The Adventures Of Private Olsen

With all his years in comics, young Jimmy Olsen, a healthy lad, must at one point served in the United States Armed Forces... 

...and he did, in Superman's Pal Jimmy Olsen #23 (September, 1957), under this cover by Curt Swan and Ray Burnley!

The Adventures Of Private Olsen

Here, in this tale by Otto Binder, Curt Swan and Ray Burnley, Jimmy goes on a story for the Daily Planet, to find out what it's like to be in the army, getting a little help from Superman and his friend, Colonel Otis.  Going undercover as Private Hudson, Sgt. Blye decides to make a little money off the boy, by betting he'd fail, but also hedging his bet by making everyone else think he's a general's son, who would be a natural soldier. 

 

Superman comes in to help Jimmy succeed, and even Sgt. Blye comes around at the end, as Jimmy nearly gets launched into space, looking for the bet money Blye had collected.  Jimmy decides army life isn't for him, and goes back to do his story for Perry White.