personalities are the major factor in too many cases. The bad thing is that the major and obvious personalities may be almost peripheral. Staffs tend to be quite loyal to their bosses and can sway things. There is also the impact of inter service relationships. Both those things can have a more than significant effect.

Look at my favorite unnecessary battle, Peleliu. Nimitz ignored both Halsey and Spruance who argued it was totally unnecessary to accede to MacArthur who thought otherwise and he did so as much because he and Ernie King had stolen a lot of resources from MacArthur for over two years to build up the Pacific Theater to the detriment of MacArthur's SouWesPac Theater and Nimitz believed he owed MacArthur a bone or two. So the 1 MarDiv went in to make unnecessary history at great cost. So, Ernie King had an impact as did inter service relationships. MacArthur's direct line to DC probably contributed to the decision.

To re-emphasize John's Somalia example (I'm sure he knows far more than I do so he can correct me if my interpretation of what I've read and been told is off the mark). I'd put the mess down to four major items. First, TF Ranger repeated the same TTP over and over -- they became too predictable. Second, the lack of unity of command that John cites. Third, CentCom, as a result of having had Norm Schwarzkopf as CinC had learned to micromanage and they did that (to no positive effect I can discern). However, I think the most significant problem was Jonathan Howe, Adm, USN (Ret), former Bush 41 NSA and Clinton NSC staffer turned UN lead in Somalia (at the behest of Clinton); that and Bill's rather foolish eruption an order to "get Aidid..." which Howe ordered carried out over the objections of several. Thus, Centcom tried to act IAW the personality of their former Stormin' Commander and there's that direct line to DC again -- and this time wielded by a guy who wasn't nearly as smart as Douglas.

Turning to Viet Nam, it's no secret that Westmoreland and his staff did not get along at all well with III MAF -- and I'd suggest anyone who couldn't get along with Lew Walt has some problems -- or with FMF Pac. The FMF Pac CG from 62 to 64 was Brute Krulak. He made as lot of trips to VN and talked to Westmoreland on most of them. To little avail. Against the advice of his staff, Westmoreland did let the Marine CAP program continue and later grudgingly admitted it was 'ingenious.' It wasn't as great as some say but it did work and it was vastly better than anything the Army did much before mid-1968.

There weren't that many commands inside MACV, it was pretty much a book Joint Staff. Momyer, the 7th AF Cdr fought continual turf battles with the Army, Navy and the Marines and the SOF community had its moments of rebellion but by and large, there were no strategic problems in VN. In the SEA area, as John notes, there were big problems due to the disconnects and the fact that MACV would sometimes overflow the boundaries a bit. Laos was a separate story unto itself, of course. Thus, in effect there was no Operational problem, VN was the operational entity for MACV and the strategy had put them there. VN was virtually an annoying sideshow and resource drainer for PaCom (who had little or no Operational play in that theater), much as Afghanistan and Iraq are to CentCom today.

Westmoreland was not a strong leader but he did have a strong staff * . They fought III MAF to a standstill, talked to McNamara and Johnson's folks constantly, cutting their bosses nominal boss CincPac (Harry Felt until 64 and U.S. Grant Sharp from 64 until 68) out of the loop -- much as MacArthur's folks had done in WW II. So the personalities of Johnson, McNamara, the two Admirals and a far from pushy Westmoreland intertwined to produce a Staff-run war with a direct WH/E-Ring to Saigon interchange. Add to that the facts that PaCom is so big that micromanaging is difficult if not impossible and it had never learned to do that as a result of having Nimitz and a series of Admirals in charge. Admirals do not micromanage the way Army generals do. Still, here again, we have hidden players in the form of Krulak and the MACV Staff plus, yet again -- a direct line to DC.

To see how little some things change, look at Iraq. Sanchez, wrong man for the job -- but the system said he had to stay. Abizaid, not a micromanager, tolerated that and him for 18 months. Then Casey, wrong plan -- no change. To his credit (IMO) Abizaid tried to get CentCom out of micromanaging the theater and was sort of successful, they're better than they used to be but still interfere with subordinate commanders way too much. Now, they have Petreaus to deal with and that direct line to DC is allegedly again in operation (though I'm not sure I believe that)

So personalities are a huge part of it -- and all items and people that effect events are frequently (I'd even say usually) not terribly visible. Add in a direct line to DC and the thlot pickens...

Thus, my answer to your original question:
"How could a higher HQs such as a GCC with 2 theaters of operation in its AOR better support the HQs charged with achieving policy objectives as they relate to those two wars?"
would be to leave those tow theaters alone and let them do their job while concentrating on the rest of the AO -- acknowledging that both theaters adversely impact the GGC's ability to do that. That, as they say, is why those guys get the big bucks and a Gulfstream...

I take that route because indications lead me to believe that the direct line to DC as problem is unlikely to disappear.


* As an aside, then BG Hank Schweiter, ADCS G3 for Special Ops at DA in 1966 traveled to sunny Saigon to brief on a program DA wanted to institute. He started his briefing to ComUSMACV and the Staff assembled with "General Westmoreland, gentlemen. I'll start by noting that the MACV staff is now larger than the combined staffs of Eisenhower and MacArthur at the end of world War II..." The Pachyderms did not smile -- but some of us did...

I think there's also a significant message in that vis a vis command relationships, to wit; a proper sized staff is too busy to interfere, a too large staff absolutely will interfere because you have a bunch of smart, tough guys without enough to do.