M1 8 in (203 mm) howitzer

M115 8 in (203 mm) howitzer

The M115 8 in (203 mm) howitzer, which was replaced by the M110 self-propelled howitzer, is a towed weapon developed prior to World War II as a heavy artillery weapon. The weapon uses NATO standard 203mm ammunition, and was used during World War II, in Korea, and in Viet Nam. In NATO service their prime mission was to fire nuclear rounds which have since been phased out of service.

The first American attempt to develop a 203mm gun had failed in the early 1920’s due to budgetary constraints. During World War I the US Army had determined that an 8″ field gun would be desirable, in 1919 a specification for this weapon was founded but all work was suspended in 1924.

The project was relaunched in 1939 as an answer to the German 17cm K18. Intended to be used in conjunction with the 240mm M1 howitzer, it shared with it many components, among them the mount and the breech. The 8″ Howitzer was the “partner piece” to the American 155mm gun, in that both used the same carriage to mount different barrels for different roles.

Tests of the prototype T3 howitzer began at Aberdeen Proving Ground in 1939 and the howitzer entered service as the 8 in Howitzer M1. The prototype T2 took a long time before being standardized as the M1 in January of 1944. The inner surface of the barrel was subjected to a high erosion by its shells, which increased dispersion and was detrimental to accuracy. Although it could fire further and launched a heavier shell than its German counterpart, production numbers remained limited and it was usually confined to training duties. The wheels are removed from the carriage when in use and it takes some time to prepare the M1 for travel or to place into a new firing position. the carriage is designed for high speed travel.

The answer to the German 170-mm. gun was the 8-inch gun, which had a range of 35,000 yards, outranging the 170-mm. by about 5,000 yards. The Caliber Board Report of 1919 had recommended the development of a long-range 8-inch gun along with the long-range 240-mm. howitzer, and the Chief of Field Artillery had asked the Chief of Ordnance in January 1940 to procure pilot models of both, but the Army’s interest in heavy artillery had lapsed in the early years of the war when the Germans were demonstrating so spectacularly the effectiveness of dive bombers and tanks. It revived after Tunisia, where the U.S. forces had come up against the 170-mm. gun for the first time. Returning from North Africa, General McNair on 15 May 1943 had stated, “Instead of artillery becoming an arm which is tending to fade out of the picture under the pressure of air power or tanks, it is there in the same strength and importance that it had in the [first] World War.”

The 240-mm. howitzer was standardized in the spring of 1943, the 8-inch gun in December 1943. General McNair considered the ammunition for the 8-inch gun unsatisfactory; there was also trouble with the carriage. Though originally it was thought that the same mount could be used for both the heavy howitzer and the gun, the 65-degree elevation for the howitzer could not be accommodated to the plus 10-degree elevation of the gun, and therefore another carriage for the gun had to be devised.

Field Artillery officers wanted to wait until the gun and carriage were improved before sending them to the battlefield. The Ordnance Department took the position that although improvements were desirable, the guns ought to get into action. General Campbell urged General Somervell early in July 1943 to speed the production of the 8-inch gun as well as the 240- mm. howitzer; a few days before Salerno General Barnes, the head of Ordnance’s Research and Development Division, told the AGF Ordnance officer that the guns were all right “and not to be using them is wasting a tremendous amount of firepower which is definitely needed in operations on the continent.”

It took Anzio Annie to clinch the argument, for until she spoke the theater was in no hurry for the big gun. When Brig. Gen. Gordon M. Wells, chief of Ordnance’s Artillery Division, visited the Cassino front during Christmas week 1943 he noted that the German 170-mm. gun outranged all Allied artillery in the theater, making it necessary to move the 155-mm. guns far forward for effective counterbattery action; that the 8-inch gun would no doubt provide the proper remedy; and that Fifth Army, though still concerned about the transportation problem, intended to request 8-inch guns “as soon as they are ready for issue.”

Four 8-inch guns arrived in Italy at the end of April 1944 and were assigned to the 240-mm. howitzer battalions. Two went to the Cassino front, two to Anzio. The ammunition for them arrived just in time for the big guns to add their roar to the great salvo from Cassino to the sea that heralded the beginning of the battle for Rome on 11 May. They silenced 170-mm. guns emplaced deep in enemy territory; they harassed areas the Germans had hitherto considered safe; and to intensify the effect on the enemy’s morale, Ordnance troops had bored holes in the windshield of the shell to produce a scream.

In the Anzio breakout, beginning 23 May, the 8-inch guns shattered power and railway stations in Albano, cratered roads, and generally hampered the retreat of the Germans. In moving the big guns and howitzers forward on both fronts in the drive for Rome, the T2 tank recovery vehicle justified the confidence the Ordnance Department had placed in it. The use of the 8-inch guns and 240-mm. howitzers on the Italian front was nevertheless comparatively brief. After the capture of Rome, the shipment of guns to the high-priority European theater began and by November 1944 none of the 8-inch guns and 240-mm. howitzers were left in Italy.

The original WW2 M1 series (which became the M2 with some manufacturing improvements) put a 95lb/42kg HE shell to 25,000 yards/23km while the 8″ – also designated M1 and later M2 – fired its heavier 203mm calibre 200lb/90kg shell to 18,000 yards/17km. Both guns were the mainstay of American and allied heavy artillery units and served for many years post-war with US forces as well as being widely distributed to America’s allies.

After the Second World War the complete weapon was redesignated the Howitzer, Heavy, Towed: 8 in: M115. They were redesignated as M115 for the 8″ and this gun was used in its original 25 calibre format in the early model M110 series self-propelled guns. As such it served for many years, with the M115 in towed form being still in service in the 1990s which shows what a solid and reliable gun it was. It was also capable of firing nuclear rounds. Its 155mm partner was also used for many years, under its new title of M59. The same carriage was also adopted by the British Army to mount the 7.2″ Howitzer Mk 6.

Variants of the M110 with a longer barrel include the M110A1 (no muzzle brake) and the M110A2 (fitted with muzzle brake). In most countries the M115 and the M110 have been phased out of service due to short range. The carriage of the 8 in howitzer is also used to mount the 155 mm Gun M1 (Long Tom), which is still in use with some armies.

The carriage consists of equilibrator assemblies, elevating and traversing mechanisms, two single-wheel, single-axle heavy limber, two-axle bogie with eight tyres and two trails. Four spades, carried on the trails, are used to emplace the weapon. In recent years some armies have towed the weapon without the limber.