Past is precedent. Look at the distribution of U.S. military assets throughout the world. The bulk of them are inside the U.S., constantly training and rebuilding. You have to count the National Guard along with army, navy, marines and air force. Various forces are stationed within allied nations in either a logistical or "tripwire" function. American forces in Korea serve a tripwire function, while the massive US military presence in Okinawa is prepared to facilitate massive and rapid projection of force into theatre if someone is willing to test our commitment to protect our allies in South East Asia.
Right, but modern, planetary based military doctrine doesn't necessarily apply to interstellar military doctrine.
Having the bulk of the Federation military assets sitting at Earth would be pointless... it could take
weeks for them to get a hotspot.
I''d be more inclined to either move the green to the "base" colour instead of blue/black (on most uniforms, bar the TMP issue). Alternatively, it's the "default" colour and used in place of the "command" one, but engineers, medical and science officers still wear the usual colour.
That could work too, but I see the department colors as being tied more closely to job/role. A dedicated combat soldier would get the Green job color. This might not even be 100% limited to the Marines, just mostly widely used (Starfleet Security, for instance, may have their own dedicated troops who would get the green).
I really do like the idea of the Marines kind of having their cake and eating it too. The green is so ingrained in fanon that I want to include it, but it also feels wrong to not utilize the regular department colors as well. I really think the compromise here is that there is a fourth job color, just that most Starfleet departments don't have that job available.
Gold is regular security... police, shipboard security, guards, etc. Green is soldier.
Not the case during TOS, and only sometimes the case in later shows (Toddman and Oh wear gold as a senior member of Starfleet Security but Sisko, Leyton and Benteen don't. Likewise Crusher and LaForge still wear gold as an Admiral (?) and Commodore respectively.
It is somewhat willy nilly and all over the place. Note that in this specific thread, i'm not always speaking in a strict canon sense, rather in a "what makes more sense in a slightly altered version" sense. I can kind of excuse Sisko, Leyton and Benteen. Sisko was only temporary head of Starfleet Security... he may never have actually formally transferred out of whatever department DS9 would be considered (I feel like not Exploratory Corps... possibly Fleet Support?) He was still the commander of Deep Space Nine formally, and just took up an acting role as head of Security. Leyton is never actually referred to as being involved with security, and background info had him pegged as "Chief of Starfleet Operations", which I would read as Chief of
Fleet Operations. So not the C-in-C of Starfleet as a whole, but the Chief of what we would colloquially call "Starfleet". Red would be appropriate. Benteen is more of an... admin role, so it also tracks.
I do think that specifically the rarely-used "Commodore" rank may be the key there. Hitting "Admiral" rank takes one out of whatever department they were in and moves them automatically to "Command". "Commodore" or "Fleet Captain" is a flag-level position while remaining within the department. Given Starfleet's generally loose structure, it's probably much more of a formality.
I think the best way I can describe what i'm thinking is that Commodore and Fleet Captain are... Specialist Flag roles. An full Admiral is more of a Starfleet Command generalist. They may command over a particular department, but their specific commands may be a bit more fluid, moving as needed. A Commodore or Fleet Captain are flag level, but remain fixed to a particular department and assignment. For example, if La Forge wanted to continue to run the fleet museum, he wouldn't accept a promotion to Rear Admiral, which would see him assigned where needed, not necessarily where he wanted to be. Same with Oh... Oh specifically needed to be Starfleet Security, so Commodore was the right call. Fleet Captain would be an even more rare rank, used when there's a need for a flag officer but with the intent to remain in the same division.
I think those ranks may not always be an option. Picard couldn't be like "Oh awesome, i'll be Fleet Captain and stay in Exploratory Corps". It's much more situation-based, and may be more used as the chief of a smaller sub-department.
I apologize I didn't mean that exactly as worded. I meant Engineering as just a random example, like "Somebody is say, clearly Engineering".
I also admit this may not actually be the case, given some examples. Spitballing ideas out there. I am probably mixing up canon with my own stand in expectations... I was looking at something like Pressman and thinking "He's in Red, but he's Intelligence!"... having never actually established a specific color for Intelligence in canon, so... Red works.
I think alot, myself included, tend to oversimplify it to "Red = Command, Gold = Security/Engineering, Blue = Science" and it's like, mostly accurate but there's other things that end up in those.