I know he's not really military, but since he is with his older brother Edward Elric, who is a state alchemist, I had to talk about this lovable main character.
Alphonse Elric, younger brother to Edward Elric, is an alchemist as well. He has always followed his brother and has pretty much helps him as much as he can while he is on his missions. So in a way, he does help the military, being beside his brother. He is very kind and caring, unlike the more immature Edward. But that doesn't mean Alphonse can't be, for he has his faults as well. That and his love for kitty cats by stuffing them in his suit of armor :3
At first he wanted to join the military as well with his brother, but because no one knows that they had committed a taboo, Roy Mustang told them that Alphonse couldn't. Alphonse is as smart as his brother but he does have the problem with being too kind. It really shows in some of the episodes how he is blind to the obvious or is dense, but then again, he is a year younger. That and when you think about it: When they committed the taboo thats when his soul was put in the armor. So when he's probably say 14 he really is probably 10 or 9 ( can't remember the date when he committed the human transmutation with his brother)
Sometimes he does talk to others that are in the military like Hawkeye. And it seems the other subordinates are fine with Alphonse around, so you can see that he is slightly known in the military. He will stick by his brother though in hopes to find the philospher stone.
Here is spoiler.... So eep! o.o Don't look unless you like to be spoiled:
Alphonse also talks to ex-military people, or Greeds comrades who were turned into chimeras. They have a side that tell about the military even deeper which helps the Elrics later on, especially finding out about the Furher being a homunculi. Even in the manga he talks to them and can see some affection that some others can't. Even though he isn't in the military, it does give him some previlages to do things that Edward cannot.
Though, the movie is sad for how he tries to see his brother again. Close to the ending Mustang holds him back so he doesn't go off to get his brother Edward, but of course I'm not gonna say the complete ending. I don't want to spoil it too much. But you can see how he still knows the military and helps them as much as they can, even when he is a human.
Alphonse Elric. Even if he is a soul trapped into an armor, he still has a great heart that steals all of ours to love him.