The M109 is, of course, primarily an indirect fire weapon, used to support the direct fires of maneuver forces. On occasion, however, they might be called upon to deliver direct fires. That’s usually a very bad thing, having to fight for the guns, as it were.
As such, it certainly makes sense to train for it from time to time. Plus, it’s fun to watch big shells go boom at a relatively close range.
The US doesn’t issue anti-tank rounds for its howitzers, but the Soviets did. Typically, two or three HEAT rounds would be included in the basic load of a Soviet howitzer.
The rule of thumb for HEAT round penetration is diameter of the round, multiplied by six, is the rough equivalent in RHA. So a six inch (152mm) round should have a penetration of about 36″ of RHA. Not many tanks can handle that. Of course, direct fire in a howitzer is pretty short. Like, around 1000m. Tanks have a somewhat longer effective range.
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.
Craig here. XBrad opened the door (and threatened to push me through it) with regard to heavy howitzers noting the Republic of China use of what is basically the US M-1 240mm howitzer of World War II vintage. There’s a bit of irony finding those howitzers defending the shores of Taiwan. To appreciate such, let me discuss the background of those big old howitzers.
By the close of the American Civil War, heavy howitzers faded from the seacoast batteries of most nations. The United States retained a rather effective seacoast defense weapon known as the Columbiad which combined the ballistics of guns and howitzers. But most nations turned to higher velocity, direct fire rifled breechloading guns. Almost alone among major powers, the Americans produced several large-caliber mortars for coast defense.
During the “First War of the Twentieth Century,” the Russo-Japanese War of 1904, the Japanese laid siege to Port Aurthur (now in Manchuria, mainland China). Firing on the Russian far east stronghold were batteries of relatively new breech-loading rifled artillery, to include some of these big boys:
These large siege guns not only caused great damage to the Russian defenses, but also worked over ships in the port. The 28cm (11-inch) howitzers were products of the great German armaments manufacturer, Krupp. Designed for use in the defenses of Tokyo, the Japanese reallocated the howitzers when the Russian fleet ceased to be a threat after the battle of Tsushima. And these big howitzers did a job on the Russian fleet in Port Arthur.
European observers watched this development with great interest. In the years before World War I, all the great powers produced their own heavy siege howitzers. Although these could pull double duty as seacoast weapons, most of the continental powers looked for something to reduce the reinforced concrete fortifications on land. Of this “generation” of heavy guns Schneider, the French armaments manufacturer, produced a 280mm howitzer marketed for the Russians who were then re-arming. A few of these weapons ended up in French service during World War I.
When the US entered World War I, planners saw the need for a heavy howitzer to work over the German defenses on the western front. Furthermore, the Ordnance Department saw a need, beyond the wartime requirement, for a new heavy howitzer for mobile coast defense batteries. After some negotiation, the Army struck a deal with Schneider for license production of a 240mm version of their howitzer. Schneider built one example in France and shipped it to the US. And the French also sent engineers to the US to help start the production. Yet the project never picked up momentum. Only the original French gun was on hand at the time of the Armistice.
But with the mobile coast defense requirement in mind, the M1918 9.5-inch (240mm) howitzer project continued after the end of hostilities. Eventually a few rolled out of the factory. And only with a wink and a nod, we might call this “mobile.”
And I’ll start the unsubstantiated rumor the entire outfit was cleared for air-drop….
Only took six hours for the crew to set up this beast. And in action she looked intimidating.
The M1918 could throw a 346 pound shell over 17,000 yards. State of the art for that day. Only one problem… when the first M1918 went to the range for proofing, the cannon blew up! And follow-up corrections failed to resolve many of the gun’s problems. Only after a long gestation were 330 examples produced. Some of these guns went to Hawaii where concrete pads allowed wide traverse and coverage of potential enemy approaches.
But for the most part, the Army shunted these howitzers to the storage yards. I’m not certain, but don’t think any were even offered up as Lend-Lease in 1940.
With America’s entry into the next world war, clearly the M1918 was a dated design. So back to the drawing boards went the Ordnance Department. The main drawback to the M1918 was (duh!) mobility. In the inter-war period, experiments to match the M1918 to high-speed towed carriages and even self-propelled platforms failed. But lessons learned projected into a new design, as XBrad highlighted – the M1 240mm howitzer.
Regardless of what you downsize, big cannons are just… well big. The Army tried several different carriages, but finally settled on a two load arrangement. In the picture above the barrel, with recoil system, is on a six wheel trailer. A similar trailer transported the carriage. The concurrently developed M1 8-inch gun used the same carriage and transport. The M1 240mm howitzer weighed 64,700 pounds in action and fired a 360 pound shell to over 25,000 yards. The M1 8-inch gun weighed 69,300 pounds and pushed a 240 pound shell to 35,600 yards (with a 90 pound super charge).
These battery mates saw heavy action in the Anzio beachhead in 1944, firing counter-battery against the German railway guns.
These big guns followed the allied advance through Europe and also served in the Pacific.
But the “system” was not mobile enough for the desires of US planners. Once again, someone figured to put the big cannons on tracked carriers. Based on the M26 Pershing Medium (originally Heavy) tank chassis, the T92 240mm Howitzer Motor Carriage and the T93 8inch Gun Motor Carriage made an appearance in 1945. Despite orders for several hundred, and designation of “limited standard,” only a handful rolled out before the end of the war.
Even in the face of air power lessons-learned during World War II, the Army still figured super-heavy artillery had some place in 1946. In particular, the Ordnance Department considered the newest technology in regard to counter-battery, interdiction, and coast defense. After all, everyone was giddy about the “atom” in those days. So out came the T1 240mm Gun.
And not quite so happy with that caliber, the Army turned to the T71 280mm which eventually became the M65 280mm Atomic Cannon.
Or for those who like the ‘splodie fast forward to the 9 minute mark:
While the new carriages (based off some German heavy gun and railway carriages) were more mobile than the World War II types, the mushroom cloud effect sort of made that irrelevant. A few dozen of these entered service, but soon the Army turned to rockets and missiles that offered a little better range (well with the exception of that Davy Crockett thing). So by the 1960s the “big guns” of the field artillery were 8-inch howitzers and 175mm guns.
But consider the turn about here. The Armies and the cannons change, but from one century to another there are still those big howitzers placed to defend a Chinese coastline.