"Devil Dog" is what jar heads (Soldiers in the U.S. Marine Corps) affectionately refer to themselves as. Spelled backwards, Devil Dog spells "God Lived." I am not sure if this is intentional, and if it is what the hell it has to do with being a Marine, but as it is unlikely that any U.S. Marine is able to read the words "Devil Dog" forward without refering to the picture of the little red dog next to those words in his field manual, I would imagine it is a coincidence.