There are 1.4mm active duty personnel right now and according to
this, less than half actually cast a ballot. While the officer corps tends to be conservative and Republican, the enlisted force is much less so. I know GW was boosted in 2000 by the military absentee votes but that vote was obviously ridiculously close where every vote really did count.
Far be it from me to discount their vote, but I'm not sure their vote is as important as you are letting on.
Suppose it was. Would calling Russia a foe excite them? I mean, the Cold War is over. How many active servicemen even remember it?
Nobody I work with was excited about it.

Romney isn't going to generate the same type of support GW did and that mostly has to do with GW's daddy being a war hero and a Reagan man made him someone who was beloved by that generation of the military.
One of the problems with America right now is that less than 1% of the population is serving or have someone they are related to that is serving. Less than 8% have served and that number is falling fast with all the WWII guys dieing off. America has no idea what the hell their military does half the time, some posts on this board over the years have proven that to me. People don't even want to take the time to find out, politicians are part of that group to a degree. With Obama he at least had a constituency that worked in the active duty military before he became president, all Romney has is probably guard/reserve knowledge in a very light military infrastructure state (Mass).
Santorum is probably better off with his knowledge of the military as his time as a Pennsylvania senator but like Romney, he was working in a state with no large military installations. He does have War on Terror experience though, that might play well to military voters at some point.
You know who is widely popular among military folks? Moreso than the general population IMO? Ron Paul, they love them some Ron Paul. I don't go a day without hearing about him, but I can't get behind him because I completely disagree with his stance on foreign affairs. Outside the economy, that is my #1 issue.