I was in a similar situation. I was 33 (34 now) in a totally non-medical profession, holding a B.S. degree and a 2.8 GPA. Let's just say I'm a little more focused and goal-oriented now than I was when I was 18!
I did exactly what "bigwavedave" suggests to you. I took all my prereqs at a CC, kicked butt and managed a 4.0 with those. This definitely shows admissions people that you've "grown" a bit.
I'm now in an accelerated B.S.N. program (which is also an option for you if you have a bachelors already). I have one semester left and, unless my life falls apart before finals in two weeks, I should still be maintaining my 4.0.
Re: your Army training, I'm sure it will be a bonus to your consideration. Oh, and by the way, when I contacted the university I'm currently attending, they also told me my 2.9 undergrad GPA was discouraging. However....when they ran the GPA for prereqs, then there was no problem. So, if you can figure out and slide in your "new" applicable prereq GPA (all the math, science, english, etc. that they want for admission) this may help also. I was able to show that, not only were recent prereq grades at a 4.0, but that the "old" classes that mattered (i.e. math, english, chemistry) were all great grades also. It put a different spin on the picture and suddenly the fact that I got D's in classes like "Music Theory for Non-Majors" 15 years ago was not such a big deal.
Furthermore, I'd suggest going in and talking to the dean of academics in the nursing school...or someone similar. Set an appointment and go visit -- now they know your face, know your name and know you are (hopefully...ha ha) an articulate, intelligent person and not just a piece of paper with a 2.6 GPA.
I wish you the very best of luck!! PM me if you have any questions.