There is mention of some kind of Grand Mutiny in Fort Lewis at least, it is only mentioned by Thurston's wife (along with starvation and plague). I think for the most part it seems that most of the military's forces that survived either headed to Boise with Thurston or were incorporated into Yakima.
That's in company with Stirling's Word of God that most of the troops marched into the cities and died/scattered when things finally collapsed.
In some cases, I buy this. In most others...not. If a large unit (usually the top echelon at whatever base, so I Corps at Lewis) survives the first 24 hours (with half its leadership slots unfilled, due to MIA/KIAs from the Change)....I doubt they will have much problem hanging together. The main leadership challenges would be in that first day, as surviving/in-contact officers assume authority in the empty slots.
Given that the "facts" of the Change (and their long-term implications) would be obvious to a military post within a few hours (SF units and the Ranger Battalion at Lewis have small unit live-fire exercises at all hours, so I Corps would know about both firearms and internal combustion engines no longer working, and they'd know it wasn't EMP)...nobody would send troops into the Seattle-Tacoma metroplex. Leaders wouldn't throw troops into unwinnable situations to make a gesture at saving people who obviously can't be saved. The command would transition straight to "preserve the Unit" mode, and act accordingly.
<Stirling simply says* that "I assume that the military would stay true to their oaths, and so die in the cities".....but then, they have to do that, or Norman's PPA would be significantly less of a threat to the Meeting States. IOW, it's authorial handwaving.>
I'm not at all joking when I say that I Corps (in a much-reduced form) and their dependents would be moving out of Ft. Lewis by the end of the first week. My guess is west, to the Olympic Peninsula (which has the requisite fishing and agriculture to support a population).
Places like, say, Edwards AFB or Ft. Benning.....yeah, they are just in a bad position. Most of the Navy/Marine bases aren't well-situated, either. Most of the military would perish or scatter, that's true enough. There are, however, a handful of major bases where (absent reaaaaaallll bad luck or total incompetence) you could expect large units to survive (even if they had to relocate) the first year.
Ft. Bragg and Ft. Jackson.....maybe. I am, for the Record, less than convinced that North Carolina would be a true Death Zone. There's a lot of towns and small cities that both have access to decent food supplies and are out of the natural path of the Death Plumes from the denser areas.
I'd fully expect the military to come out on top of the survivors in Hawaii. Especially on Oahu (where >90% of the population would die, so you can expect the survivors to be pretty bloody) and the Big Island.
Given the sheer number of odd bastards wielding Commissions, you can also expect the societies developing out of these military-dominated survivor clusters to range from "1950's America, with extra Fascism", to stuff that Norman would approve of, on down to truly weird things. Contrary to what a lot of fanfic writers seem to think.
*-to quote Stirling himself: "Basically, not many of the American military in the Emberverse survive because I assumed that they'd take their duty and their oaths very seriously indeed.
The downside of this is that it means trying to save large numbers of people who simply cannot be saved; they're attempting the impossible. The metropolitan centers are a problem without a solution."