I think the closest example is Nazi Germany attacking the USSR and Imperial Japan attacking the USA. Afaik the Japanese were not as suicidal as it appears, they had a particular goal in mind and it was all going to hell anyway.

And, again afaik, the USSR was not respected as much and the Red Army was though to be a push over by both the Axis and Allies.

Now this is not an attempt to talk about WWII, obviously, just some context to why it is possible to have such a scenario.

And so my story begins with an alien fleet that appears in our solar system on a sunny, ok it's meaningless is space but let me have it, Saturday and starts approaching earth fast.

A week later an alien "invasion" is launched

So what is the aliens thinking?

First of all they are a splinter group from their "state" they are radicals and believe in their superiority over everything. And they did arrive with technology the likes of which we can only dream of.

They also estimated that since humans are already divided into rivaling nations. It's much easier to launch separate attacks on each state opposed to what would happen if we had one single unified military like they do.

The military operation had specific and clear goals. So their initial target Are:

Military bases.

Human infrastructure.

Their ultimate goal of the attacks is not total annihilation but to weaken the collective human race enough so to bring them to the negotiation table so that a favorable agreement can be reached.

This agreement they want is just them getting lands to settle with absolute power over them and special statues among humans. Like they can't be trialed at our courts and so on. Which have a lot of historical bases.

I could not make them blind enough to believe they can destroy the human race.

Now they really want to destroy the military bases but when it comes to infrastructure they see the need for that later on, as they don't want to mess things up too much, so they won't focus on that heavily and won't utterly destroy them. Just enough attacks to cripple the country for a while.

Can't they just come in peace? No.

Why bother with earth in the first place? We are the only habitable planet they encountered, and having access to our own tech and infrastructure would actually give them a lot to work with. Because again they are not an arm of their state, they did not bring all the coolest toys with them from their own state. And so having a whole planet with more than 7 billion potential workers seems better than trying to settle in Mars.

They also see the subjugation of the humans as an important point in in validating their own believes and ideology.

What type of technology is available to them?

So far the most logical thing is a highly advanced ships with nearly unlimited power and large manufacturing capabilities. They have lot of drones and a crap ton of plasma and laser based weapons and vehicles. Most of which are controlled from their own ships by pilots or assisted computers, they don't have or like AIs.

The rest is up to you.

Their numbers can't be more than a few millions but that includes civilians so their actual military can't exceed half a million that if they put all capable males into it.

So when it comes to ground troops they don't have much. They use drones and their own tanks. Those tanks are obviously much stronger than ours but they can be taken out.

They don't actually have much of an air force, nor do they posses vastly powerful startship cannons. The air force can still be better than ours and still be decent. Their own ships are mostly armored and protected by shields for ship to ship attacks. But not top of the line invasion ships. This ties in with the fact they are a splinter group not the actual military arm of their race. So you if you want to add using their own ships for the attack do so but without making planet killer type of weapons.

Can they call support? Heck no.

Why focus on them? Because it's much easier to change the aliens than to introduce plasma tanks to humans with all the complexity that brings.

Do they have access to biological or chemical weapons or nukes? Initially they don't have them.

What is their military creed like? Mostly using overwhelming tech in the form of tanks and drones and so on to win the war.

So the focus is mostly on the type of vehicles they have and how to use them. But this would depend on the answer and I'm open to suggestions.

What is their biology like? Human like. Only more fragile and they detest manual labor and actually fighting.

Since they are space faring with vastly superior tech. I think they can turn the entire earth to glass if we wanted to, and thus the question and premise don't work! First they don't want to do that, second they actually have limitations. Also it's not fun.

Hopefully that's enough information.

This is getting long and so to sum it up they need to have a more advanced army, and initially do a lot of damage to our states but have their own "brilliant" plan fail within a time frame that I'm flexible to because it would depend on what you guy suggest.

And so I just want to focus on the answer to the main question and other points will have their own questions.

So. What is their overall military capability have to be in order to attack us but actually fail in achieving their goals?

Edit 1: to clarify the original idea is that they did not plan on our own invasion per se. They just escaped their own state and "happened" to find our little slice of heaven. So it would seem weird that they arrive with specific weapons or ideas to fight us.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – L.Dutch - Reinstate Monica Jun 27 '20 at 13:31
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    $\begingroup$ How is this different from Harry Turtledove's Worldwar series? $\endgroup$ – Eric Towers Jun 27 '20 at 22:30
  • $\begingroup$ @EricTowers There are many differences (splinter group vs. imperial army, different development rate from humans, experience with conquest, different time in human history). The basic military problem is the same, and I've recommended reading Worldwar in the chat room. $\endgroup$ – Patricia Shanahan Jun 28 '20 at 2:14
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    $\begingroup$ tl;dr? - please make your post easier to read. $\endgroup$ – Martin Schröder Jun 28 '20 at 11:07
  • $\begingroup$ @Martin Schröder. Sorry. What is wrong with it exactly? $\endgroup$ – Seallussus Jun 28 '20 at 19:12

22 Answers 22


Technology Required to Invade



  • Sufficiently high enough specific impulse to accelerate to a significant percentage of the speed of light (0.1c, 0.2c)
  • Sufficiently high thrust that you could push accelerate a large load (thousands of tons) to cruise speed in a reasonable amount of time (around a year or two)


  • Anti-matter. At 0.3% mass-energy efficiency, as impressive as fusion power sounds, just doesn't cut it. You'll need $mass \times cruising speed^2$ energy to accelerate the fleet to cruise, and almost as much to slow back down. With anti-matter, a 20% speed-of-light cruise will require 8% of the fleet weight to be fuel (if the anti-matter power is 100% efficient); 16% fuel weight for a 50% efficient anti-matter plant.

Mechanical Engineering

  • There are plenty of stars to launch an attack from within 10 light years of the sun. If cruising at 20% the speed of light, a 10 light-year trip will take 50 years (about; not including acceleration and deceleration) to arrive. The aliens need to build equipment robust enough to reliably start after half a century off.


  • Hibernation : the invaders will need to be able to put troops into an aestivation or hibernation that can be ended on arrival


  • Autonomous Systems : the fleet will need to have semi-autonomous or autonomous systems with close to a human level of general intelligence to deal with all of the surprises a long space voyage could bring.

What Might Go Wrong

If the fleet takes a 10 light-year trip at 20% the speed of light, it will take about 50 years to arrive in the battle space. Additionally, light has a finite travel time (ten light years in this case). If an alien fleet arrives in 2020, invasion planners were looking at data from the 1960s when purchasing equipment and selecting targets.

In the 1960s, the Earth's population was 3 billion. Humanity had just gone through 2 back-to-back world wars (the 1920s and again in the 1950s) and we appeared on course for a third. Invasion planners might have assumed no (or very little) growth in the number of defenders and stagnant growth in technology (which still did not even include orbital space flight).

Based on the Alien Tech, and the Intelligence They Had Available, Here's an Order of Battle

(7) Missile Destroyers (40x 12 terajoule anti-matter missiles) : for use against military bases; one for each major belligerent during WW1 and WW2

(1) Aircraft Carrier (90x orbit-to-atmospheric small fighter craft) : only need one

(300) Troop Ships (10 thousand ground troops ea.) : - assuming 1,000-to-1 effectiveness of ground troops and 3 billion person population of Earth

Playing Through It

The fleet arrives in 2020. Where planners expected to arrive in orbit undetected, instead many observatories and satellites detected and tracked the fleet's approach.

Where planners had brought no orbit-to-orbit defenders (the fighter craft can fill the role, but were fitted for orbit-to-air and air-to-ground), there are now [26 countries with orbital launch capabilities]. Five of these nations have demonstrated nuclear weapons capability, and another four claim to have capabilities. 4

Rather than the uncontested landing of ground troops planners expected, the fleet encounters a primitive, but passable orbital defense. The alien ship engines are high-tech marvels for their efficiency, but under- or equally- perform chemical rockets.

And, completely unexpectedly due to the cold war, several nations have undisclosed, but supposedly enormous reserves of ground-to-orbit nuclear weapons.

Alien planning software has been active during the trip. It has observed with horror as peace has spread out over the Earth, and most of the plan assumptions are now invalid.

Nevertheless, the fleet commander attempts a contested orbital landing. The missile boats, carrier, and many troop carriers are destroyed during the battle.

The troops that do land find that the military bases that were valuable 60 years ago are now mostly closed. Tactical anti-matter warheads launching at pre-loaded targets detonate around abandoned facilities in the wilderness and desert.

The alien ground troops have to encounter larger ground and air forces than they expected, higher tech defenders, and most of their orbital support lost or wasted on worthless targets.

  • $\begingroup$ The speeds are 'doable' in theory. NASA etc are currently modelling various forms of propulsion that could reach those velocities. Anti-matter is also doable as a power source. Again its being looked at by humans. The reactionless drive however involves some form of 'unobtainium' i.e you'll need techno babble to explain it's existence. Interestingly if you use antimatter powered rocket propulsion you create a scenario at some point in the flight where the aliens have to 'flip' their ships and start decelerating. And at that point they are going to advertise their presence. $\endgroup$ – Mon Jun 28 '20 at 1:38
  • $\begingroup$ So depending on how efficient your drive is/what Gs the fleet can pull you can set an arbitrary point in the journey where human astronomers detect the appropriating threat. This gives Earth X amount of time to prepare depending on how you plot the story rather than just turning up unannounced and the shooting starts. $\endgroup$ – Mon Jun 28 '20 at 1:41
  • $\begingroup$ This is pretty good. I might consider changing things enough to fit such a reasonable plan. I mean they are not geniuses and I can even make the scale worse. Maybe even 1890? Heck. They bought the old info for a lot of money and thought: this is where we will set our Utopia and humans are so stupid. But their backwater planet is just that so the guy selling the info did not get the 2020 update, or rather steal it, so they are grossly outmatched when it comes to actually doing the invading. You know what they say "Generals are always prepared to fight the last war" $\endgroup$ – Seallussus Jun 28 '20 at 5:04
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    $\begingroup$ And I know you don't like it but don't discount using (small) asteroids as you our heavy artillery. The really big plus with this is that you don't have to bring your ammunition with you. Its literally free for the taking upon arrival. And since you control the 'high ground' you own the resource. I know I harp on about it but any aliens with hostile intent would be mad not to utilize what amounts to a free gift. And your scenario is ideal in the sense that they can't drop a dino killer on us because they need the real estate intact. $\endgroup$ – Mon Jun 28 '20 at 7:53
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    $\begingroup$ They are not being tested per se. The theory behind them is being investigated. Bench tests are being conducted to determine if any 'warp like' effects can be observed. The 'jury' is still out because nothing concrete has been produced to date. In fact most theoretical physicists dismiss these attempts as a waste of time. I'm not saying they are right mind you, just that no definitive results have been produced. That being the case I based my comment on what we 'know' would in theory now. Not what might be possible 10, 50 or 100 years from now when 'new' physics are finally proved. $\endgroup$ – Mon Jun 28 '20 at 12:20

Most science fiction trivializes much of the space travel, but it would add lot of useful limitations if they did.

Space travel is tough. It should take a long time to get anywhere and even if you do have FTL there could be limitations that make carrying virtually unlimited weight in a ship impossible. So if you attack someone you bring three things: the people that you are going to invade with, a small amount of basic equipment to start the invasion and the manufacturingplants required to keep the war going after the initial engagements.

So the basic method of attack would be to enter the system. Land troops at some important points to secure resources and places to land your production facilities (or launch materials into orbit to the production facilities there). Then start a brutal war of attrition across the planet's surface in order to gain more and more control, hoping your production capacity and technology are adequate to win. "Real" militaries attacking similar tech civilizations would have access to space-based mining, refining and production facilities that remain in-system to produce everything needed while the defenders try to track them down and fight them before they have produced sufficient materials, but your splinter faction does not have access to those.

Your faction ends up not having enough people, resources and/or production facilities to win, either through miscalculation or successful attacks by Earth's indigenous forces.

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    $\begingroup$ why would you land troops and not mine asteroids, which A don't fight back, B are drastically easier to get resources from,and C the left overs can be used as cheap high power munitions. $\endgroup$ – John Jun 27 '20 at 13:54
  • $\begingroup$ @John because they didnt have access to that, as I mentioned? And the distances and limitations of space travel might mean that things like food and energy are running low without resupplies from elsewhere. So you want to land fast and get your resource gathering and production active ASAP. Which could just be food and water production first and military production second. $\endgroup$ – Demigan Jun 27 '20 at 15:03
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    $\begingroup$ If they can get here from another star, they have solved the closed cycle bio-resource problem, it is a prerequisite, and they can get raw material like water and minerals much easier in space. $\endgroup$ – John Jun 27 '20 at 15:12
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    $\begingroup$ @John if they have FTL available, which is likely since its still the same splinter group, they could be relying on cheaper lifesupport systems as they dont need more to get where they need to be. Or they could be limited in their fuel&energy capacity so they require time on a planet or risk running out during refinement and refueling. The point of my answer: something limits them. It doesnt matter if its lifesupport degrading due to FTL, the splinter group not havig enough time to prepare or that they simply have claustrofobia and need to land before losing it. As long as they are limited. $\endgroup$ – Demigan Jun 27 '20 at 16:42
  • $\begingroup$ @Demigan why would Earth food even be compatable with the aliens? Why would energy be easier to gather on Earth? Just collecting fissile from an astroid is easier than on Earth, Helium-3 could be collected from one of the gas giants... Its really bonkers to go down a gravity well for "stuff". $\endgroup$ – Aron Jun 27 '20 at 19:14

Divide and conquer.

/First of all they are a splinter group from their "state" they are radicals and believe in their superiority over everything/

That is their leaders. Under those leaders are competent military persons. Within the first week of conflict it becomes clear from military decisions made who the competent military persons are. This is not a hive mind or a monolithic intelligence.

One of the reasonable military leaders is approached to parley. This competent military person has thrown his lot in with his radical leaders to escape his homeworld but his actions on the field have shown him to be less radical and more pragmatic. He sees how it is with the humans and realizes they have bit off more than they can chew. A land for peace proposition is made, with the condition that he be the new alien leader. He is no less arrogant than his leaders and sees personal and societal gain in the deal.

This reasonable leader turns and leads a military coup, with assistance from humans. Many aliens respect this leader and the coup does not take long. The radicals are overthrown and imprisoned. The humans keep their bargain and settle the aliens on earth under circumstances much more favorable to the humans. The humans also get all the alien tech.

  • $\begingroup$ Oddly enough I planned something similar. However my question was trying to break the process piece by piece. So just focusing on the actual overall military of them. $\endgroup$ – Seallussus Jun 26 '20 at 22:45

They had fraction of C drives rather than FTL drives.

So when they surveiled Earth from their home a few hundred or so light years away, they saw a backwater bunch of apes barely capable of fighting off the most basic of plagues. Decades went by and technological advancement was minimal at best. Even being generous in estimating human development, the aliens figured we might be hitting the industrial revolution with a population of a few hundred million by the time the attack fleet/generation ships arrived.


You don't need much to beat a bunch of states armed with muskets and maybe discovering a telegraph. That force might not be sufficiently equipped to deal with an order of magnitude more enemies, equipped with space-capable rockets, nuclear arms, and a high speed worldwide redundant communication system.


They Let Themselves Lose.

The only truly logical explanation is that the aliens secretly let themselves lose.

Any other extraterrestrial civilisation capable of interstellar spaceflight is likely to be millions of years, perhaps even billions of years, more advanced than us. To give you some perspective, it's the same as us going to war with some fish in someones backyard pond. Or actually, more like going to war with an amoeba in that pond.

So if you need them to lose, then it has to be their choice to lose. By why would they want to lose? I can think of many reasons:

  • Because although our planet is nice, in reality, they have no real reason to win. Winning is not the real goal for the aliens.
  • The war is a test. Not of us, but of themselves, to see if they could win with limited means. Kind of like us placing chemicals in the backyard pond to see if it will kill the amoeba, but we don't really mind if it doesn't work.
  • They are curious how we would survive, to assess perhaps, or alter, our future trajectory of civilisation. Kind of like we are selectively breeding animals to make them more suitable for our use, entertainment or simple curiosity.
  • A completely alien reason we cannot comprehend. I mean like 'because our scripture says so' or 'because it looks nice' or a reason we may indeed, never know.

To answer your question: So your technology level could be any level, and theirs too. To an alien, it matters not if you have guns or not, electronics or muscles. These are developments that have happened in a couple of hundred or thousand years: to them this period of development is a 'blink of an eye' in a billion-year timeframe such that it would almost seem instantaneous. Their 'military' technology level will always be beyond ours, far beyond anything we can comprehend now.

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    $\begingroup$ @Seallussus the trick is if they can get here from another star they have to technology to make any of their technology in basically limitless supply from asteroids. it is like saying thirty soldiers which the manufacturing capability to make billions of robots and drop a dozen nukes could take over a continent, which they could. If they can get here then they don't need anything we have, and the can wipe us out with a few rocks. $\endgroup$ – John Jun 27 '20 at 4:35
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    $\begingroup$ I don't think this deserved a downvote, it is an extension on @Seallussus original narrative that gives a stronger precidence towards 'testing the water' or indeed playing the long game to understand how they can achieve their ultimate goal. I like this answer. $\endgroup$ – David Barker Jun 27 '20 at 10:43
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    $\begingroup$ @John, This is just trying to force a premise change to fit what is the most "reasonable" solution to a non existing problem. We can create nukes. Yes. Can you yourself make a nuke? Automatic rifles are simple. Can you make one even with access to the materials? So it boils down to a bunch of people on a couple of ships with access to certain things without full access to all what their state offers. These limitations are in the post, to give context , and are not a part of the discussion because creating the perfect invasion is a joke. They drop asteroids, engineer a disease...etc. $\endgroup$ – Seallussus Jun 27 '20 at 17:24
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    $\begingroup$ @Seallussus dropping and asteroid is not like building a nuke, it is very simple, it just requires a lot of energy. a ship capable of interstellar travel is all you need, and they have many.And it is not "a couple of people" the OP specifically states they have millions of personnel. $\endgroup$ – John Jun 28 '20 at 0:17
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    $\begingroup$ @chiggsy is just the high end you can drop any size rock you want, you can literally dial in the level of destruction you want. Asymmetric warfare only works when the lesser power has decent access to attack the stronger, earth will have zero access to an alien power. They never even have to land. $\endgroup$ – John Jun 28 '20 at 2:46

Sir, we have run out of bombs.

The plan is to simulteneously launch a bunch of tactical nukes or plazma/laser beans at all government buildings and military sites. This will leave most of the infrastructure intact while taking out the majority of world leaders and anyone who could pose an organised resistence. Then they move in an mop up.

Since this was the plan and space travel is expensive they only brought enough weapons for the first devastating attack. Then they were all out.

It usually works. After that show of force the planet capitulates. But humans are special because we were

(a) Too stupid to stop fighting. Sure the aliens can land their 25 hover tanks and mow down a bunch of civilians. They act all scared for a while and start doing what they're told. But the moment you move on they start acting up again.

(b) Too stupid to reorganise ourselves so the aliens actually had someone to negotiate with. Since there was no one in charge to negotiate with, the rest of the plan was a bust.

  • $\begingroup$ "Too stupid to stop fighting" sounds a bit like the situation at the start of "The Course of Empire". That book is absolutely brilliant, not least because the setup is "twenty years ago, aliens invaded and humans lost". (Go read it; the electronic version is free.) $\endgroup$ – Matthew Jun 27 '20 at 0:04
  • $\begingroup$ they literally can't run out of bombs, because rocks work as well as bombs if you are in space. $\endgroup$ – John Jun 27 '20 at 13:50
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    $\begingroup$ @John I propose that $-$ in addition too only bringing 25 bombs $-$ the alien fleet didn't bring the gear needed to weaponise asteriods. $\endgroup$ – Daron Jun 27 '20 at 14:15
  • $\begingroup$ That is not actually possible, they have an engine capable of interstellar travel, they can literally use the ship they came in. Also whatever delivery system they have for the bombs can be used to push a much more destructive rock, then you have the bombs themselves. weaponizing an asteroid is just math and propulsion. $\endgroup$ – John Jun 27 '20 at 15:15
  • $\begingroup$ @John Yes they could literally drop the ship they came in. But that's a bad ideas since they only brought one ship with them, and being in orbit is much safer than being on the surface. $\endgroup$ – Daron Jun 27 '20 at 16:16

It is just about impossible for alien invaders to lose.

Interstellar travel requires control of vast amounts of energy. A spaceship capable of sufficient velocity change, or Delta V, to acclerate its mass to interstellar travel speed, should have sufficient Delta V to change the orbits of many asteroids and comets to fall toward Earth, and then to put those asteroids and comets in orbit around the Earth. When Earth has tens, hundreds, or thousands of asteroids in orbit, and the aliens can de orbit any one to hit any target on Earth, they can demand the total surrender of any group on Earth.

So it is just about impossible for aliens to fail to conquer Earth.

That is why all realistic stories about alien invasion end with alien victory.

So you will have to do a lot of thinking to come up with an poor alien conquest strategy that doesn't use their technological advantages well, leading to their failure to conquer, and then do a lot of thinking to come up with a psychological reason why the aliens choose such a poor conquest strategy.

  • $\begingroup$ I mean no offense. My battery is dead, can you give my car a push? Dude. That's an old car with a dead battery! get a new one. Alright. I just need to get to work. Can you help me out? But it's old. And you should not drop any money into fixing it because it wont be worth it. Just get a new one. It's more reasonable that way. Fine. I'll ask the next person. Good day. No man. Seriously. Don't even bother with anyone else. It's not me, it's the stupid car, just get a new. This is basically a summary of this comment. $\endgroup$ – Seallussus Jun 27 '20 at 17:43
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    $\begingroup$ @Seallussus It's an answer, and frame challenge answers are explicitly allowed on this site. Be nice. $\endgroup$ – wizzwizz4 Jun 27 '20 at 22:20
  • $\begingroup$ @wizzwizz4, Unlikely. Like ever. I can literary create a much weaker invasion that would result in a much worse scenario. He is confusing the popular movies with this particular scenario. I also have a lot more on how they did this and that and why this and that is not done. Anyway if he is challenging anything it should be their abilities, which I said I'm leaving to you guys as to fit the outcome. For example limit their FTL travel, which I already have, or their personal or anything. But don't go around claiming no alien invasion can fail. $\endgroup$ – Seallussus Jun 28 '20 at 4:31
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    $\begingroup$ Unless the invading aliens are stupid, or don't want to invade, their invasion will succeed. $\endgroup$ – wizzwizz4 Jun 28 '20 at 9:17

It isn't their ship.

As several other posters have correctly pointed out, any civilization capable of building a fleet capable of reaching Sol must be so far ahead of us that we wouldn't even be children to them militarily. Taking out our satellites from orbit would cripple civilian communications and the economy, and pin point kinetic strikes would take out communications nexuses and military logistics points. If they can jam radio frequencies or decrypt our comms, the military's back to hard lines and PTP connections, both of which are short ranged (and PTP is line-of-sight), severely limiting our ability to call for help and coordinate troop and supply movements. We aren't capable of contesting their orbital superiority, either, so we literally cannot make any strategic progress. If they built they ship they arrived in, they can't lose.

So your invaders not only didn't build the ship, they barely understand how it works. Maybe it's an remnant of an ancient precursor civilization, maybe their species is a client of some much more advanced overlord, and this splinter somehow managed to seize an old, run down ship. It certainly could be a warship they just don't understand, or it could be a civilian craft; the tech is so advanced they can't tell the difference. So the ship could possess cannons that could destroy the planet or swat our satelites, aircraft, ships and bases, but the computers are locked down and the aliens haven't a hope of cracking them. Maybe the ship was built to be a local transport, and the FTL drive was a jury rigged piece of junk that broke beyond repair when the ship arrived in our system. Most of what they do use isn't used for it's intended purpose, with a corresponding loss of efficiency and increased component wear (which they can barely cope with). The ship has any number of ways to get all the power it needs just by sitting in orbit, but those systems are broken, locked down, or unknown to the invaders. Heck, maybe the main engines don't even work anymore, and they're putzing around with station-keeping drives that would take literally weeks to accelerate to respectable intrasteller (not a typo) speeds, and weeks more to slow down again. Not to mention, the aliens can't use the ship's tractors to nab a handy asteroid even if they had the thrust to tow it.

This puts your aliens in orbit around Earth and gives them advanced planetary-scale technology, but removes the reader's objections that any species capable of getting here is incapable of losing a war against humanity they don't intend to lose. They have to use what they have, and can't go back for more. Nor can they produce more, because even if the ship has that capacity, it's broken or locked down or other systems it relies on to gather raw material and/or power are broken or locked down.

  • $\begingroup$ I considered pointing out that while infantry portable laser and plasma weapons might not be quite as technologically impressive as FTL, they'd still place any civilization in a "can't possibly lose to Earth" level of technology. I didn't, because considerably fewer people seem to have thought through what it would take to get an ionized gas projector into something as rugged, reliable and compact as an infantry weapon than have done so for FTL ships. $\endgroup$ – Dallium Jun 27 '20 at 20:46
  • $\begingroup$ gotta upvote the "alien nation" solution $\endgroup$ – John Jun 28 '20 at 0:37
  • $\begingroup$ Driving a car is quite different to actually being able to build one. Even if you have some technicians able to repair it (based on spare parts), I wouldn't expect them to grok the equations on which the motor works. Also, I would find unlikely they would be able to decrypt our communications. It would be hard even if they were in the clear. They might have the technology to break encryption algorithm, but they would need to understand our language (English, French, Navajo...?) to begin with. Plus all the military jargon used on top of it. $\endgroup$ – Ángel Jun 28 '20 at 0:51
  • $\begingroup$ Satellites seem like a target for the aliens. However, I don't think we rely so much on them. Most communications go through cable lines, even intercontinental ones. Earth soldiers could end up with a non-working international satellite phone, but being able to connect by using their civilian smartphone connected to a nearby 5G tower. $\endgroup$ – Ángel Jun 28 '20 at 0:55
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    $\begingroup$ Niven-Pournelle's Footfall has an intelligent race fail to conquer earth, narrowly. Well worth reading. $\endgroup$ – Russell McMahon Jun 28 '20 at 9:31

IDOLIZE HUMANITY: You need a psychology that is sufficiently human to make their motives relatable, but sufficiently alien to defy conventional logic. Given the overwhelming practical advantages such a race would have over humans, there needs to be some flaw in the alien approach that leaves them vulnerable. Overconfidence and arrogance have been done a MILLION times, and is frankly easy and boring. They believe in their own superiority, yet detest fighting. They have a need to conquer humanity to satisfy their own self-worth and philosophy. They don't want to conquer the entire planet, but instead want to set themselves up in a place of privilege alongside the human race. Why do they want this? Because the think the Nazis were prophets, and idolize the human race.

  • Their own culture long ago abandoned violence, but there are always those who look back on ancient practices with nostalgia. They found humans initially during WW2, and the information their probes sent back excited these folks about the "noble savages" on Earth.
  • Traditions of cultural sensitivity shape their thinking, so conquering humans is merely being respectful of how humans interact.
  • Given their admiration of humans, they will constantly overestimate what people will be able to do. Every defeat leads to panic and admiration.
  • The goal is to make the humans admire and respect them in return. While collectively they are cowardly, individuals may perform great acts of courage; not to win battles, but respect of their enemies.
  • Their emulation of the Nazis lends their behavior towards support of dictators and the establishment of authoritarian puppet governments. Right-wing revolutions would be supported, and liberal/leftist practices would bring attack and scorn. They might admire the Cuban authoritarianism, but then attack them because of their leftist ideology.
  • In their desire for human attention and admiration, they will negotiate with world governments to try and extract respect and fear. If Egypt has a strongman who encourages them to invade Israel, they would respect the dictator and invade Israel. Getting the USA angry at themselves just proves they are worthy. A proper balancing act would be for them to flirty with a global war but always back down if they think they'll start too big a conflict.
  • Play politics. So you conquered China with your fleet of drone tanks, now promise peace with Russia and trade with them. Don't invade North Korea - exterminate those Commie bastards. No use attacking Japan - you admire their militaristic history and don't want a full-scale war with the US.
  • $\begingroup$ This is certainly interesting. $\endgroup$ – Seallussus Jun 26 '20 at 22:51
  • $\begingroup$ I think it's worth mentioning that, for all their rhetoric about being right-wingers, the Nazis were firmly entrenched in the extreme left. $\endgroup$ – The Daleks Jun 26 '20 at 23:20
  • $\begingroup$ @The-daleks In this case, the reality is less important than the imagination of the aliens. $\endgroup$ – DWKraus Jun 26 '20 at 23:48
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    $\begingroup$ @ Daron That's why you CONQUER China, but N. Korea takes it too far, and you just wipe them out from orbit (to make a statement, also, and because the whole country is a giant minefield) $\endgroup$ – DWKraus Jun 27 '20 at 13:51
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    $\begingroup$ Good point. "A Titan Arum by any other name would smell just as feculent." $\endgroup$ – The Daleks Jun 27 '20 at 16:33

So far the most logical thing is a highly advanced ships with nearly unlimited power and large manufacturing capabilities.

I dissagree. The reason why they are attacking Earth and wanting it's infrastructure intact is because they lack the manufacturing capabilities.

As you say,

First of all they are a splinter group from their "state" they are radicals and believe in their superiority over everything.

This could be explained by the splinter group stealing the warships. But those are warships, and they lack manufacturing capabilities. And they didn't have chance to take actual manufacturing ships, in which case they could just grab an asteroid an mine that. Also, due to the splinter group not being official, they might lack skilled officiers, commanders and soldiers.

So we have a situation:


  • Populous
  • Comparatively primitive weapons
  • Fractured governments
  • Manufacturing capability
  • Want to defend themselves at all cost
  • Despite fractured governments, many governments and militaries know and train to communicate and fight together

Alien invaders

  • Few soldiers
  • Lack of skilled officers and commanders
  • Advanced weapons
  • High ground
  • No way to fix or create new weapons, including amunitions
  • Don't want to destroy infrastructure

The first strike might go like Japan's attack on Pearl Harbor. The aliens will hope, that first attack will destroy enough military and break people's will to resist. But due to mistakes on commander's part and fast response of the governments, this attack is met with much heavier resistance. The war then turns into an attrition war.

Next assumption the aliens might have that the governments will not work together. Again, they are proven wrong when the governments of USA, China, Russia and EU all coordinate together at counterattack. This coutnerattack causes huge losses on both sides, but makes fast resolution of the war impossible.

Another assumption might be use of nukes. The aliens might assume the governments won't be willing to use nuclear weapons on their own lands. But once the humans realize the alien's technological supperiorty and the fact they desire the infastructure, they start using tactical nuclear strikes both to destroy the alien's weapons and to deny them the infrastructure they so much need.

In this scenario, technolgy doesn't much matter. Even if aliens can destroy 100 tanks, 1000 soldiers and dozens of jets for 1 of their drones, as long as Earth's infrastructure is intact, and the Earth governments are willing to enact Total War and Scorched Earth policies, they will loose the war of attrition.

  • $\begingroup$ You are right. I need to tune down some of their stuff. Though the ships should remain operational now matter what. Probably they can't manufacture more than just their food and maybe maintain some of their equipment and repair it some but nothing to the point of being able to replace them with sufficient speed to win a war. Thanks. This answer is euphoric. Ahm. I'll show myself out. $\endgroup$ – Seallussus Jun 28 '20 at 19:18

Aliens secretly observed humans civilisation, than decided to choose different target. So conflict not started at all. And humans was too occupied on their own problems to find it

Aliens wanted to colonize Earth, because there is big oceans with clean water having good salinity level. Perfect for aliens to live in. Last time they send unmanned probes, humans civilization was just starting to build first railroads of 19th century. And aliens send few expeditions forces that will took ~ 200 years to get to Earth.

Alien expedition force used sophisticated cloaking devices and orbited Earth. Unfortunately, it was 2020 year. Aliens observed covid-19 quarantine in China, Great Toilet Paper shortage in USA, they tried to understand negative oil price panic (and their main artificial brain overheated), covid-19 quarantine in Europe and USA, Black Lives Matter protests in USA. Than they read human's wikipedia about first nuclear weapon usage to burn Hiroshima, while other civilizations they conquered used nuclear technology only for generating electricity or destroying asteroids threatening to wipe all planet's life. Also they watched some MBA broadcasts and live footage of military conflicts. Than they send few drones to find abnormal level of plastic in sea water of Earth, making it unusable for colonization.

Probably, if aliens was crazy enough as humans, they would try to deploy various biomechanic war machines like "Cthulhu" class heavy destroyers, "Godzilla" class medium destroyers, "Kaiju" class light destroyers, "Piranha" class anti personal systems and so on.

They even deployed few "Kaijy" scouts, but they died because one entered oil spill in Mexica gulf to suffocate to death, other one consumed too much plastic at Nemo point, and few ones were captured and butchered by Chinese fishermans... Aliens underestimated humans. And they asked themselves one question:


Why waste resources on capturing contaminated water and than trying to deal with natural born killers (who destroyed megafauna with sticks and stones in prehistoric time), that will probably survive on surface of planet after few orbital strikes and will start guerilla warfare or even send nuclear weapons powerfull enough to eliminate all live on their planet.

Also aliens found, that humans are predators, they like to eat burned meat of animals they killed and consume it, drinking methanol poisoned liquids.

It is something plankton eating aliens cannot understand...

Aliens did the math and decided human civilization is too crazy to mess with. They decided to leave humans killing their own keen and planet alongside.

Aliens moved to colonise Europe, one of Jupiter's satellites. At least it have clean water with funny leviathan grade fauna that can be domesticated, and humans civilization is too occupied with various strange things, so its unlikely they try to colonise Europe in foreseen future.

  • $\begingroup$ I won't deny it's amusing. But this answer must be in response to another question. $\endgroup$ – Seallussus Jun 27 '20 at 3:51
  • $\begingroup$ If I were the aliens you described, I think I'd drop a giant asteroid on Earth purely for the use of getting rid of us. Make sure you got the survivors, then come back in a few thousand years. Play the long game, get rid of potential competition. $\endgroup$ – DWKraus Jun 27 '20 at 22:54

If I understand the question your asking correctly your concept involves a failed invasion i.e. aliens arrive and attempt an invasion but for whatever don't succeed fail. Humanity (or both sides) then have to set about dealing withe aftermath of that failure social, political and environmental etc.

If this is correct then the best possible scenario is one of numbers and logistics. Just getting here proves they have vastly superior technology but that in and of itself might not be enough. You also have to assume that for whatever reason the aliens want to preserve the environment as much a possible. Otherwise 6 aliens and a large asteroid would win the 'war' with one shot.

Consider a scenario where there was a say for example a steam age civilization on Mars. Could we currently send small teams of explorers there? Yes. Could we send a fully equipped expeditionary force to conquer the planet? No. You'd be talking about launching literally tens of thousands of tonnes of soldiers, equipment and supplies into space and then following up with tens of thousands of more tonnes for as long as it took for us to establish a large bridgehead and become more self sustaining. Even then you'd still have to send thousands of tonnes of stuff they couldn't source locally for decades. Even if we had the will we simply don't have the technology to sustain that kind of logistics chain.

The aliens have the same problem only they are hundreds or thousands of light years from home! No help is coming. So the most likely scenario is that they had to fight the war only with what they brought with them. And if they didn't win with that it means they weren't expecting to have a fight a war in the first place. So a refugee vessel escaping a war or a colony expedition stumbling across Earth is the most likely option.

Yes they have access to the solar system so presumably they could build/replace at least some weapons and equipment but what they cant do is replace their 'people' because they no more are coming for at least a couple of generations,if ever. This is especially true if you assume only a limited number of the aliens on board the ship were trained as soldiers to begin with or else could be spared to be used as such. So they end up having to learn the art of fighting humans as they go.

Even if the attrition rate was 10,000 to one more in their favor under this type of scenario the numbers are going to tell them they are on the losing end of the deal and its time for an armistice.

OK, so following your response -

The problem is that your question falls into the 'how long is a peace of string' category. There are simply to many unknown variables. e.g. How much more technically advanced than us are they and in what specific fields. What types of weapons did they bring with them and how many. Failing that what can they make/jury rig once they arrive. Same for soldiers, how many what type?

Remember as I said, technically even a very small team of aliens could de-orbit asteroids of any size needed for a specific purpose and drop in on our heads. No other weapon needed. Indeed That might be their 'go to' technique for taking out key targets and softening up an LZ.

But...when the ground/air fighting starts its hard to answer your question without some description of the forces at their disposal.

So in the absence of answers to that kind of question I think the best answer might be small numbers of control and tech types sent down to the surface to run localized units of war robots. (It's all very good to have a giant 'command center' in the sky) but at some point after you land you need eyes & brains on the ground. People who can make split second decisions at close quarters for your platoons and companies etc of robots in real time.

This might especially be the case because they won't/don't understand us at first contact i.e. we're 'alien' to them. Fighting their own kind? - no problem their robots can probably be at least partially trusted with a degree autonomy about tactical issues . Fighting us though? that means re-programming their actions on the run. And you cant do that if you don't see what works and doesn't in real time.

So I would suggest everything goes well for our alien friends until we start to figure out how they operate and concentrate on identifying their local ground based command teams and spotters/observers when we can find them. They may try to withdraw them eventually and run everything from space but that just slows down the robots overall co-ordination and the tide slowly shifts.

They do the calcs and decide - again that its time for an armistice.

The plus to this idea as I see it is room for lots of discussion around small unit tactics, spoofing and deception, booby traps and ambushes etc.

  • $\begingroup$ I appreciate the effort. But my question is "So. What is their overall military capability have to be in order to attack us but actually fail in achieving their goals?" The rest is right thought. They have limited resources and they vastly overestimated their ability to ours. So they are engaged in war that followed the old advice: you can start a war anyway. But you can't always end that war. $\endgroup$ – Seallussus Jun 27 '20 at 3:39
  • $\begingroup$ I've amended my response. Check it out if you want to see if it helps. $\endgroup$ – Mon Jun 27 '20 at 4:45
  • $\begingroup$ why would they need ground or air forces, this is the same as America vs Japan during WW2 expect they can scale their nukes up to any size they want, have a near limitless supply, and we can't shoot down their bombers. they can force a surrender without ever using a single ground troop. $\endgroup$ – John Jun 27 '20 at 13:46
  • $\begingroup$ @Mon, Finally someone willing to actually help me solve the problem. It's all asteroids, they are better, just have them win. So far I'm the variables free because If I give them too much hoovering plasma tanks then they steamroll us and if I give them too little they don't attack. So I'm trying to find a reasonable balance and a general frame to start building this reasonably well. And if I start adding too much stuff cue complaining that it is too restrictive, even though that why we are all here, so hopefully someone will actually contribute to solving me problem $\endgroup$ – Seallussus Jun 27 '20 at 17:40
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    $\begingroup$ John, if the scenario involves them conquering Earth without Destroying the eco-system and all their potential slave labor then they absolutely need some form ground fighting capacity. As far as the Japan/WWII analogy goes - up and until the dropping of the A- Bombs the Japanese government had consistently refused to consider surrender. As a result the Allies were actively preparing for an invasion (Operation Downfall) which they predicted would cost the Allies millions of casualties. Fortunately Japan did surrender. In this case Humanity is not. So bombing us into submission is not an option $\endgroup$ – Mon Jun 28 '20 at 2:27

FTL is more or less the only tech they've got.


Yes, that's right. They're generally no more advanced than us, but for whatever reason they do have technology to relatively easily and safely travel between the stars. Maybe they stumbled upon it by random chance (some alchemist smashed just the right kinds of rocks together in a mortar to get FTL dust - Earth doesn't have these exact rocks or simply never tried that combination), maybe some pieces of tech from another alien civ fell on their moon or even were given by these other aliens - as an experiment, or as a gift, or for the lols - nobody knows. Either way, now all they gotta do is make some neatly sealed boxes with some air/other life support in and they can zoom across the galaxies with impunity. Depending on how handwavy the tech is, they may barely need things like navigation or shielding, or it is all part of the tech.

Anyway, this is more or less how this plays out then:

One day, alien ship(s) show up on Earth. They very quickly erase any doubt about their hostile intent, land in the middle of big cities and open their gates to unleash the invading armies of terror. Only they're armed with bows, brittle, heavy gladii and maybe a crappy prototype musket or two. Best case scenario some WW2 level tech.

After the initial shock (aliens!!) the terrestrial military shows up and steamrolls the entire invading party, possibly captures most of them alive for questioning and study, and seize enough bits of their ships to reverse engineer and get some FTL of our own.

Now, I might be awfully specific here, mostly because it is actully the premise of a classic sci-fi short story by Harry Turtledove called "The Road Not Taken". There, the invaders have easy, cheap FTL, but this actually stunted their tech development so the best weaponry they have is a flintlock.

  • 3
    $\begingroup$ On this topic, see the story "The Road Not Taken" (Question on scifi SE) $\endgroup$ – Ángel Jun 28 '20 at 0:40
  • $\begingroup$ You need more than just FTL to travel between the stars. For one: shielding to protect the ship from the high-speed impacts by interstellar and solar particles. (Even tiny things hurt a LOT when travelling at relativistic speeds.) And food recycling, etc, etc. $\endgroup$ – RonJohn Jun 29 '20 at 3:48
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    $\begingroup$ @RonJohn >Depending on how handwavy the tech is, they may barely need things like navigation or shielding, or it is all part of the tech. $\endgroup$ – htmlcoderexe Jul 1 '20 at 8:27

There isn't a believable one as long as it is a real war.

with the scenario you have laid out there is no reason the aliens over have tp put even a single one of their people in danger and they can can do any level of damage to us, up to and including extinction. They can easily force a surrender without a losing a single individual.

What is given

  1. They have multiple ships with intersteller and intrasteller travel.

And that is all they need to win, they don't need anything else. they can drop rocks of any size they want, with bomb level precision, endlessly until we surrender. There is nothing on our planet they need they cannot get easier from asteroids including munitions. If they can make it here they have solved the closed loop food problem, and they have engines efficient enough to mine asteroids until the sun burns out.

Worse, they also have high end automation and a large population we are told this , meaning you cannot even rely on unexplained shortages, because again they can get resources and build anything they want without ever entering our gravity well.

weaponizing asteroids is just a question of math and propulsion both of which they have in abundance. To use your analogy this is Japan attacking the US, IF japans has hundreds of thousands of free ICBM's and we have not yet invented aircraft.

The only ways they can even put themselves at risk are to do several things that are breathtakingly stupid, which is possible, but not believable.

One possibility you have is it was not a real war to begin with basically the initial attack was done by a splinter/terrorist group and the aliens are actually peaceful and they make a show of surrender as an apology. There is nothing we can do to force a surrender and it would be a show not an actual surrender.

The only way we can win a war is if there was never a real war to begin with.

  • $\begingroup$ I really respect a good discussion. But I'm only asking a specific question. This answer is basically ignoring everything and telling me: hey. It's stupid. Fine. It's the most stupid idea in the the world. Can we move on and try to solve this particular problem? Also you have no idea of how they solved any of their problems. There is much more that I have not said and won't say because this is NOT a place to drop the entire "lore" of the aliens to solve a simple problem. $\endgroup$ – Seallussus Jun 27 '20 at 17:28
  • $\begingroup$ @Seallussus Sometimes the answer to a a question is "no with the give parameters" the OP provided a set of conditions and asked a question and there just isn't a way to settle the two, physics and chemistry put solid restraints on how problems can be solved. Then what you do is point that out and try and show how to get as close as possible with the least number of changes which is what I did. I did not "drop any lore" other than what is already given in the question. $\endgroup$ – John Jun 28 '20 at 0:30
  • $\begingroup$ An answer below actually did provide a reasonable scenario of "changes" without any of your constant objections. And I can write you the actual backstory to most of these things with more limitations and then the question gets closed because I did nothing or added too much or it's a story set in a world or whatever. I appreciate wanting to show the world how the premise won't work. Seems like a noble goal. But if this is not a place to try to figure out a tough puzzle then just leave me to my own broken premise. $\endgroup$ – Seallussus Jun 28 '20 at 5:12
  • $\begingroup$ There are numerous examples of countries losing a war after the other country surrendered. Of course, the humans’ first step to end the bombarding from space, is to surrender. Then, the interesting story begins… $\endgroup$ – Holger Jun 28 '20 at 12:19
  • $\begingroup$ @Seallussus You're not "asking for discussion", you're demanding "please me by magically making 2+2 = 100500". $\endgroup$ – Oleg V. Volkov Jun 28 '20 at 12:46

Their lack of AI would deny them a huge advantage, in that they would not be able to effect the (arguably) easiest form of invasion and seizing control. With an AI they would never need a ship to invade. Instead, all they would need is some bandwidth to transmit it over. But since they don't like AI, they wouldn't actually be able to successfully invade as I could see.

In a planetary invasion the natives are at an overwhelming advantage over any would-be invader, due to sheer number of people in militaries (let alone the hordes of shotgun-armed Texans.) To actually invade a planet like Earth successfully, they would almost definitely need an army of at least ten billion personnel. I highly doubt your fleet would have that many people.

Alternatively, they could destabilize the world's governments through insurgency. This would be (relatively) simple: use social media to make a population discontent, and then use this as a jumping board to incite rebellion on a global scale. Wait until insurgent groups have established global anarchy, then have your aliens come as saviors. Do a global COIN campaign, then rise to power through humanity's own political process.

Takeover complete.

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    $\begingroup$ What reason could they have for completely abandoning a technology as incredibly useful as AI? Even if you say "they created self-aware AI that attacked them", that wouldn't prevent them from using current Earth-level AI which is not dangerous. $\endgroup$ – cowlinator Jun 26 '20 at 22:26
  • $\begingroup$ yes. which means they're denying themselves a good advantage in not using AI. $\endgroup$ – Mr. Anderson Jun 26 '20 at 23:19
  • $\begingroup$ Punctuation and capitalization, man! You Make Me Sic [sic]. $\endgroup$ – The Daleks Jun 26 '20 at 23:24
  • $\begingroup$ Yes, they are denying themselves a good advantage. Why? $\endgroup$ – cowlinator Jun 26 '20 at 23:26
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    $\begingroup$ They have more advanced computers and self driving tanks and drones. But not true AI. AI is fine and super fun. But I myself am NOT sure if it is even possible. afaik it's theoretical so far and until someone comes out and provides the world with an actual AI then I'll believe it. That discussion aside. We could argue endless possibilities from mind control to magic to engineering a disease they produce medicine for that needs to be taken constantly to reducing fertility in humans to a hundred other things. $\endgroup$ – Seallussus Jun 27 '20 at 0:19

They are not well-adapted to Earth

The aliens have higher technology, but earthlings are better adapted to the environment. Their home planet may have a lower gravity than ours (and the long journey on the low-gravity of a spaceship wouldn't help), our atmosphere may be toxic for your aliens, they may be susceptible to local bacteria and virii...

This can be worked around, but that gives humans an advantage. If they move slowly and need their space suits in working order, that makes light humans able to evade them, or even defeat them by damaging their suits.

You could imagine a cataphract knight battling against aztecs. The cataphract technolody (iron sword, horses, armour) is superior to actec technology, and just a few of them could decimate an army of actecs in battlefield. However, a knight is heavy, and requires supporting personnel (not available for your aliens). Enter on a forest, the aztecs could throw him from the horse (in which case he could barely stand up), prepare traps on the ground...

The best environment for the aliens is their own starship. However, placing it on a too-near orbit would risk it being damaged by Earth missiles (space is a bad place to be with a damaged ship and, if the invasion failed, they need their ship to safely go somewhere else), so they have it on a quasi-random route, only getting slightly nearer when sending/receiving a ship. On the other side, Earth would probably have automatic missiles "patrolling" the higher layers of the atmosphere, programmed to hit any object larger than X.

Also, trips to the ground (alien tanks, provisions, more soldiers...) are highly vulnerable while descending. There are only some angles suitable for re-entry, and there is a lot of kinetic energy to lose before landing. Yet, an ship-sized object entering the atmosphere is easily detectable. Re-entry becomes much more complicated if you additionally need to dodge the enemy bombs!

  • $\begingroup$ Remember that the Conquistadors did not defeat the Aztecs: the Conquistadors plus a lot of angry and oppressed other aborigines defeated the Aztecs! The aliens would need a divide and conquer strategy (which I'm dubious would succeed after they turn on one of their erstwhile partners; besides, all of the major Earth powers need each other economically). $\endgroup$ – RonJohn Jun 29 '20 at 3:39

It seems your after a military capability 'number', that's high enough to justify starting the war but low enough for loosing. Warfare has so many unknowns and huge mental components that other answers discuses in detail. It is misjudging morale, political will, tactical skill, ruses, sabotage, second/third/fourth order effects on actions that make it hard to judge military ability. It entirely possible to misjudge combat ability that isn't revealed until the war starts.

So. What is their overall military capability have to be in order to attack us but actually fail in achieving their goals?

I think all they need a low risk option they believe will be available no matter what. Like ability to strike from space, without interference. So long as they can hit big targets without risk, you would assume they always had a fall back tactic.

All drone based invasion is a risk, even if they are all destroyed, you can still have your space battleship bombing cities you can always retreat.

They knew all along they may never win total victory (because they are sound tacticians who understand they lacked details about earth), that maybe they had to settle a deal after constant orbital bombardment, but they could have ALWAYS retreated and moved on if needed. How is this not worth rolling the dice on?

*I think its also false to assume settling a preferential peace deal means a loss, and not a victory.

  • $\begingroup$ "Like ability to strike from space, without interference" Exactly. So far humans can target their own ships. The entire land operation is a low risk attack that just tests the water. And I'm trying to figure out a reasonable scenario to handle the first stage without having them dropping a billion nukes on earth and fin. People are raving about the premise but this is merely my first stage. And if I dared ask a broader question about the war it will get closed. So I'm limiting the questions. $\endgroup$ – Seallussus Jun 28 '20 at 4:37

Whatever tech they have, they should have very serious issues with it

If a fighting force is capable of interstellar travel, them failing achieving military goals (against militaries of Earth) does not sound credible at all. That is unless something is seriously wrong.

The possibilities could be:

  • alien force is in a very bad shape at the point of arrival. This may be beacuse they had to fight their way out of their home state and now most of their equipment is severly damaged/unusable
  • alien force is not a fighting force per se. They are paramilitaries mostly armed with small arms and no (or very limited) access to heavy equipment. Or maybe they are not militarised at all - their flet could be a resource extraction and colonisation fleet, not equiped to fight at all and all weapons they possess are converted from some civilian tools and vehicles

It sounds to me that whatever option you go for, in order to botch the invasion, aliens must be unable to maintain air(and space) superriority. Given that - Earth militaries have a chance.

ANY tech + Inability to capitalise on initial success

If you want aliens to to be proper fighters with tons of hardware, the only scenario I can suggest is the initial success of milatry campain but a subsequent failure of occupation for reasons unrelated to pure military might. Aliens may have miscalculated in evaluation of their supply chain and are unable to establish/maintain/protect their manufacturing facilities on Earth. This coincides with lack of manpower to succesfully maintain occupation and eventually they are forced to negotiate..

Lust for battle

Lastly, it sounds like your aliens should be very bloodthirsty to proceed with the invasion. Your stated goal of getting a chucnk of space for themselves could be achived through alternative means:

  • coercion: "give us this, or we will drop an asteroid on you"
  • trade: they may establish a corporation manufacturing consumer goods using their secret tech and be quite successful in embedding themselves into global economy, using the profits for establishing gated communities in paradise-like spots for alien elites
  • cooperation: they can help solve some of our issues related to arable land, turning deserts into farmaland and forsets keeping a small areas for themselves as a 'fee'

Why wouldn't they want to do any of the above? The answer should provide an irrational reason - religion/tradition/etc.


The only way this type of force could conceivably fail would be failure of political will. They may have assumed that they could win by killing a few million humans (which they can do with impunity, being able to strike from way beyond the reach of our weapons); then they find that they have to kills tens or hundreds of millions. The slaughter is eventually too much even for them. What are their news media like?

Or, if you want to go the allegorical route, they easily defeat the Earth's combined militaries, but then have prolonged actions by human terrorists chipping away at them and their human proxies. The humans only kill a few aliens a year, and millions of humans are killed, but again the aliens political will fails and they get fed up with this interminable, unwinnable war. They eventually pull out of Iraq/Afghanistan/Earth.


Another possibility: They don't actually have their tech. Your aliens original purpose wasn't invading Earth. Rather, this is an enemy warship that is seriously damaged by some means. It expends the last of it's maneuvering capability to attain solar capture at something like Earth's orbit. All that's left are strike craft with energy weapons and shuttlecraft, both of which don't have much more life support range than needed to reach Earth during a conjunction. Their objective is to make us submit to supply what they need to fix their ship, but they are set up for space warfare, not invasion. They can do damage while the conjunction lasts but then have to wait years for the next one, when they come back they get a very hot reception.

  • $\begingroup$ In that scenario, "make us submit" is quite foolish, and they would know it. TRADE would succeed, though. $\endgroup$ – RonJohn Jun 29 '20 at 3:41
  • $\begingroup$ @RonJohn It's a big bluff, not actually foolish. It's like Hiroshima/Nagasaki--a giant bluff that worked in getting Japan to submit. It was a bluff, though--we couldn't maintain the bombardment. $\endgroup$ – Loren Pechtel Jul 2 '20 at 0:01
  • $\begingroup$ The difference is that we actually did nuke Hiroshima and Nagasaki, and were ready to drop another Fat Man ten days later, if Japan hadn't surrendered. The whole Manhattan Project was designed to make three Fat Man bombs per month. $\endgroup$ – RonJohn Jul 3 '20 at 5:51
  • $\begingroup$ @RonJohn It was going to be quite a while before we could turn out enough bombs too actually finish Japan off. It was a great bluff. $\endgroup$ – Loren Pechtel Jul 4 '20 at 4:24
  • $\begingroup$ If by "finish (them) off" you mean nuking every square inch of the country, then... yes, it would take a good long while. But at three per month you've wiped out Tokyo and the main military base and shipyard not in Tokyo by early September. Then start on areas near the landing beaches. $\endgroup$ – RonJohn Jul 5 '20 at 6:08

Their strategy relies on alliances. Which fall apart.

Like you say, they find an Earth that is fractious. So they identify terrestrial powers that have a big enough military to succeed with support, and a government that is either

  • unprincipled and opportunistic enough to ally with the aliens for their own world domination (Saddam, or perhaps the Russians), or
  • ideologically principled in a way the aliens claim to be aligned with (China, EU, US).

This then fractures, because the aliens don’t plan to keep their promises of power sharing, and/or turn out to be not so well aligned with values after all.

Their ally figures this out, possibly because the other nations convince them of this diplomatically.

They then do a heel-face turn, taking advantage of their integration with alien forces to “catch them completely off-guard”.

Partly for cultural reasons, the aliens do not see this coming.

  • $\begingroup$ Interesting. Problem is how is it played? Either that nation actually allies with the aliens in which case I can see a lot of trouble. Or if they pretend then the aliens will wonder why they are NOT having a lot of trouble. So what do you propose? Personally it might need to change. A group of "anti" humans join the aliens and kill a bunch of humans. They are treated with disrespect and doubt until they gain access to maybe an alien ship and blow it up. That would be an epic espionage operation $\endgroup$ – Seallussus Jun 28 '20 at 20:13

Why bother with earth in the first place?

War is messy, and even if you win, some of your ships might be damaged beyond repair.

they detest manual labor and actually fighting.

If they detest manual labor and fighting, why in God's name are they fighting instead of negotiating? "You give us what we want, and we'll give you what you want."


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