the mle 1917 and Schneider began large scale production. The original French guns, including those sold to the A.E.F., had a curved shield.
The barrel was a typical French built up type. Note the “muzzle ring” that became a distinctive feature of this weapon.
The breech block was a simple interrupted screw type that swung out to the right. The block itself was very similar to that used on the contemporary 155mm Grand Puissance, Filloux (GPF) gun … but I’m getting ahead a few pots.
To facilitate the use of bagged charges, the breech used a DeBange style obdurator pad. As seen in the diagram, an asbestos ring (solid black) filled with fluid fit between two sections of the block along with metal rings. The pressure of firing pushed the “mushroom” head of the block and compressed the asbestos ring, thus sealing the breech.
The entire barrel assembly sat upon and recoiled down a cradle. Note the trunnions and elevating segments attached to the cradle. These allowed the barrel plenty of elevation while not constraining recoil travel.
Inside the cradle sat the recoil system. This consisted of two tubes – the lower tube filled with hydraulic fluid with a piston attached to the recoil rod; and an upper tube filled with a mix of compressed air and fluid.
When fired, the piston compressed the fluid, forcing it through a connector into the upper tube. The air compressed, slowly arresting recoil. As the air decompressed, it forced fluid back into the lower tube thus forcing the piston and the barrel back to the forward position.
The system did require careful monitoring of fluid levels and air pressure.
Going back to the 7,600 pound weight of the gun, this required an eight-horse team for movement. To balance the piece on the limber, the crew disengaged the recoil system, and pulled the barrel back on the cradle. However for towing behind trucks or tractors, the barrel could remain forward.
Perhaps because it lacked any elaborate components, the Schneider howitzer served with few complaints.
Realizing French production would not meet long term needs, the Americans began license production of the Schneider howitzer in 1917. The Americans opted for a flattened gun shield, rubber tires, pivoting spade, and different firing mechanism. The Americans also “improved” the hydraulic fluid and pressure monitoring systems. With such modifications the howitzer went into production as the M1918.
The Army parceled out production by components with initial orders going out in the summer of 1917. For most components, production moved swiftly. Indeed the American Brake and Shoe Company produced excess barrels for sale back to the French in 1918. But one component again delayed the overall production – the recoil system. In order to work, the interior of the tubes required a fine polish and exact fit to the piston diameter. This was not an issue for France, where everything was hand fitted – and guns rolled off the line in handfuls. But such was not easy for American assembly lines where everyone expected to see hundreds of guns produced over the span of weeks. One historian described the challenge:
It is scarcely fair to a modern hydropneumatic recuperator to say that it must be finished with the precision of a watch. It must be finished with a mechanical nicety comparable only to the finish of such a delicate instrument as a navigator’s sextant or the mechanism which adjusts the Lick telescope to the movement of the earth.
Eventually the Dodge Motor Company sorted out a way to mass produce the system.
Compared to the 75mm guns, that of the M1918 155mm howitzer is at least one of partial success. By July 1918, Dodge delivered quantities of the troublesome recuperator. The first regiment of 155mm howitzers had begun embarking for France when news of the Armistice came. As with other American cannon production projects, had the war gone into 1919, more of these would have followed.
In closing, here’s a clip showing the Schneider howitzers in action.
Like the 75mm guns, these 155mm howitzers formed the backbone of American artillery between the wars and saw service in the initial stages of World War II.