The XM123 is an experimental weapon that mated an auxiliary propulsion engine to a standard 155MM medium towed howitzer. Three prototypes underwent extensive testing at Rock Island Arsenal's Research and Development Division in 1961. The U.S. Army accepted the design in 1962. The weapon displayed at Memorial Field is serial number 1.The Selected Mobile HowitzerThe XM123 is a modification of the M114 155MM medium towed howitzer, also produced at Rock Island Arsenal. The XM123 was an auxiliary powered design that added an engine to the howitzer carriage to allow it to become more mobile in a limited capacity. This allowed for better defensive measures, better target acquisition, and less time to correct firing positions after fire. The XM123 base model included two 20-horsepower engines, while the XM123A1 variant included a single engine.Extra weight on the rear of the howitzer caused the barrel to become misaligned, and as a result the overall project was terminated. However, the M123 was produced in limited quantities using the twin engine design. None of these units were ever used.The XM123 was one of many experiments to add auxiliary propulsion to a normally towed howitzer. Other proposals included the XM124 and the Terra Star, both of which were also manufactured at Rock Island Arsenal. The XM124 utilized a smaller 105MM barrel, while the Terra Star utilized the 105MM barrel coupled with a tri-star wheel configuration.Changes in the needs of the U.S. Army led to the eventual termination of these programs; as a result, most of the auxiliary powered howitzers were never produced. Most howitzers that were produced were destroyed.