First of all, he was a soldier, not a Marine. There is a difference. The Army has soldiers and the Marine Corps has Marines. Second, when talking or writing about Marines, Marine is capitalized, as it is a proper noun. Without a doubt, you were never in the Marine Corps, but I was, and I know the difference. Please be more respectful of us in the future. Once a Marine, always a Marine. Semper Fidelis.
My bad on the first. I should have known he was Army.
That being said, I intentionally left it lower case, as a true Marine would never desert his post.