El Mahdi
Muad'Dib of the Anauroch
Field-grade officers do not belong to a branch, it is entirely based on rank. A colonel (field-grade officer) can serve in an administrative branch.
Yes, I do understand that officers of any grade do not exclusively belong to any specific branch. I think after 21 years in the Air Foce, I probably have that one down, but thanks for the refresher.

I however did make a minor mistake in that I meant company grade officers, and was trying to single out Army and Marine company grade officers as having combat training and most of them being in command of combat units, as opposed to Air Force company grade officers who likely have significantly less combat skills than those they command. Most officers in the Air Force, other than pilots and a very few other careers, are almost exclusively administrative only. Their college degrees, backgrounds, and their jobs are almost entirely managerial. Take for example an Air Force Maintenance Officer (usually a Captain, but sometimes a 1st Lt.). A Maintenance Officer doesn't require an engineering degree, or a science degree, or any other such thing. What they typically have is a management degree, and typically don't know a single thing about aircraft. I would imagine that Naval junior officers are similar to the Air Force in this way (lack of a combat background), though they at least have the chance to progress to command of a vessel and higher. It's not an absolute, but the majority of Air Force officers above the rank of Colonel are almost exclusively Pilots. Not being a Pilot in the Air Force can severely limit an Air Force officers career progression potential. Whether an Army or Marine company grade officer is in charge of an administrative unit or not, they still have more combat skill than an Air Force company grade officer.
But, I said it was a minor mistake because I would imagine that Army and Marine field grade officers, having once been company grade officers themselves, also likely have a significantly greater amount of combat skills than Air Force field grade officers (as again, most of them have purely administrative backgrounds).
