Re: Military Campaign
I think you might want to think about a Special Forces unit rather than infantry as you'll have a greater scope for scenarios.
Perhaps even, a Rainbow unit drawing forces from all over the place to counter a threat be that terrorism, Aliens, the Chinese or whoever you have planned as the bad guys.
That way you can have a bit more variety. Spetsnaz, Seal team, SAS, Gurkha etc.
After that you'll want to make sure they each have their own schtick. Sniper, frogman, heavy weapons, medic, radioman etc.
Points-wise if you do decide to go the Special Forces route I'd reccomend a higher point total. 100 + 100.
They're are loads of ex-Army/ Navy guys who can help with specifics if need be.