Thanks to the beginning of the Cold War, weapons and military equipment in the fifties of the last century developed in accordance with the Olympic motto: faster, higher, stronger. Airplanes began to fly faster and further, bombs began to destroy targets over large areas, and artillery began to hit much further. In the case of artillery, the plus in the form of an increase in the firing range led to a number of disadvantages. More gunpowder was required to send the projectile over a greater distance. This required an increase in the caliber of the projectile and, as a result, the mass and size of the entire gun. As a result, the increase in the combat performance of the gun negatively affected its mobility. This unpleasant pattern did not suit many military personnel, including the command of the US Marine Corps.
In order to provide the KMP artillerymen with a light and powerful weapon, the command of this kind of troops in the mid-fifties initiated the development of a new artillery system. The caliber of the new gun was supposed to be 115 millimeters. The full weight of the gun had to be laid at three thousand pounds (about 1350 kilograms). In addition, the military wanted a high rate of fire. Unfortunately, there is not as much information about the project as we would like, so it was not possible to establish exactly where it was created and who was the chief designer. The gunsmiths solved the task set before them in a very original way. The name of the project was treated in the same original way. It was designated as XM70 MORITZER (MORtar & howITZER - mortar and howitzer). As is clear from the decoding of the name, the designers decided to combine a light howitzer and a solid-caliber mortar in one gun.
A new carriage was developed especially for the Moritzer. Unlike those available at that time, the brackets for mounting the gun itself were spaced apart and that's why. The customer demanded a rate of fire. For this, it was proposed to equip the XM70 with ammunition magazines. Two drums for three rounds each were placed on the sides of the barrel, which led to an increase in the width of the breech of the "mortar-howitzer". At the bottom of the gun carriage there was a base plate similar to the one installed on mortars. The barrel, magazines and recoil devices were attached to a special frame, which was installed on the carriage. To reduce the impact of recoil on the design of the latter, there were two hydraulic recoil brakes and one hydropneumatic cylinder to return the gun to the forward position. It should be noted that the magazines for the shells were used for a reason. The designers managed to fit the most real automatic reloading into the contours of the mounting frame. Its action was based on the recoil of the barrel. Thus, the XM70 gun could send all its ammunition towards the enemy in a matter of seconds. A very useful opportunity for "firing sorties" with a quick entry and exit from it. We should also dwell on the barrel design. Responsible persons from the Marine Corps proposed to develop a new active-rocket projectile for the new weapon. When fired, this type of ammunition does not require a high explosive power from the powder mixture. As a result, engineers were able to fit a thinner barrel on the XM70. In addition, the lower power of the powder in the projectile reduced the recoil, which made it possible to lighten the design to those same three thousand pounds.
By 1959, the prototype gun was ready. Soon, six more copies were built, which were used in trials. The use of a revolutionary new system for American artillery immediately demonstrated its feasibility in terms of combat characteristics. Thanks to the possibility of vertical guidance in the range from -6 ° to + 75 °, it was possible to "throw" a standard 115-millimeter blank weighing about 20 kilograms for nine kilometers. The new active-rocket projectile flew 16 kilometers. For a relatively small and light gun, this was just fine. Finally, two magazines for three shells each, together with automatic equipment, provided an insane rate of fire for a 115-mm gun. Both stores were emptied in 2.5-3 seconds.
The test results clearly spoke in favor of the XM70 MORITZER gun. But he had more than just combat performance. As it turned out, the manufacture of one such artillery system was one and a half to two times more expensive than assembling existing howitzers or mortars of a similar caliber. And the active-rocket projectile was far from cheap. In addition, a specific weight problem arose. The available guns were relatively heavy, but fired relatively light rounds. In the case of the XM70, everything was the other way around - heavy shells were “attached” to the light gun. Logistically, there was almost no difference between the Moritzer and the old guns. The last problem with the XM70 concerned the projectile. The beginning of the operation of its own engine of the active-rocket projectile was in the hands of the enemy - the flash and puffs of smoke perfectly betrayed the position of the gunners. The advantages of MORITZER could not outweigh its disadvantages. All seven samples produced were distributed to warehouses and museums.
Simultaneously with the start of testing the XM70, design work was launched to create a similar weapon of a smaller caliber. Having already received complaints about the cost of MORITZER, the gunsmiths decided to build a second weapon from the existing assemblies and components. As a basis for the M98 HOWTAR gun (HOWitzer & morTAR - howitzer and mortar), they took the good old carriage from the 75 mm M116 howitzer (post-war designation of the M1 gun). On it, with almost no design changes, the barrel was installed from the 107-mm M30 mortar. Despite the almost complete absence of specially made lightweight parts, the resulting Hawtar weighed only 585 kilograms. For comparison, the weight of the M116 howitzer was 650 kg, and the M30 mortar pulled "only" 305 kg. These 585 kilograms were able to fit the gun carriage, barrel and recoil devices. The M98 gun did not have a store - loading from the muzzle simply did not allow putting any automation.
At the end of 1960, the M98 HOWTAR gun went for testing. In this case, the situation was much worse than with the XM70. A number of design features of the "mortar howitzer" did not improve the characteristics of the original systems at all. On the contrary, the maximum firing range decreased from 6,800 meters to 5,500 meters. The rate of fire remained the same - a trained crew produced up to 16-18 rounds per minute. In terms of ease of use, the HOWTAR gun did not have any special advantages over the M116 or M30. This project was also closed, and all built samples were sent for storage.
Subsequently, the Americans tried to return to the idea of combining the positive aspects of mortars and howitzers with their previous goals. However, the newer XM193 project with a rifled howitzer barrel and a lightweight gun carriage could not prove itself in the best way. As a result, the Marine Corps and the US Army are still using "traditional" mortars and howitzers.
