The XM124E2 is an experimental weapon that fitted an auxiliary propulsion engine to a standard light towed howitzer. The adaptation was to provide built-in mobility. The XM124E2 was an unsuccessful experimental project of Rock Island Arsenal's Research and Development Division from 1962 to 1965. The weapon displayed at Memorial Field is serial number 3.

The Self-Mobilizing Howitzer

Using the M101 Howitzer as the foundation for its design, the XM124E2 was the third prototype for the XM124 family. The concept was to develop a howitzer that was able to self-correct without needing a secondary prime mover to adjust its position. The XM124 provided between one- and 22-horsepower engines to drive the carriage. The engines were air cooled, and the motion of the carriage was controlled through electric steering.

The goal of the engines was not to consistently drive the howitzer from point A to point B, but rather to allow it to move small distances to correct its firing position, move into a better defensive position, or to provide a larger range of fire. The XM124 testing took place ahead of the M2A2 Terra Star testing that utilized a tri-star wheel concept in addition to self-propulsion.

The project ran from 1962 through 1965, when the project was cancelled due to lack of need for the weapon design.

The XM124E2 at Rock Island Arsenal is the only E2 prototype, having a single 20-horsepower engine and a lighter weight carriage for better mobility and better efficiency.