Developed in the early 1950s, the Honest John was the U.S. Army's primary field artillery rocket until the mid-1970s. A mobile tactical system, the free-flight, fin-stabilized, surface-to-surface rocket carried a nuclear or high-explosive warhead. A handling beam was temporarily attached to the rocket to load it on the truck-mounted, rail-type launcher. Rock Island Arsenal was responsible for the design, development, and manufacture of the Honest John's M386 launcher.The First of Its KindFirst tested by the U.S. Army in the 1950s, the MGR-1 (Medium Guided Rocket) Honest John was the first rocket capable of carrying an atomic payload. The rocket itself was designated XM31 during the testing phase, with the X being dropped when the rocket entered its main production sequence and service in 1953.The Honest John system was designed to fulfill multiple roles on the battlefield. The payload bay was capable of carrying a high-explosive warhead, a cluster bomb, or an atomic device. The high-explosive warhead weighed about 1,500 lbs. The W31 nuclear device was adjustable, having preset yields of 2, 10, or 30 kilotons of explosive power. The cluster bomb consisted of 356 M139 bomblets which were capable of delivering high concentrations of chemicals, such as Sarin nerve agent. The rockets were never equipped with chemical munitions in a live setting.The weapon system entered large-scale implementation among NATO nations in the late 1950s through the 1960s. By 1968, the larger MGB-1A variant had been phased out in favor of the slightly smaller, lighter and faster MGR-1B. Both variants were deployed across the U.S., Canada, West Germany, Greenland, South Korea and Norway. By the early 1970s, the U.S. began phasing out the Honest John in favor of the smaller and more powerful Lance rocket. By 1991, all U.S.-operated Honest John rockets were removed from the Army inventory.The Honest John remained in service until 1997, when the last system went offline in South Korea. Other operators had used the system until earlier in the 1990s.