240mm Caterpillar Mark IV Self-Propelled Howitzer (SPH)
The 240mm Caterpillar Self-Propelled Gun concept never materialized for the United States Army before the end of World War 2.
Authored By JR Potts, AUS 173d AB; Content ©www.MilitaryFactory.com
During World War 1, United States Army authorities came to the conclusion that towed artillery was consistent with their current battlefield doctrine. However, large howitzers and like-artillery systems required multiple "mover" vehicles (either tractors or large trucks) to transport and much time was needed by the operating crew for the preparation of such weapons, in a sense defeating much of its tactical value. Making the artillery system self-propelled was the primary solution as less crew and time would be needed to transport and set up a firing position for the gun. The Caterpillar Mk IV was such a machine, born as a single pilot vehicle designed to propel a large-caliber 240mm howitzer.
The 240mm, 9.5-inch M1918 Schneider howitzer of French origins was the largest-caliber field gun to be deployed by US Army field artillery in World War 1 and was used to great success. The gun began life as a towed artillery piece originally designed during World War 1 and since having been updated on many occasions in increase potency and keep the type modernized for current battlefield requirements. The 9.5-inch barrel fired a hefty 356-pound shell which was propelled by a 49-pound bag of TNT and could reach out to 14,000 yards - approximately 10 miles - when fired.
The M1918 gun was towed in separate major components by no fewer than six tractors and required a full 20-man crew to transport, setup and operate. In a combat situation, the crew would have to set up the gun system in the cover of darkness, which also required reconnaissance of the ground and much training as deployment of the six tractors and the many required hours needed to set up the gun in broad day light would have drawn much attention from enemy artillery. When the precise firing position was found, a seven-man lead crew was first on the scene to layout the emplacement pit using a surveyor's transit. The crew then dug a 7x6x3 foot pit with conventional picks and shovels over the course of three hours if the ground proved fair. An additional twelve hours and the balance of the 20-man crew was needed to complete setup of the gun.