I'd think you'd need some pretty big-ass shield generators to consistently stop starship-size weapons. We're talking city-sized shields here. How are your landing troops going to erect those in a contested landing?
Each of DS9's three shield generators are the size of banquet tables, and this with fifty-year-old Cardassian technology. On the Starfleet end, the shield generators used in "Lessons" were considerably smaller. At least, not so large that you couldn't transport one in the back of a shuttlecraft.
The main problem may be power requirements, drawing energy from a fusion reactor as on a starship or a space station. OTOH, we don't really know the relationship between shields and reactor power, nor is it really understood what "shields at 38%" actually means. I would assume that most shield setups are actually based around some sort of capacitor that stores a fantastic amount of energy that can only be charged gradually by a ship's fusion reactors.
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.
Might. Or it might not and the defenders are usually smarter than leaving such an obvious hole in their defenses. Not to mention that, while you shovel, death is still raining on you from the sky.
I wouldn't exactly bet the farm on a starship's ability to reliably target and attack single individuals in rough terrain very close to urban population centers. OTOH, if you're the one LANDING on the planet in the first place, the defenders probably aren't going to sit there behind a wall of shields waiting for you to get into position to circumvent it and then attack at your leisure. They're probably going to counter-attack and keep you from mounting an effective assault; if they wait until your entire force is standing a few meters from your forcefield, it's probably too late.
That was just a small scale shield designed to stop people right? Not starship-grade weapons.
It's a fifty gigawatt forcefield. Depending on how shields actually work, that's almost on par with a starship's defense shields.
And anyway, something like that might be posible - but why are you supposing it would be any easier than just doing some technobabble from orbit...
Because a military organization would have a purpose-built device specifically for the job of compromising enemy shields for boarding purposes (the Klingons have one that is effective against small security fields, for example, as do the Jem'hadar). On some level this would simple be another facet of ECM/ECCM, but a military organization would have specialists who spend most of their time practicing the art of shield/jammer/scrambler penetration.
I'm not denying you need ground troops to finish a battle/war. But you don't lose your control of interstellar space just because your ground assault failed.
Then why do you cite Okinawa and the Phillipines, in both cases of which the ground assault DIDN'T fail?
That, after all, was my point about Guadalcanal. The Japanese WERE able to land a sizeable ground force after the U.S. Navy was forced to pull put. They were unable to retake the island, and the Marines remained in control until reinforcements could return. The difficulties experienced by the Japanese would have been compounded a thousand fold if they were attempting to assault an entire PLANET, where the defending Marines would have a zillion places to hide ammo caches, spare parts, setup ambushes and launch raids on their supply lines. Add another three dozen Henderson Fields each with the local Pappy Boyington running a squadron.
And here's the clincher: though the space war dials up everything else in this equation, the only thing that DOESN'T change is the size of the invading force. Even if the Romulan fleet is ten times as large as the military of the entire human race, the Romulan EMPIRE spans hundreds of worlds and hundreds of light years that have to be tightly controlled at all time or risk rebellion by its various subjects; concentrating the bulk of their fleet to capture a single planet may be strategically impossible.
I'm not sure how that is different from sea/ocean borders?
Because the Ocean is a two-dimensional surface with a series of lines that an attacking force MUST cross in order to enter attack range of an enemy target. Not so with space, where that "line" becomes a vast plane rolled into a spheroid with a surface area that could cover a thousand billion pacific oceans.
Why? The Dominion managed to stop all but one Starfleet ship from reaching the wormhole. It took the Klingons to breach their lines and even then only one ship got through at first.
I still haven't figured out why they bothered to slow to impulse and engage the Dominion in the first place. Their fleet was clustered together in a tight formation a couple dozen kilometers across; it wouldn't have cost them anything to send a dozen of their fastest ships to go AROUND them at warp speed, assuming they bothered to slow to sublight at all, and again...
why did they slow down in the first place?
I admit it, this one just leaves me utterly confused.
A small escort is enough if your protecting against a small scale pirate or raider attack. But what if your convoys run into a 200 hundred ship strong fleet?
I expect the inexplicable plot contrivances will cancel each other out; the troop transport will slow to impulse for some reason, and those 200 ships will all attack one at a time.
Realistically, though: if the enemy has a fleet that big just to intercept three transports and two escorts, chances are your entire command staff is in contact with his intelligence service, which means the interception fleet is the LEAST of your problems.
It's just that you were the one "accusing" me of subscribing such ulterior motives to Starfleet a few posts back.
Actually, I'm describing an ulterior motive of the POLITICIANS. Starfleet has always been pretty clear about its interest in natural resources.