Hypothetically, if a navy admiral had to wage a land war with ground forces, or an army general had to wage a war at sea with naval fleets (or they had to do an air force commander’s job or vice versa), how well would they fare?
Are most military officers largely knowledgeable of the other forms of warfare outside their own branch, kind of like how all doctors share a common baseline understanding of medicine due to pre-med?
(Don’t ask why they would be in such a situation) 
Senior officers typically get training in joint operations. Usually having had some experience in this sphere is necessary to even advance to the top ranks.
However the level where an officer might have control of assets of a different service, is one where he will not be involved in day to day running of operations. He’ll tell them what to do and leave it up to them on how to do it.
It will vary by country.
The whole purpose of the Spanish Armed Forces having a single Officers’ School is to have all officers train together; all officers get the same common core training, all get courses which are specific to each branch, and all have classmates across branches. The intent was to cut into inter-service rivalries and reduce misunderstandings; it seems to have worked.
Uh no. They’re supposed to share a common baseline understanding of medicine due to core courses. Most countries don’t even have pre-med, and in those countries which have such a thing not everybody who goes to medical school comes from pre-med (Chemistry and Biology were the next most-frequent Bachelor’s for the medical school in my American university when I was in grad school). Yet every doctor, not in a country but in the world, is supposed to share a common baseline knowledge.
I expect all of them can handle the administrative and logistics side of things equally (in)competently. I expect that Army, Navy or Marines, they can handle an air superiority campaign and understand air-to-ground operations or arty support.
That being said, I wonder to what extent the Navy or Air Force brass would handle a COIN operation or “win hearts & minds”. I’m not sure a Navy guy could read a land map in the best tactical sense (i.e. identifying key strategic control points, the key points to take to secure *those *points etc…). I’m not sure how a ground guy would deal with 4000 miles of flat, open sea in every direction either (but I’m chuckling at the idea of their ordering the establishment of floating FOBs everywhere).
I think various branches also impart different roles and responsibilities to each officer/NCO echelon and they’d have trouble breaking the mold they come from to leverage their new assignment’s guys efficiently and without running into politics and morale/branch culture problems ; and while delegating solves that to a point, the top brass can’t just give vague directives and tell people to “sort this shit out your way, you know what to do, figure out how to do it” any more than a civilian manager can. They need to know and understand what’s going on if they want to have any semblance of control.
Also, ultimately I think many would run into the same mentality issues as people who move from e.g. software development to sales to management to creative postings ; that is to say to tend to nurse the brain spiders inherited from their original post and see their new branch as “just support for Previous Branch operations, which are the most important ones”. Like an Army guy would see his brand new aircraft carrier group as floating air support for the grunts instead of a fully fledged force projection tool ; an Air Force guy would see his brand new tank brigade as a new and interesting asset to seize the other side’s air bases and SAM sites with, the better to let the “real force” do its job etc…
In the (mediocre) movie Dunkirk, there’s a scene where a senior Navy officer and a senior Army officer are talking about how to evacuate the soldiers on the beach.
The Navy guy says, for the largest ship “we’ll have to wait 8 hours, till the tide comes in”. The army guy says “I thought the tide changes in 4 hours”.
The Navy guy says “it’s a good thing you’re not in charge of the Navy.”
It’s a movie, but it illustrates a point about all management. If the senior guys at the top don’t have basic technical knowledge, they can create a disaster.
See, I learned a different lesson from that scene - about the importance of staff work. The army guy didn’t need to know what the navy guy knew, and vice versa, so long as they were working and communicating efficiently. You don’t have to be an expert on everything, so long as you have experts around and are willing to listen to them.
Of course, at some level, you have to have guys knowing their specialties. Even if an army general can figure out that it’d be good to have this ship over there, he probably has no idea how to steer the thing, so you’re going to need an actual sailor at the helm.
At a higher level, if a general were to be in command of a fleet, he’d probably give orders like “Proceed to this location, in standard formation”, and it wouldn’t matter if he didn’t know what the standard formation was, as long as the captains under him did. The trouble wouldn’t come until you got a situation where, for some reason, the standard formation wasn’t a good choice (and even there, the sea-wise subordinates might still point that out, at least if it’s a well-run organization).
Probably depends on just how senior. In the US, the Unified Combatant Commands are commanded by flag officers from any service. At that level, I suspect the job is a combination of grand strategy that’s above any one service, and politics/bureacratic stuff in terms of funding, supply, etc…
I think, but am not sure, that each one of those commanders has his own set of commanding officers under him for each service. So when he and the politicians decide to do something, he issues broad orders for say… a land attack to accomplish X, an air campaign to accomplish Y and Z, and for the Navy to accomplish task AA. He’s not likely to get into HOW his subordinates go about planning those things.
Have to agree with Bump. At a certain point you are so high in the stratosphere that strategic policy decisions are made jointly and one service commander can have authority over multiple component commands.
Speaking generally, (ha) one service’s members have little to no idea how the other services work. They share certain Joint Pubs, but these are so broad that they actually say very little about the nuts and bolts of war fighting. When I was in the Army, I had little clue how the other services worked. Heck, I barely knew what the guy in the next tent was up to because my own warfighting function occupied 100% of my attention.
The other inter-service training basically boils down to, “These are their capabilities and their responsibilities, so if you have a question dial your liaison officer.”
As a Staff Sergeant (E-6), I served in a “purple” (joint service) environment. Heck, it was technically a coalition operation, although I personally had no contact with foreign militaries.
I knew, in general terms, what the Air Force personnel I worked with did, largely because their desk was next to mine. They were technically seconded to the staff section I worked for, but operated almost entirely independently. If it came down to it, I’d have had no idea what to tell their enlisted members to do, other than, “Do what you normally do for the staff briefing.” Even at the general administrative level, I’d have had no real idea on what to do with them. I know they have different training requirements, pay and promotion policies, etc., but I wouldn’t know what they are or even where to look. I knew quite a bit about which Army Regulation or Field Manual to look in to answer questions about Army procedures, but I don’t even know the proper terms for Air Force equivalents.
I served with two Marines who were seconded to my staff section. For no apparent reason, the Special Security Officer billet, at a U.S. Army command, was specifically a USMC enlisted billet.:dubious: I could have supervised that position, since he wasn’t actually performing USMC-specific duties, but, again, I’d have had no idea about even pretty basic administrative / supervisory things (do Marines get NCOERs, for example?).
The other Marine was my supervisor for while - he served as my staff section’s Administrative NCOIC (Non-Commissioned Officer in Charge). That was an open billet - it got filled by personnel volunteering from other units, since the unit that ran the command wasn’t really staffed adequately for what it wound up doing (this was in 2005, when the U.S. Army started suffering a lot of recruiting and staffing issues). Anyway, as his subordinate, I had to give him a lot of on-the-job training about U.S. Army administrative policies and procedures, which was made even more fun by the fact that I wasn’t an admin specialist myself (again, staffing shortages), and only had OJT myself. It helped that he had served in joint commands before. So, at the level of Sergeant First Class / Gunnery Sergeant (E-7), for an admin post, there’s definitely some cross-compatibility, but if he had been on his own, he would have been pretty screwed.
There were also Navy and Coast Guard personnel, but I had only the vaguest idea of what they even did, and there’s no way I could have supervised any of them.
I imagine there’s a fair amount of overlap between some parts of some services- i.e. the Army and USMC probably overlap a fair amount in terms of at least operational level stuff and downward, with the Marines having specialized amphibious landing know-how. In WWII it wasn’t uncommon to have Pacific ground operations commanded by either Army or USMC generals, with units from both services underneath them. For example, in the Battle of Okinawa, the 10th Army was originally commanded by Gen. Buckner from the Army, but when he was killed, command turned over to USMC Gen. Geiger.
Similarly, I suspect that the prosecution of an air campaign is something that USN, USMC and USAF aviation officers would all know- the main USN/USMC difference is in the specialized procedures from operating off aircraft carriers, not in the actual tactics and objectives, etc…
But would an Army general know how to go about coordinating an air campaign? A Navy officer know how to mount a land offensive? Highly doubtful.
Broadly, this isn’t too far off the mark of how things are done today in the U.S. military. The commander of a combatant command has the overall war fighting responsibilities within a particular region (like the Pacific or Europe) or for a particular activity (like Special Operations or Transportation). Below him are other high ranking general and flag officers who are in charge of the components (Pacific Fleet or U.S. Air Forces Europe). The top dog is not a master of warfare in all domains (land, air, sea, space, cyber, special operations, etc).
Think of the CEO of a major corporation: they aren’t there because they are supposed to be the ultimate accountant, lawyers, salesman, HR guy, etc. who is in charge of coming up with all those strategies and operations on their own. They generally rely on hiring experts in those fields and applying leadership to point them in the right direction.
FWIW, there are some regulations or manuals that overlap multiple services. I’ve seen Regs that apply to both Army and Marine Corps, for example, but within the text there are certain pieces of terminology that don’t quite mean the same thing.
There are also a few regs that very definitely DO encompass all services. FM 2-22.3 must be the king of regulatory overlap, because it applies to not just the Army, or the DOD, but the entire Federal Government.
+2 to bump.
Current doctrine (thanks to the Goldwater-Nichols Act of '86) pretty much sets up the Unified Combatant Commands with Combatant Commanders (CCDRs) and their Staffs. The 4-Star CCDR has his functional staff of Air, Land, Maritime, and Space commanders which basically, as bump indicated, draw functional commanders from their respective Services. So the Combined Forces Air Component Commander (CFACC) at the UCC level would be an Air Force General Officer; the Combined Forces Land Component Commander (CFLCC) would be Army, and the Maritime Component Commander (CFMCC) would be Navy. Depending on the size of the Combined/Joint/Task Force, the officers might differ. Ultimately though, functions such as Air Sorties/Deconfliction falls to the Air Force, Artillery Fires deconfliction falls to the Army/Marine Corps (whoever owns* the battlespace), Maritime missions fall to the Navy (with air missions going up to the Air Force’s cell for deconfliction), etc. It can be a confusing web, but all you have to do is look up your regional Combatant Commander’s cell for a phone book listing of who does what.
For example, my last deployment, I was in an EOD regional Task Force as an Air Force EOD guy, working on a Navy Battalion staff, with two Army EOD Companies and and Air Force EOD Flight underneath that we supported. It just depends on the size and scope of the forces. We routinely called higher headquarters for airlift support through the Army’s coordination cell with the Air Force, and contacted the Marine Corps’ fire support cell for pre-planning fire missions (or finding out where not to be at certain times!).
But back to the OP: Once you get to the General/Flag Officer level in the United States, you have been through a few Joint schools. It’s not uncommon for Army/Air Force to go through the Naval War College. It’s possible for the Air Force to go through the Army War College. The Air Force hosts Air University courses for the other branches too. That being, General Officers are versed in the capabilities of the other branches, as well as their limitations. Those CCDRs are responsible for setting the overall strategy of a campaign within operational/political/economic constraints, and they delegate that strategy to the functional componentleadership to carry it out. As for us underlings, we can be plug and play in a ‘purple’ unit, but we’re far removed from the operational/political/economic constraints. We just have to learn the proper paperwork to fill out under the Joint Force we’re under, and which offices to call.
Tripler
Oh what a tangled-warfighting web we weave.
*Ownership: The CCDR can delegate regions to certain forces–I happened to be in Southern Afghanistan where 2MARDIV was the Ground Forces’ component, led by a Marine Corps 2-star General.