High explosive mortar shell

While the principal mission of the mortar battalions was the dispersion of toxic agents and smoke, the CWS was of the opinion that the battalions could be profitably used to fire high explosives in support of the infantry. Before any such assignment was possible two preliminary steps were necessary. First, the War Department would have to approve a military requirement for a high explosive (HE) shell for the 4.2-inch mortar, and secondly, the Army Ground Forces would have to be convinced that the 4.2-inch mortar could be used to advantage in supplementing the 105-mm. howitzer in close support of the Infantry. 

Photo 8.4 Top 81-mm illumination mortar shell. Middle 3-inch Stokes chemical mortar. (Note most WWI mortars had no fins and may be mistaken for pipe. Bottom 60-mm high-explosive mortar. Fuses are often buried separately from ordnance items, contain impact-sensitive explosives, and are generally brass or aluminum, undetectable with magnetometers. Photo by Alvin Harris... 

Minen-bombe, /. mine bomb, high-explosive bomb, -gas, n. mine gas. -granate,/ mine grenade, -korper, m. Mil.) shell body, -pul-ver, n. blasting powder, -werfer, m. trench mortar. 

If no other sources exist, artillery and mortar shells, bombs, land mines, and other munitions may be cannibalized for the high explosives they contain. These munitions usually contain cast explosives, which require extra strong blasting caps or boosters to detonate. However, some of the simpler cannibalization techniques will be discussed. 

Uses Substitute for NTA or NTO, or in combination with for the preparation of explosives charges for use in a variety of applications including artillery shells, mortars, land minds, and missile warheads. Even though 5-NDTT is quite expensive to manufacture, it has excellent resistance to shock, friction, and percussion, making it very useful for the main component of high explosives especially for missiles. ... 

In the process of CWS expansion gray areas of mission responsibility were clearly defined, much of this work done under the direction of Maj. Gen. William N. Porter who became Chief, Chemical Warfare Service, in May 1941. This effort to define responsibilities resulted in expanded duties for the CWS, for example, development of a high explosive shell for the 4.2-inch mortar and the acquisition of complete responsibility for the incendiary bomb program. In 1941 the War Department gave the CWS the mission of biological warfare research. 

At the end of May, Shadle expressed his satisfaction with the chemical offensive potential and ammunition status in the North African theater. His view seems to have been overly optimistic since smoke pots, tear gas, and HC smoke grenades were the only ammunition items available in sufficient supply. All the chemical supply officers reported urgent requests for unavailable white phosphorus grenades. The Twelfth Air Force reported limited quantities of ANM50A1 4-pound incendiary bombs, a few Mja yoo-pound incendiary bomb clusters, and a considerable number of My4 loo-pound incendiary bomb clusters. There was no other chemical ammunition in the theater although the New York port had promised that 120 days supply of high explosive and smoke shell was en route for the three chemical mortar battalions which had recently arrived in the theater. Aside from a small amount of artillery shell stored by Ordnance, no toxics were available in the theater and none was scheduled to arrive until the fall of 1943. The March theater plan for gas warfare, the first such plan, was based on meeting possible enemy gas attack with this plainly inadequate supply of artillery shell. The new War Department policy for retaliation in event of enemy initiation of gas warfare called for the use of aerial munitions as the principal gas weapons. Shadle s satisfaction with the toxic supply status can be explained by the fact that he did not con-... 

As the combat period approached, Colonel Unmacht and his stafiF turned their attention from numerous projects in gas warfare defense and decontamination to the nontoxic chemical weapons and munitions. Their work on the flame thrower tank, and later on stabilized flame thrower fuels, was the outstanding overseas development work of the worldwide CWS. Unmacht was a strong proponent of the use of the 4.2-inch chemical mortar with high-explosive shell, and the development, testing, and combat supply of a landing craft mortar mounting for Pacific amphibious operations represented one of his achievements in the field of combat support. The mortar gun boat development was also a noteworthy example of Army-Navy co-operation. 

The determination, mentioned above, to convert the chemical weapons units to the 8i-mm. mortar naturally interrupted negotiations regarding the HE 4.2 mortar shell. A personal conference between General Porter and General Marshall, Army Chief of Staff, resolved the issue in favor of the 4.2-inch mortar, a decision followed by steps to equip the mortar battalions with the approved weapon. Later came the authorization to produce a high explosive filling for the 4.2-inch mortar shell. ... 

The high-explosive shell fired by the mortar company proved just as ineffective against the fortifications around Metz as it had against Siegfried Line installation at Aachen. This result was not surprising 500 and 1,000-pound aerial bombs also bounced harmlessly off the concrete and steel of the fortifications. ... 

States—had been activated, a fourth company having been lost in the Philippines. The CWS considered the 4.2-inch chemical mortar to be an ideal weapon for delivering gas, smoke, or high explosive shell in high concentrations in support of ground operations. 

CWTC Item 530, Standardization of High Explosive 4.2-Inch Chemical Mortar Shell, 4 Aug 42. (2) CWTC Item 571, same title, 29 Sep 42. 

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