Nuclear artillery

Now take a look at this baby: this is a nuclear artillery cannon, blasting a couple of kilotons toward the commie enemy behind the next ridge, complete with badass lightning effects too. So why didn't this catch on? Why is it again that apart from this one test, atomic bombs are usually detonated remotely or after you drop them from a large altitude?

This photo is actually from a 1953 test in the Nevada desert called Operation Upshot-Knothole and what we see is the "Grable event", a 280mm cannon shooting a 15 kiloton payload. Yeah, the caption says "Hundreds of high ranking Armed Forces officers and members of Congress are present," I guess most of them would have rather skipped this event and the resulting "increased offsite radiation exposures."

Nevada Test Site - Operation Upshot-Knothole - 1953 - a set on Flickr