In the military after the Civil War, the woman who performed the laundry duties were often as not wives of the enlisted personnel. In most instances they also did the laundry for the officers, unless an officer had a wife on post willing to do it for him.
If a post didn’t have sufficient enlisted men’s wives on post, then they’d have to contract out, or detail enlisted personnel to do the chore. The second option would be the most likely. The military back then spent money very grudgingly. (Even in the 1870’s they were still issuing hard tack made during the Civil War...)
In the field, all bets were off and the men, officers included became pretty “gamy” unless camped by sufficient water.
General Joseph Hooker had camp followers who took care of various things.