The book is an all time classic. It is even more Pro-Military than the movie. At the same time the ultimate Bug-Hunt story. Much better than the movie, a quick read and relatively short. Give it a try. Heinlein is one of the big three of Sci-Fi for a reason.
By the way military service wasn’t required for citizenship. There were some other civilian services that would earn you citizenship.
Jim
So said Heinlein later, but that’s contrary to what the book says. When the main character (Johnny? Or am I misremembering?) is filling out the form for jobs in the service, he lists a bunch of Navy jobs, then a bunch of Army jobs, with Mobile Infantry last on the list. He doesn’t bother listing anything else, because they’re all things like failure-testing spacesuits on Venus. Surely, if “postman” or “file clerk” were options, they’d have made it onto his list after (or even before) MI.
As for the specific story the OP is looking for, the closest I can come is Jack Handy: “I can picture a world without war, a world without violence. And I can picture us conquering that world, because they’d never expect it.”.
You might try reading John Brunner’s story What Friends are For in the collection Foreign Constellations. In that scenario, children who display violent tendencies are assigned a genetically engineered alien called a “Friend” who follows them everywhere and forces them to become meek and polite. It has a twist ending, but different from the twist ending that you describe.
Not much of a trick, really, as the movie was pretty anti-military. It’s a satire of the characters and attitudes it portrays, not an endorsement.
Yes, Okay, but if you went and saw it with 3 old friends that all collect comic books and never read the book, that subtlety would be overlooked.
Jim