Let’s face it… a gun that shoots a nuclear shell = AWESOME.
The M65 280mm “atomic cannon” was an early 1950’s weapon designed for a single purpose: to lob 15 kiloton nuclear shells at invading Soviet forces in Germany. It was kind of a doomed concept… it was a massive piece of equipment that, while technically mobile, would in practice have been a largely fixed emplacement. Range was good by cannon standards, but terrible by “bomb carried by an airplane” standards, which is why it went away in only a few years.
It fired a live nuclear shell a grand total of once, the Upshot-Knothole-Grable test of May 25, 1953, producing some of the most impressive and iconic images from the nuclear weapons race. The shell was a gun-type bomb, similar in concept to the Little Boy bomb. This was used because the bomb was narrower in diameter than an equivalent implosion device (importance since it had to fit in an 11-inch diameter cannon shell), but it resulted in a lower performing explosive than if it were an implosion device.
Drawing of a smaller gun-type nuclear artillery shell via, of all things, Greenpeace. Apparently they got their mitts on a British nuclear weapon manual some time back, and decided that the thing to do to help prevent nuclear proliferation was to post bits of it online. Thanks!
This image from the Los Alamos National Lab webpage may technically not be all that impressive, but the appearance of apparently normal “stuff,” namely the power pole, lines and transformers, gives the image a creepy vibe often missing from shots of nuclear explosions.
This page HERE has a number of good photos of the cannon and its tractors, as well as selling a good PDF of AutoCAD layout drawings of the beast.