> is the military hardened against deserters, starving soldiers, starving military families, and so forth caused by civilian infrastructure collapse? I doubt it.

That's where Article 90 of the UCMJ comes into play,

    Any person subject to this chapter who willfully disobeys a lawful command of that person’s superior commissioned officer shall be punished—

      (1) if the offense is committed in time of war, by death or such other punishment as a court-martial may direct; and
      (2) if the offense is committed at any other time, by such punishment, other than death, as a court-martial may direct.