But what can those land troops do once you put them on the surface? They'll be sitting ducks! One enemy starship in orbit firing on them (you can't just distract every single enemy ship all the time) is enough to devastate them.
Trouble is, we've rarely if ever seen starships ACTUALLY DO this. We know they're capable of orbital bombardment, but there must be some in-universe reason why this isn't usually a viable tactic in wartime. I would think that ground based shielding (of the type Soran was using in Generations) would more than suffice to hold off most orbital attacks in the short term, while purpose-built bunkers would suffice over longer seiges. Major cities would have even stronger shields, and either military facilities or population centers would be surrounded by DS9-style weapon emplacements.
Even if we exclude fire from orbit raining down on them, what will they be able to accomplish without orbital support? The defender can put huge powerfull shields around his cities/objects-of-value. How are you going to breach them without the firepower of a starship?
This has evidently never been a problem even in the ABSENCE of starships. Picard's trick of tunneling under Soran's forcefield might be a pretty typical tactic and he only resorted to a pre-existing gap for lack of a shovel.
OTOH, the Klingons seem to have developed some rather sneaky ways of penetrating defensive forcefields as of "Heart of Glory. If your shield penetrator has to be in physical contact with the enemy's forcefield in order to burn a hole in it, this would be one of the roles of battlefield sappers.
My point is, as I've alrady said: loss of the ground war will not ordinarily lead to you losing the space war; loss of the space war will ordinarily lead to you losing the ground war.
I believe, firmly, that it is the exact opposite of this. The reason is wars will always be fought for control of something ON THE GROUND, and this is the case even in the Trekiverse. Unless your enemy is simply trying to wipe out your species with some sort of planet-crushing WMD, an armed force entrenched on the ground will always have the advantage over an armed force orbiting above it.
The Romulans, by the way, were so certain of this that they were willing to risk a war with the Federation to land a few thousand troops on Vulcan. As with law, possession is nine tenths of victory.
Planetary ground war is subject to space war the way the battles on the Pacific islands were subject to the naval war. Which is why your ground troops will be subject to Starfleet, the way the Marines were subject to the Navy there.
Which is a really good example, because the marines wound up taking and holding Guadalcanal almost completely cut off from anything resembling consistent naval support.
OTOH, I must again repeat that planets are not islands and space is not an ocean, and Starships are not THAT much larger than their naval counterparts. There are no beachheads, no linear fronts; different groups of troops will hold ground in semi-mobile pockets that can stay clear of each other by tens of thousands of kilometers and only engage at a time and place of their choosing. A conventional space war will have a specific military objective with some specific economic basis; the dilithium mines of Corridan, for example, would some pretty hot territory to want to hold control over. You capturing those mines would mean removing enemy troops from a fortified position and digging them out of the mines themselves; even if you accomplish this, he could have an entire guerrilla force assembled in the mountains 100km north and you'd never know it until your ore freighters suddenly start disappearing. Obviously, one solution to this is to find the general location of enemy resistance camps and glass most of the continent around them, but this isn't practical in situations where conquest is desired.
But my point was that you still can at least temporarily suppress land-based firepower with ship-based firepower, despite the advantages the former has.
Of course you can, and vice versa. MY point is that orbiting force vs. ground force is a stalemate that the ground force can afford to sustain indefinitely and the orbital force cannot. Again, the nature of laying siege to a planet means that the planet always has more storage and ammunition reserves than your fleet does; they don't have to beat you, they just have to delay your victory to the point that continuing to attack no longer makes strategic sense.
OTOH, a ground assault using troop transports with the objective of quickly seizing enemy resources and real-estate makes the operation credible. Where before they merely had to survive your attacks, now they have to physically deny you access to usable resources and valuable positions on the ground. In the most extreme case, the defenders go from sitting in a bunker reading comic books while your phaser barrage pounds away at their shields, to suddenly exchanging phaser fire with a ground force a dozen meters from their doorstep.
But if you took all the movies that are about marines, I'm pretty sure that at least in one instance you would see the Army or some other part of the US military or at least hear them get mentioned. OTOH, if you take all the movies and episodes about Starfleet, that's not the case.
I guess the MACOs don't count, then?
But arranging transport through air (or in Trekverse, space) means it's not 'just land troops' anymore, right?
It's not an airforce if that's what you mean. Or at least, last time I checked paratroopers do not consider themselves to be aviators.
And someone else's territory will also be interstellar space in in the Trekverse. Which means you'll first have to ensure control of that space (or your ally will have to) and for that you'll need starships.
You're again making the false space/ocean analogy. We've seen from the Trekiverse that MOST borders between governments are quite porous and poorly--if at all--defended. Even in time of war, a perimeter designed to deny access to a region of space around a contested planet would be impossible to maintain even if you knew exactly when the enemy would be arriving and what his strength was.
A troop convoy meant to establish a garrison on a hostile planet wouldn't need an entire fleet for an escort. It would really only need... well, an
escort. A couple of Defiant class ships would probably suffice for that, even if the enemy knew exactly what was coming and was in perfect position to repel the invasion.
And when all else fails, misdirection usually works, as the Romulans were once again counting on in "Unification."
That's why I said Earth wars and militaries and interstellar Trek wars and militaries aren't fully comparable...
But see, they're DIRECTLY comparable. We have Earth and all its landmasses. We have a three dimensional space around it that is MANY orders of magnitude larger than the pacific ocean. We have X number of ships tasked with defending those landmasses from invasion from all directions.
Only in terms of NAVIGATION is any comparison with the pacific war even slightly valid. But the "islands" are entire planets with more total landmass than the allies even controlled during WW-II; the starships are not more than 3 times the size of their WW-II counterparts in all of this, and not THAT much more numerous to boot.
To quote you: "Its continuing mission, to catalog new resources, to seek out new enemies or new members for our Federation, to boldly colonize where no man has colonized before!", eh?
As an ulterior political motive, it makes sense. If the Federation is not militaristic in the line of, say, the Romulans or the Cardassians (or even the 22nd century Andorians) then "Go and find us something we can use while your at it" would make a good subtext for the exploration fleet's operations.
Food for thought: given the vastness of space and the incredible expenses involved in exploring it, different races probably adapt their space forces from whatever it is they want the most. I had, for example, theorized that the Gorn space fleet is basically composed of an armada of extremely heavily armed fishing trawlers; the fleet spends most of its time gathering up rare organisms from other planets with high nutritional value and/or exotic demand to their consumer base, and access to some of the best spots (Cestus-III, for example) are sometimes blocked by other aliens with competing interests or a general a lack of willingness to coexist. The Malon fleet was likewise organized around their garbage haulers, the Vidiian fleet was built and optimized for organ harvesting, and so on.
