M2 4.2 Inch Mortar - History

History

The first 4.2-inch mortar in U.S. service was introduced in 1928 and was designated the M1. Development began in 1924 from the British 4-inch (102 mm) Mk I smooth-bore mortar. The addition of rifling increased the caliber to 4.2-inch. The M1 fired chemical shells to a range of 2,195 meters. Upon the entry of the United States into World War II, the U.S. Army decided to develop a high explosive round for the mortar so that it could be used in a fragmentation role against enemy personnel. In order to extend the range to 2,926 meters, more propellant charge was used and parts of the mortar were strengthened. Eventually, the range of the mortar was extended to 4,023 meters. The modified mortar was designated the M2. The M2 was first used in the Sicilian Campaign, where some 35,000 rounds of ammunition were fired from the new weapon. Subsequently, the mortar proved to be an especially useful weapon in areas of rough terrain such as mountains and jungle, into which artillery pieces could not be moved. The M2 was gradually replaced in U.S. service from 1951 by the M30 mortar.

Starting in December 1942, the US Army experimented with self-propelled 4.2-inch mortar carriers. Two pilots vehicles based on the M3A1 halftrack were built, designated 4.2 inch Mortar Carriers T21 and T21E1. The program was cancelled in 1945.