This was in a forgotten anthology I read maybe thirty years ago.
A new recruit on day one of his compulsory military service, he writes home telling his parents (mom) about some of the things such as a barber's tent with an actual striped pole outside where they all get their heads shaved, I think he then describes a greasy meal (not sure about that) but then he says he has to go on parade.
He is a bit confused about when he left home at the train station because his mother was sobbing hysterically and his trembling father was muttering something like "When I was a youngster a war was a real war, goddamn government"
They line up and 'Sergeant Grizzled Veteran' comes out and snarls at them about the four things a good soldier should be. He lists these as disciplined and ### and ### and dead.
He then outlines what he means by disciplined and the next two items, while he does this some trucks pull up beside the ranks.
Suddenly machine guns protrude from the trucks and a hail of bullets slaughter all the rookies.
Sergeant smiles sadistically and says "And that's what I mean by being dead"