As you drive westbound across the rolling hills of Interstate 70 near Junction City, Kansas, the highway descends and you are soon presented with an impressive view of the concrete staging areas and flight apron of Marshall Army Airfield. If you exit at Ft. Riley and travel to the south side of I-70, you can park your vehicle and hike up a short, but steep, trail to the top of a ridge where the Atomic Cannon sits.
Correctly known as the M65 Atomic Cannon, this piece could launch a 280mm artillery shell tipped with a W9 nuclear warhead as far as 20 miles. The W9 had a yield of 15 kilotons and was, therefore, similar in strength to the “Little Boy” bomb dropped on Hiroshima. The M65 conducted the first and only live fire test of a nuclear artillery projectile on May 25, 1953 at Frenchman Flat in the Nevada Test Site. The test, codenamed Grable, was part of Operation Upshot-Knothole and was intended to train troops in nuclear battlefield operations.
An estimated 20 M65s were built and ultimately deployed to Western Europe and South Korea. They were retired by the early 1960s and replaced by more modern howitzers and ballistic missiles.
Photo and video courtesy of National Nuclear Security Administration / Nevada Site Office