So, in a sci fi setting with fleets of hundreds of FTL spaceships...

So, in a sci fi setting with fleets of hundreds of FTL spaceships, how would you go about invading a planet of billions of people? The number of troops you'd have to carry to occupy one is... staggering, and keeping an eye on every city for signs of resistance sounds impossible.

Secure the orbitals. Who cares about the dirt?

Welcome to the nightmare that is spaceborne logistics and planetary occupation.

If you are the cravers, you eat their populace and cars and make new cravers

Food, medical supplies, manpower etc are nice things to have though.

>Leave small group of ships in orbit led by military overseer protecting merchant convoys
>Demand certain level of raw resources or build factories so the human can produce a constructed resource for you
>Leave day to day unrest an discipline to your native governors, only deal with rebels to competent for your governors to handle
>Grant benefits to consistently obedient subjugates while being ruthless to rebels
>If you need to just genocide just do so and then take immigrants from your more obedient holdings to repopulate the planet

Orbital superiority trumps everything.

Right. And if you own orbit, they have the options of trading with you, or not at all.

What happens when they suddenly can't move all of their export goods at all? economy dies, mass unemployment, goods rotting in warehouses, the whole nine yards.

Just be civilized and trade with whoever owns your orbital. It's like medieval towns surrendering after the wall is breached.

>What happens when they suddenly can't move all of their export goods at all? economy dies, mass unemployment, goods rotting in warehouses, the whole nine yards.
Eh...most planets seem to be self sufficient.

Plus if you siege a planet like you siege a castle they may never give up.

Ships aren't cheep and growing your own food in space is hard.

>So, in a sci fi setting with fleets of hundreds of FTL spaceships, how would you go about invading a planet of billions of people?

With lots of troops. A VERY rough and ready assumption that the U.S. military uses is that you need 20 soldiers per 1,000 people to really occupy a given locale. If the vicissitudes of futuristic warfare are more or less the same (but that's a huge can of worms in and of itself), you'd need about 140 million men to occupy a planet with Earth's population. That's of course, after you subdue resistance.

Then again, any spacefaring civilization likely has enormous resources, and if you have robotics, you can probably replace some or all of your occupation forces with machines. There's also the possibility of getting the locals to do some of your dirty work. But yeah, you'd probably need a fuckhuge force. You'd need a fuckhuge force just to engage on the ground anyway.

Drop a couple asteroids occasionally then and remind them who is in charge. Well, if they survive that is.

You don't.
You own the orbit, you offer materiel aid to a native political group (or groups) and support them to become dominant power(s) planetside.

Choice is simple: Be friendly and live under the rule of the orbital aliens and you get access to the unlimited resources of space, foreign trade goods and exotic/advanced stuff or don't be friendly and live in the countries that don't benefit from having a big space sugar daddy.
The rest is just so much propaganda and PR.

>Secure orbit
>Bombard the planet to kill most soldiers and destroy whatever military assets you don't want
>Achieve aerial superiority (Easy as shit now)
>Drop in millions of troops
>Obtain unconditional surrender
>Gain regular tribute under threat of further orbital bombardment
>They kill one of yours, you kill five hundred of theirs
>That is now the law
>Proceed to conquer several lower tech species in this way
>Live off the fruits of their labor.
Congratulations, you are now the local Evil Space Rome. Enjoy your courtly intrigue and rebellions.

The thing is, what are the chances a population the size of Earth are unified under a one world government?
Just bomb the not!Americans while offering local hegemony to the not!Chinese or vice-versa.
Also, if the planet is habitable by the invaders maybe set up a few colonies in less inhabited areas, kinda like Roman colonia

A company of Space Marines

>The thing is, what are the chances a population the size of Earth are unified under a one world government?


Are we talking actual earth or some sci-fi generic world with an earthlike population? The way I read the OP, I was assuming the latter, and unified planetary governments do seem the norm in a lot of sci-fi. Hence, the assumption that the planet really would need to be occupied the hard way, and that whatever puppet local troops would be created would be done so after the invasion and a period of direct military rule.

because you don't.

Simply put, even in a unified government there are tensions to be exploited, combine this with strikes on vital locations, means that you cannot control the planet fully, you can ensure the local government cooperates with you.

That doesn't work for the same reasons you can't really do that in real life anymore.

"If you don't surrender we will bow you all up"

>bow you all up
Well I cocked that up.
Guess I have to destroy the planet to cover up my cockup.

Seems reasonable.

Von Neumann assault drones for ground and air dominance after the fleet asserts orbital superiority. But I believe that the most important battle would happen in virtual space, some sort of hyperblitzkrieg that would take out or overtake opponents infrastructure. When you knockout the anti-orbital defenses on the ground (if any) you can blockade the planet and siege the population until they give in from fear of starvation/economic collapse. Fancy stuff like pheromone or drug bombing, propaganda and cultural assimilation to make the population more obedient comes afterwords, with retinue of commandos and drones left behind just in case some resistance emerges.

Rod of God.

Tired scifi trope. Anything other than a loose alliance is highly unlikely for a world with billions of people. Direct military conflict from an outsider would only serve to unite the locals against them. A much more elegant solution for an invader would be to ally with one or more the world nations and use them as a proxy to control the planet (which would be fairly easy if the invaders have better technology). If the locals survive the invaders, I could see a more centralized alliance forming at least until the threat of the invaders is dealt with. After that though, things would begin to fall apart.

>Step 1 ya go an' get you some Roks
>Step 2 ya get all da boyz on da Roks
>Step 3 Ya drop yer Roks on da Umie world
>Step 4 ya go get stuck in sum good fightin, or if the weak lil' Umies run off ya get sum good lootin'
>Step 5 ya wait for Da Boss ta tell ya what's next, or ya make yerself tha Boss cuz' yer da BIGGEST an MEANEST
>Step 6 Wait for Da Empra ta get riled up n' send somea' der puny Boyz ta scrap, if ya aint got a good fight by then ya just move on ta da next world!

Honestly this is how I would do it.
>Secure space around planet
>Launch ground invasion with soldiers and support from orbital bombardment
>Once the planet is secured rely on tons of fully autonomous drones to keep the peace
>Soldiers act as an emergency response force in case a full fledged rebellion breaks out.

>what are surface to orbit weapons and defenses
>what are keeping objectives
you must think that planes made any ground forces obsolete

>Anything other than a loose alliance is highly unlikely for a world with billions of people.


Unless you have significant cultural assimilation and easy communications. During the rise of nationalism, a lot of people thought it would be impossible for huge nations like France and Spain to have everyone speaking the same language and dialect and to all take orders from a single capital, yet they managed it.

>A much more elegant solution for an invader would be to ally with one or more the world nations and use them as a proxy to control the planet (which would be fairly easy if the invaders have better technology)

A much more elegant solution to directly invading and occupying an enemy nation is to supply arms and support to dissident elements within their nation, and use them as a proxy to control it. Especially in places where you have better technology. That's why no armies marched into other polities in World Wars 1 and 2. [/sarcasm] Elements of national unity were the principal reason you got the British Raj in India but only a series of trade concessions in China when the Europeans came a-colonizing. Not to mention that if you're working with non-humans, you might not even have the same framework to work with.

>surface to orbit defense and weapons
uh-huh
sure

worked pretty well for the rebels

It's simple. You take Tom cruise and clone him billions of times then give them laser guns.

Von Neumann armies in a box. I mean, pic related OP.

So do what the most of the European powers did to India

>Step one. Build Starbase orbiting planet.
>Leave natives alone unless they make contact first.
>Step 2, claim any suitable regions that are uninhabited, if non are available conquer isolated group.
>Step 3 remember I don't need the entire world just enough local farming colonies to help feed any in system bases.

Whole idea is stupid. There are more planets in the universe then the ones life is sitting on. They have FTL ships. You go to a planet with the stuff you want, and you get it without having to fuck with anyone. Repeat as needed.

If you must deal with other life forms. See if they have anything useful. If they do, give them what they want for it. If they don't, ignore them. If you want to be dicks, never let them leave their gravity well and they will never have access to the resources needed to be of consequence in the universe. The end.

You wouldn't, because as you said the number of troops required would be staggering. Instead, the wars in space are fought over the control of the orbit. Once you have achieved that the enemy cannot project force from that planet any longer, rendering it irrelevant to his war effort.

What you do then is to make a deal with a local power to supply you with resources in exchange providing orbital support letting them achieve their global domination objective. Eventually one of the local factions will ally with you, because the alternative is to be bombarded to stone age at your leisure. It's a win-win situation for both sides, and you don't need to lug around billions of soldiers and war material for them.

>Small strike team to replace the government or make them compliant
>Let the rest of the world carry on as if nothing had happened.

Alternatively.

>Kill every single living being on the planet
>Mine the rest / plant new seeds of plants, come back in a hundred years.

Habitable planets are where the living space is if you're not a class 2 civ throwing megastructures around. They're really valuable. Breathable oxygen? Liquid water? Easily available organics? Oh baby.

I prefer
>Build Starbase in adjacent Grav Well
>Jump it in ahead of the fleet as a fuckhuge battering ram that can solo entire fleets

Shocking, occupation has some basic guidelines

>billions

Its extremely unlikely any world other than the place a species came from will have a population quite that big. Especially since its not really feasible to transport huge numbers to found colonies in one go unless your setting has stupidly large ships.

A colony of a few million to a few hundred million with a single government is much easier to deal with.

It's just a matter of time. Even starting with mere thousands, a population can become billions very quickly.

Depends on the tech of the setting and how long the colonized planet's been habitable.

Freshly colonized, even if it's earth-like? Even a million is pushing it.

Earthlike planet that's been colonized for a few hundred years? If the government is actively endorsing pumping out babies and tech is advanced enough nobody dies to disease/starvation and a much longer average lifespan, a billion becomes a lot more feasable. Especially if you consider that said planet might be getting a lot of immigrants from another near capacity planet in search of a better life, like with early America.

You realize that most of the entire human race has been born just in the last hundred years? With space age technology achieving population of billions is a matter of decades.

>in a sci fi setting with fleets of hundreds of FTL spaceships

"We have FTL ships. Give us shit or we'll ram one into your planet and pick the scaps from the debris."

Yeah that's exactly what I'm saying nigger.

In most settings, FTL doesn't work within a planet's gravity well.

>Just bomb the not!Americans while offering local hegemony to the not!Chinese or vice-versa.

Just camp the main trade chokepoints from orbit and demand toll.

Depending on the style of FTL, accelerate to lightspeed or faster and crash into the planet. Do that a dozen times or so and you win.

Standard imperialist method. Pick a poor/unpopular minority group, give them wealth, power, and rights dependent on them keeping the rest of the planet in line.

Actually, surface to orbit weapons have several advantages over spacecraft in LEO.

*Cover and concealment. Lots of ground clutter to get lost in, and you can dig down for free armor. Meanwhile, spacecraft are highly visible against the celestial backdrop and have no cover but what they bring with them.

*Maneuverability. Aircraft in atmosphere and submarines at sea can jink and maneuver all day, only limited by fuel and endurance because they get free propellant from their ambient medium. Spacecraft can't, they have to haul all their propellant with them. Which means they guzzle it like there's no tomorrow.

*Orbital Velocity. You don't need to get into orbit with a surface to orbit missile, just high enough to drop shrapnel in a spacecraft's way at an inopportune moment. Which means you don't need a particularly large missile.Think a mobile missile launcher like a SCUD, or a boomer submarine.

*Power and heatsinks for lasers. (Yes, atmosphere attenuates lasers, but that goes both ways.) It's waaaay easier to make a powerplant of any time, resistant to attack, on a planet's surface than it is to make one for a spaceship. Ditto for weapons grade lasers. And the ground or ocean makes a dandy heatsink for both, which spacecraft can't use.

Yes, because that worked so wonderfully in Rwanda.

Britain plz go and stay go

Persian way, X-files way and arguably modern globlalization way: pick someone from the elite, the most favorable to your culture, the most dependant on the luxuries and resources you can provide him. Put him in charge.

Imperialism evolves to be more subtle so maybe an FTL-using species has more than enough technology to conquer an species without them even noticing.

Sounds like a good way to make a planet uninhabitable

If it fails after you're gone, there's no problem, no?

Once would be enough to obliterate most of the planet. And I don't mean "render it uninhabitable" I mean death star style get rid of the planet. Anything moving at c, or even a substantial fraction of c, is going to start fusion reactions when it collides with the atmosphere, which gets real bad, real fast.

>setting with fleets of hundreds of FTL spaceships
Release nanomachines into the air to rearrange the natives' brain cells to make them believe they've always been on your side.
Because the tech level you're describing is practically magic and I assume you don't want to destroy the planet.

Only reason it doesn't work anymore is people don't want to see it. In an insterstellar empire where communication is likely as long and distant as travel in the Roman empire, news would not be easy to come by.

People will tolerate plenty of tyranny from their govenrment as long as they don't have to see it. Abu Ghraib anyone?

>all these 'muh orbital supremacy' posts

T H U N D E R W E L L S

Although all things considered, it's a lot more fun for the reader to read and the writer to write if you put boots on the ground and push that logistics crap to the side unless if it miraculously becomes important to the story. It'd be boring to read about the politics that happens between a world's leaders and a fleet's commander rather than seeing them duke it out and hope for the best (Best example I can think of is The Phantom Menace)

Although, that being said, a total orbital occupation of a planet can be considered a story element. Say your character(s) are stuck on this world, and either A. need to lift the occupation or B. find a gap and exploit it. It's entire situation and based on the person's needs for the story.

Unless if you're doing hard sci-fi. In which case go orbital supremacy all the way across the galaxy.

>If you don't care about the planet.

Occupy the important bits, drop rocks on/glass the rest.

>If you do care about the planet.

Leave a garrison at the important parts with a larger force sitting in orbit. The garrison will police the surrounding areas and enforce the military law. In the event something comes up that they can't handle, a larger force drops in to support them. If they still can't handle it, pull your troops out and drop rocks on it until it stops being a problem.

>TLDR

Your at the top of a gravity well. Use it to your advantage.

...were a theoretical idea that was never proven. At best your lobbing an unguided kinetic mass at something hundreds of miles away, which will be able to see the blast that launched it and track the incoming projectile. If someone has the technology to go faster than light I'd bet they have the technology or ability to dodge something going a paltry handful of miles a second.

Orbital supremacy is the new air superiority user.

Zentradi style, of course: glass the motherfuckers.

Orbital Superiority isn't easy fellas. The ball of wet dirt is the greatest heat sink in the battlezone, the defenders can afford to sustain inefficient lasers for far longer than you can maintain your siege.

Of course, you can throw huge and fast projectiles at it, but if so, why are you trying to conquer it in the first place?

Lasers and atmosphere don't mix well.

Easy there Dukat

Von Neumann machines.

>Only reason it doesn't work anymore is people don't want to see it.

no...

the main reason it doesn't work anymore is that more efficient civilizations push your shit in

What sort of FTL are we talking about here? "Months instead of centuries" FTL, or space magic "a trip from the rim to the core is like flying from New York to London" FTL?

one man's villain is another man's hero, user

No one here seems to be considering the possibility that a race advanced enough to develop a fleet of FTL capable spaceships might have the resources, logistics and population to field an army of millions, perhaps even billions.

The estimate maximum population earth can support is around 10 billion. Let's be generous to these space-capable race and say they have perhaps 2-3 fully colonised worlds of this size. Ignoring the likelihood of a dozen smaller colonies probably existing, this would give this particular interstellar empire access to a population of 30 BILLION. According to studies on demographics and active military personnel, less than 1% of our population is currently in the armed services, and that's when we (NATO aligned countries in general) are not on a war footing. Ignoring potential factors of eugenics, force disparity, AI handling logistics and the martial nature of their culture which might sway the weight of such numbers one way or another, even 1% of 30 BILLION equals out to at least 300 MILLION. And that's just their standing army. You can bet in war-time that number multiplies.

As mentioned the ration of soldier to occupied civilian is 1:50. An army of 3 million, dependant on how many of those are actual ground troops, could occupy our current Earth at ration of 1:24.

But to answer OP's question more specifically, once the most resistance has crumbled, occupying the planet would for the most part fall to the native, aside from perhaps a few particularly high-value areas. In World War 2 Hitler couldn't possibly occupy the entirety of France, the required manpower was too great. The majority of the policing was done by the Vichy-French authorities. Same deal applies here, after the main population centres are secured all they would need to do is install a native government willing to co-operate. Any resistance movement that springs up would doubtless spend most of it's time fighting other people of the same race, not the aliens.

Don't try to take the whole planet in one go.

1st wave - Infiltration: special forces of scouts, spies, saboteurs, and assassins are stealth dropped on world. They chart the target world's weak points and strong points, and then positioning themselves to disrupt local defenses on the eve of the invasion.

2nd wave - Invasion: a few million troops secure strategically significant positions, including resource bases. Orbital superiority is used to monitor potential trouble spots and strategic bombardment is used to eliminate concentrations fo resistance.

3rd wave - Consolidation: reinforcements are brought in (or produced locally via robotics, clones, or converted locals). Initial beachheads are expanded into broad strategic fronts which push back local resistance and secure more territory. Over subsequent years centers of resistance are crushed and valuable territories are occupied.

The whole process takes years at a minimum, and decades when done properly.

>what are ICBMs
>what are lasers

>Orbital supremacy is the new air superiority user.

So it's even less capable of holding ground?

Getting anything into orbit is obscenely expensive though. And on top of that, you're suggesting the kessler cascade their own exo-atmosphere in order to maybe harm some ships? I mean, come on.

Planetbound defenses might be tough, but they have no mobility and they have to fight gravity.

If a guy at the bottom of a well and a guy at the top of it are playing dodgeball, I'm going to be on the guy on top.

Why even bother occupying it with troops when you could use drones?

Why even bother occupying it when you can glass everything and drop down prefab buildings and nanofabricators and build a city in a matter of weeks? Why bother conquering planets when you can turn random space rocks asteroids into perfectly livable habitats using nanofab and drone excavators? Why bother fighting a war when everyone is immortal AIs in their own personal pleasure simulation?

Oh, hai

Use a bioweapon that re-writes the DNA of every sapient being to be subordinate.

Done.

Exterminate the majority of the masses. Enslave the rest.

And the bean counters will give you ball squishingly high numbers.

>The hell is this?
You will demand
>The costs for repairing their infrastructure
They will reply.

Dude, this is science FICTION

Nah brah, this is science FACT-ion

>needing food
Biologicals get off, why would you have biologicals running your ships

>...were a theoretical idea that was never proven
A worthless argument in any setting with FTL travel.

This guy gets it.

Honestly, in a typical scifi where things have gotten soft enough for FTL, you need serious advantages to invade. Because even if lets say, you just blew apart the defending fleet, you're talking about INVADING the planet, not blowing it to smithereens.

This suggests that the invaders have a reason they can't afford excessive collateral. There's materiel on that planet they need, or they want the population as slaves, or even as fucking protein sources, fuck, something. In SOME of these cases, the invaders can get away with using self-replicating attacks like von neuman swarms (Not likely to exist in a setting that still has physical people to be invaded) or artificial plagues.

The defenders, on the other hand, almost certainly have no such compunctions disposing of their attackers. As mentioned in they have some advantages they can leverage in exchange for their awkward position at the bottom of a gravity well, and holy shit can they get vicious with them.

In a setting soft enough for FTL, there's all sorts of shit they could do. Leaving aside that just fucking firing regular, well-cooled lasers at them literally for days would ruin them (Doesn't matter if the transmission rate through atmosphere is only 5%, that's 5% more than they can defend against):

- Monopole based lifters could deorbit every ship manually. The reactor outputs on the planets surface can be several orders of magnitude greater than anything smaller than moon sized in orbit, and they're harder to spot against radiation background too.

Assuming this setting has any kind of FTL Interdiction, they can put down an interdictor on their own planet and make everyone think that the invading force has already been defeated, or starve them down from orbit, at which point they lose any advantage they might have had like say, not being vulnerable to relentless guerilla warfare with science fiction space carbombs.

Because drones are pretty much strictly inferior in every way to a regular person with the exception of cost and expendability. If you can develop a drone with the flexibility, intelligence, and problem-solving abilities of a regular person, all you have made is a being who will eventually wonder why he is working for you in the first place and doing all the shit jobs for you. That is how you get a new rebellion.

Well, obviously you'd whittle that down to a more managable number.

Humanity Fuck Yeah! Time for genocide and Orion Sex Slaves.

That's all well and good, but how do you propose to get them to the battlefield?

Even getting them out of the gravity well of their home planet seems ridiculously hard--like, "maybe in the next Kardashev" level hard.

It's handwavium to the point where you may as well say you just teleport them. There's no use trying to justify that kind of story rationally, just admit you want 40k style infantry clashes on other planets.

Because any civilization that really could move millions of canned apes across the cosmos has already, by definition, mastered space travel well enough to build their own worlds and start work on their Dyson sphere.