A piece of pure 1950s early Cold War madness. The cannon was originally developed to fire conventional warheads but someone must have decided that the best way to halt, or at least slow, the hordes of Russian tanks that were expected to roll into West Germany was to toss low yield nukes at them. It wouldn’t matter how much the area was contaminated, at least it wouldn’t be Commie, dammit.
There’s a part of me that would like to write a technothriller style tale of a conflict involving some of the madder weapons from the Cold War era. These guns, Vulcan bombers, Ekranoplan etc. Of course, the hard part would be resisting the urge to romanticise all that awesome tech and ignore the rather horrible effects of its use.