280MM Atomic Rifle (Grable Event, Upshot-Knothole Operation)

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Unclassified FACT SHEET 280MM ATOMIC RIF IE Ch May 25, 1953, a test of the Army’s new 280mni gvin firing an atomic pro jectile was held at the Nevada Proving Grounds under direction of the Department of Defense and the Atomic Energy Commission. Congressional observers, military staff officers and approximately 2,500 participating troops witnessed the first test of this nuclear projectile. After several conventional shells were fired, the nuclear projectile was set off. The tremendous power and energy released’ by the atomic explosion dwarfed the sound and pov/er of conventional shells. The troops were in trenches approximately 5,000 yards from Ground Zero. The nuclear shell was prepared by specially trained Army technicians, with Atomic Energy Commission scientists cooperating. The gun crews then loaded the weapon and retired to revetments. The charge was then set off by electrical means from the main Control Point of the Proving Grounds, with the shell bursting approximately 500 feet above Ground Zero. At its firing, the gun was pointed NNE towards its target approximately 7-8 miles away, on Frenchman Flat, from the top of a small knoll. Among numerous items exposed to the blast of the nuclear explosion were railroad cars, including an obsolete Diesel engine, all of the type used by the Army Transportation Corp. Numerous other items of military hardware were used in the test. Trees brought in from nearby mountains were exposed. All of these items, after complete examination and evaluation of the effects, will provide valuable information for our military forces. Rabbits, mice and pigs were used during the test to gather vital bio-medical Air Force participation included two QF-80 pilotless drone planes for gather ing of radiation effects data. Also forty or more aircraft performed other missions such as cloud sampling, and tracking, air crew indoctrination and others carried many cameras to provide airborne photographic studies for future research. Both military and civilian technicians of the Arny Artillery Branch were present to see first hand the results of nvaqy hours of research on this new Congressional members were able to see, from their observation post 7-8 miles from Ground Zero, the effects of the blast on the targets. They went into the forward area v/hen radiological safety permitted. They also saw the partici pating troops as they left their trenches minutes after the blast and moved forward in a simulated combat maneuver. —more— BEST COPY AVAILABLE

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Participating troops came from all Army areas within the continental limits of the United States. They were formed into two composite Battalion Combat Teams to take part in the exercise. Troops representing First Army came from Fort Totten and Fort Jay, New York. The Second Arngr area was represented by personnel from Camp Pickett, Virginia, and Fort Mead, Maryland. Third Army sent personnel from Fort Jackson, North Carolina, Fort Benning, Georgia, and Fort Bragg, North Carolina. Fourth Array area troops v/ere from Camp Chaffee, Arkansas, Camp Polk, Louisiana, Fort Bliss, Texas, Fort Hood, Texas, and Fort Sill, Oklahoma. From the Fifth Army area personnel from the following installations attended: Camp Atterbury, Indiana, Fort Leonard Wood, Missouri, Camp Carson, Colorado, Fort Sheridan, Illinois, and Fort Riley, Kansas. The Sixth Army area sent troops from Fort Grd, Fort McArthur and the Preside of San Francisco, all in California. The 85-ton gun has a range of approximately 20 miles and is more accurate at long ranges than any mobile artillery piece now in use. In ballistics tests at Fort Sill on March 26, 1953, the shell was fired for a distance of approximately seven miles. Shells used in the Fort Sill tests v/eighed The crew which manned the gun for the test underwent intensive training with the cannon at Fort Sill, Oklahoma. These men are members of the Army’s $2nd Field Artillery Group. On October 15, 1952, at the Aberdeen Proving Ground, Maryland, the Array first publicly demonstrated the 280mm cannon. This public unveiling followed eight years of research and development. In 19UU, the Army took initial steps to develop a heavy artillery piece that would be superior to artillery weapons of World War II. In 19U8, the Army experts teamed with civilian scientists and engineers of the Franklin Institute of Philadelphia to design the gun. Work began on a pilot model a short time later. In 19U9, it was determined that it would be practicable to produce atomic projectiles which could be fired from a large caliber weapon. As a result the gun was redesigned in certain respects to accommodate such a projectile. In 1951 the first unit was completed and ready for initial non-nuclear tests.