Note to copywriters working for the DoD, or trying to appeal to a military audience: "soldier," "sailor," and "airman" are not proper nouns. "Marine" is a proper noun, because it happens to be part of the name of the service, United States Marine Corps. (Or, for that matter, the Royal Marine Corps on which the US version was modeled.) This does not mean that Marines are any more special or heroic or elite than members of the other services. (Marines, of course, will disagree, but that's part of their shtick. The rest of us just smile and nod.) It's an accident of language, no more.
Also not proper nouns: "military" and "veteran." Capitalizing any of these words, when they do not appear at the beginning of a sentence, does not emphasize how Special and Heroic and Elite our Brave Fighting Men And Women are for Making Sacrifices to Defend Our Freedom. It just makes you look illiterate. Now, you may not particularly care about literacy -- you're in the advertising business, after all -- but by God and the Constitution, I fought specially and heroically and elitely to defend your right to speak freely, not to sound like a moron doing so!
Thank You, and Have A Nice Day.