I've lately been looking at a lot of War of the Worlds remakes/spinoffs, like the 2005 film, the 2013 mockumentary The Great Martian War, and of course, the tabletop game All Quiet on the Martian Front. While looking through all these awesome stories and scenarios, one question has been bugging me for a while.

Why exactly ARE the Martians invading?

(This is not a question about the novel/movies/etc. It's a question about Martian invasions such as the one depicted in this story. Why would they do that?)

Before I get into my qualms, lemme present you with some research I've done. The original story was initially written in the late 1800's-early 1900's, by the brilliant H. G. Wells himself, as a commentary(?) on the imperialistic mindset of certain countries at the time. In the year 1913 (which is roughly when the story could take place), the world was on the verge of war. Europe was growing more divided as Britain allied with France and Russia, and Germany partnered with Italy and Austria-Hungary. An arms race had begun, increasing European military spending by 50%, and the Ottoman Empire was fracturing more and more. All it needed was that one little push to send everyone biting and kicking each other.

Now back to War of the Worlds.

In all the sources I'm finding, the reasons for the invasion don't pan out, or at least seem pretty dumb. Several play with the idea that the Martians are harvesting humans for food. However, as we all know, they die off from Earthly diseases, so collecting humans which are full of Earthly germs would be kinda dumb; after all, who knows if humans are safe to eat if they live on another planet? Obviously, this sounds more like a paranoid xenophobic fear than a realistic cause for War.

The mockumentary (spoiler alert) played with the idea that the Martians wanted to collect the metal and resources humans had put into their military, and used the war as a means to collect. But there are plenty of better sources of metal in the solar system. Heck, the asteroid belt's right there, open for harvesting, and it won't try and shoot you back. So no dice there either.

And as for the Martians being afraid of human destructiveness, keep in mind that this was the early 1900's. The first atomic bombs wouldn't be tested for another 20-30 years, and airplanes weren't even a thing until just a couple years ago. So what would a couple million humans do to Martians which already had HEAT RAYS AND INTERPLANETARY TRAVEL down pat?

So I now ask you...what WERE the Martians thinking? Empires only expand because of good reasons, whether food, resources, the completionist tendency to fill in all the empty spaces in a coloring book, or something.
What would prompt aliens from a desert world like Mars to send a dozen or so War machines on what would likely be a one-way trip to another world - a world with a radically different biosphere and gravity, mind you - and then start attacking the native population?

  • $\begingroup$ Re "The original story was initially written ... as a commentary(?) on the imperialistic mindset...": Who says this, and why do they think so? It's been a while since I read the book, but if memory serves any such 'commentary' has been reverse-engineered by academics who apparently think the only reason for writing must be social criticism, rather than the desire of the author to pay the bills. $\endgroup$
    – jamesqf
    Nov 16, 2016 at 4:19
  • 5
    $\begingroup$ @jamesqf "Who says this, and why do they think so?" HG wells himself, that's who. HG & his brother Frank were discussing the plight of Tasmanian aborigines which was pretty dire. Frank said something like what if creatures from another came down and did this to us? The book's dedication reads: "To My brother Frank Wells, this rendering of his idea". No reverse-engineering at all. Wells wrote both for social criticism and to pay the bills. Many writers do both. Also, p. 5, WotW: "The Tasmanians in spite of their human likeness were entirely swept out of existence in a war of extermination $\endgroup$
    – a4android
    Nov 16, 2016 at 5:30
  • $\begingroup$ [continues] -- waged by European immigrants in the space of fifty years. Are we such apostles of mercy to complain if the Martians warred in the same spirit." As an interesting irony, "The War of the Worlds" was originally published during the celebration of Queen Victoria's Jubilee, the summit of British Empire, and was a metaphorical boot up its backside. $\endgroup$
    – a4android
    Nov 16, 2016 at 5:39
  • 1
    $\begingroup$ I think this question might be a better fit for the Sci-Fi Stack Exchange. $\endgroup$ Nov 16, 2016 at 11:01
  • $\begingroup$ @a4android: And how does using an interesting plot device derived from history turn the book into political commentary? In that case, every Harlequin romance with a historical setting qualifies :-) $\endgroup$
    – jamesqf
    Nov 19, 2016 at 4:47

13 Answers 13


It is worth revisiting the vision of the universe as seen in the late nineteenth century when Wells wrote The War of the Worlds (1898). In that view the planets of the solar system formed from a cloud of gas and dust. This is the so-called Laplacian nebula hypothesis, not unsurprisingly formulated by the Comte de Laplace, mathematician and astronomer, it postulated that the planets condensed out of the nebula, with the outer planets forming first. This means that the inner planets formed last.

So the further you go out from the Sun the older are the planets. Mars by this reasoning is older than Earth.** Using this cosmological framework Wells speculated that Mars is much older, growing colder, its resources running out, and all in all it is a dying planet. The canny Martians finding their home planet is going to wrack and ruin decide to dispatch an invasion force to seize the Earth by superior technological force and make it the new abode for Martian life and intelligence.

As a side-note: Because Wells had studied science, in particular zoology, he took pains to make his Martians non-human creatures unlike other writers of imaginative romances who were his contemporaries. Although Wells wrote a speculative article called "Man of the Year Million" which suggested our far-future descendants might become creatures that were not too dissimilar to his Martians. There is more than a hint that the Martians are what we will become, and despite the better technology they weren't much improved ethically.

The dying planet rationale is often used to justify alien invasions by science-fiction writers. This is a big improvement over writers who seem think coming to steal all our water would be a great idea for an invasion.

The purpose of this answer is to show what was the reason within the conceptual framework of the late nineteenth century that prompted and shaped the way HG Wells wrote about a Martian invasion. His novel reflects the science and politics of his day.

**: Also, Venus was considered in the Laplacian model to be a much younger planet than Earth. This the reason why the planet Venus was often portrayed in early to mid-twentieth century science-fiction as a world of primeval swamps, jungles and dinosaur-like monsters. Basically as an exotic version of the prehistoric Earth.

  • 6
    $\begingroup$ "Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us." Everything in "The War of the Worlds" is as scientifically accurate as Wells could make it based on the understanding and knowledge of the day. While science marches on, the continuing power of the book is its moral and ethical observations about the Human Beings, not the Martians. $\endgroup$
    – Thucydides
    Nov 16, 2016 at 6:49
  • $\begingroup$ @Thucydides Quite so, but the Martians mirror aspects of human nature too, which does keep the novel's proper focus on the moral and ethical behaviour on human beings. Wells was a good author, which is why his fiction is still alive today. Not all of his fiction, alas, but his scientific romances retain their vitality and accessibility. $\endgroup$
    – a4android
    Nov 16, 2016 at 7:51
  • $\begingroup$ As I recall, not only does the beginning portray Mars as old, worn out and cooling down - leading the Martians to try to extend their society by conquering the warmer, less developed Earth - I think it also ends with the parallel vision that when Earth eventually runs down and cools, humans will look towards Venus for the same reason...only humankind will triumph in the same way humans conquered the (common, earthly) diseases that had killed the Martians, proving humankind the fittest of all and thus triumphant! I remember that part of the ending because the logic made me roll my eyes. $\endgroup$
    – Megha
    Dec 16, 2016 at 3:27
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    $\begingroup$ @Megha You're right about the beginning of the novel. It is suggested the Martians may have invaded Venus too, and possibly successfully.Yes, there is speculation about humans trying to conquer Venus at the same time in the future, but it concludes with the question whether the future belongs to humans or to the Martians. There is a hint other dangers may come from space. Wells wasn't a human triumphalist, he had learned the lesson of Darwinian evolution too well. $\endgroup$
    – a4android
    Dec 16, 2016 at 6:48

They need the planet ready for colonization as soon as possible.

Back when the 2005 War of the Worlds film came out, a friend and I tried to puzzle out a reason for why the aliens (not going to call them Martians, as they apparently were not Martians in that film) behaved as they did, and what we came up with was the following:

Tens to hundreds of thousand of years in the past, the aliens scouted Earth for eventual terraforming and colonization. THey seeded their construction equipment, designed their biological components of their terraforming technologies, and got ready to begin altering the planet to their specifications... and decided not to. Perhaps funding, or political will, or something else ran out, or perhaps they got involved in an interstellar conflict with another species. For whatever reason, they decided not to go through with it, but left things in place so that they could be reactivated if the need arose.

Cut to some time before the invasion. Something has gone terribly, horribly wrong for the aliens in question. It could be that the interstellar conflict has gone much worse for the aliens than they expected. The aliens that come to Earth are refugees, fleeing some kind of disaster, political, natural, or interstellar. Or maybe it's just a poorly-organization trying to make a relatively-quick profit. At any rate, they need a new planet, and they need one ASAP, and they don't have the resources to do everything properly. Someone remembers the records of the Earth project, and they look it up: The terraforming machines are already in place; the biologicals have already been designed. All we need to do is port a few scientists in to get things started and...

Damn, there's a technological intelligent species already there.

Okay, we can deal with this. We'll jury-rig the construction equipment into war machines and send the tripods after them. The landscaping rays will work fairly well against their primitive technology, and once we've killed them all, we can seed our biologicals and start reworking the biosphere and...

Damn, the Red Weed is not working properly. It was designed tens of thousands of years ago, for a different environment, and to be tended by a full complement of skilled ecoengineers. We can't completely redesign it, it would take too long.

Okay, we can work with that too. We don't have all the knowledge and expertise we had back when the project was initially planned, but we've got some texts and we should be able to jury-rig its genome so that it can thrive on the Earth that is instead of the Earth that was. Also, since we're going to have to kill all these humans anyway, we can use them as biological feedstock once we manage to tweak the Red weed enough to --

Damn. Tweaking the Red Weed to run off human feedstock allowed a native pathogen that evolved since our last surveys to interact with the Red-Weed genome and turned one of the symbiotic viroids that were in the Red Weed into a contaigion. Once we would have spotted by the full complement of ecoengineers we don't have, or by the ones we did have, if they'd had more time to do their job properly. And now it's gotten into all the foodstocks, and infected the entire advance party, and they'll be dead in cycles.

This was a fiasco. Quarantine the world, and check on how things are going on the other abandoned terraforming projects.

  • $\begingroup$ I like the way you guys wrote this one. Lol $\endgroup$ Nov 19, 2016 at 3:43
  • $\begingroup$ Surely the most original interpretation of War of the Worlds I have ever seen. Upvoted for thinking outside the box. $\endgroup$ Nov 22, 2016 at 16:30
  • $\begingroup$ I keep thinking about this scenario: the Martians as half-smart, desperate players with a scheme that cant fail. Notovny, where are you?? Come back! $\endgroup$
    – Willk
    Jun 2, 2018 at 18:34

They're here because of massive, global climate change on Mars.

It's possible that the Tharsis Mountains on Mars used to emit massive amounts of H2O and CO2 into the Martian atmosphere, potentially even covering nearly the entire planet in over 100 meters of water. But, the volcanoes are much less active now, and the water doesn't have a proper water cycle like on Earth. So, the Martians have been slowly retreating with the poles, following the small remaining amount of water as their world slowly becomes inhospitable to them.

But, they're certainly not technologically inactive. Oh, no. They've got a space program with one single goal: fly to Earth and forcefully colonize it. We're even making it more attractive to them by increasing CO2 atmospheric concentrations. As soon as they get here, they'll probably start burning down the jungles to accelerate atmospheric CO2 increases.

And, of course, you can't let those monkeys with delusions of grandeur ruin your plans. So blast their population centers until there's only small pockets of resistance remaining.


Assume that the planet Mars is an abode for intelligent life and it has an ancient civilization. Resources are sparse, the temperature low, the atmosphere is pretty thin, and the surface is uninhabitable. Recently probes from the third planet have arrived on the surface and in orbit around their home world.

The Martians have had interplanetary travel for millennia. Their laser technology and portable power generators make formidable weapons. Nuclear weapons are easy too. Do these humans represent a threat to the Martian way of life and peaceful interspecies coexistence? Of course, they do!

Consider this, Earth is a planet dominated by a species of primate whose social and political institutions are mainly mobilized to wage large-scale organized conflict. They are on the verge of developing interplanetary travel. Yes they have lasers, but these are far from weapons-grade laser systems. Their nuclear weapons technology is a potential threat. Their global culture is one of runaway resource consumption. Soon they will the invade the solar system and begin strip-mining asteroids and establishing settlements on its moons and planets.

Earth is the fifth biggest planet in the solar system. That's right, Earth is a giant planet solar system wise. The Martians do not visit Earth because of its high gravity. Earthlings, once they have sufficiently developed interplanetary travel, will be able to access all the planets in the solar system with the exceptions of the gas giants.

This means Earth and Mars may find themselves in competition for resources and living space on the moons, asteroids, and planets. Earthlings will be able to occupy and visit Mars while the Martians won't be able to do the same on earth.

Admittedly the Martians will have developed a mature environmental friendly technological culture many, many millennia ago. Now they are threatened by a cancerous incursion into their civilized and highly cultured solar system by primitive tribes of under-educated apes.

The Martians are not fools. They know their biology. This is evolutionary competition. The Darwinian struggle writ large between technological species from two different planets who will now be competing for the same set of resources.

They will "slowly and surely draw their plans against us." This is a war for survival. Them or us.

Two sapient species with interplanetary capable technologies cannot survive together in the same solar system unless they have both learnt the art and science of mutual cooperation and tolerance across species. Each species will have weapons and technology that can exterminate the other. If the species with the technological advantage truly feared and felt threatened to the point that it might be extinguished by its potential adversary, then the temptation to strike first could become irresistible. In which case, let the Martian invasion commence! May the better species win!

PS: Wells' Martians were the product of the late nineteenth century, these early twenty-first Martians will have superior physical and biological technology. No microbe, no matter how humble, will lay low these Martians. Also, gravity was no obstacle in 1898, the Martians wore their Fighting and Handling Machines like mechanical exoskeletons now with AI upgrades and better telemetry Martian Fighting Machines can be partially controlled and directed from orbit, allowing the Tripods themselves to do the rest with local decisions.


Empires don't have to invade for external reasons. Their own momentum and the need to employ their military assets can be a reason in itself.

The Romans didn't always need to keep expanding, and they conquered peoples who were absolutely no threat to them. One of the reasons they did this was to employ their military and gain glory for elites. So quite often they picked fights for no better reason than that.

Timur-i-Leng did the same, he went on an uninterrupted cavalcade of victorious conquest for no better reason than to employ his army. Ghengis Khan picked fights wherever he could, his descendants unsuccessfully invaded Japan twice for no other reason than because it was there and unconquered. Alexander the Great was pretty much the same, he'd beaten everyone at home, so he headed abroad. Cyrus the Great, Phyrris and uncountable Asiatic, Middle Eastern, African, South East Asian, Amerind and even Polynesian outfits did the same.

Many of them even massacred populations who hadn't resisted.


We've all seen multiple films where the "evil aliens" want to steal <natural resource> from earth, and I agree, it's an absurd premise when you can readily collect them from a shallower gravity well someplace else. I suspect that most empire building objectives, while realistic when Wells wrote the original, would seem equally silly in the light of modern scientific knowledge.

One possible justification for war, however, might be as a first strike to prevent us from invading them. Consider:

  • Le voyage dans la lune came out as a film in 1902, and Aelita: Queen of Mars came out in 1924. We didn't have the ability to transmit them electronically, but perhaps the Martians' sent an Earth probe to secretly collect data, and it pulled a copy of the film. They might believe it was a documentary, and think we already had space travel.
  • Earth seems to have been in a perpetual state of war for centuries; it seems likely that any rational species would be concerned about what we'd do. Early SF horror or dystopian films might be scary, but historical films (e.g. Battleship Potemkin and The Big Parade depict how inhuman those earth people can really be.
  • Photographs of early cannons might be misinterpreted to indicate a massive space race already underway. The fact that they can't see us doing it might even be misinterpreted as "stealth" capability -- and the enemy you can't see is often scarier than the one you can.

If you want to stay close to the original H.G. Wells story, however, you may (spoiler alert) need to consider that the Martians' understanding of biology is substantially inferior to their understanding of physics. How can they travel in space and not be able to maintain biological isolation once they get here? Clearly they didn't think it might be necessary. General naiveté (as used to justify the points above) might suffice, but we might also be warring against a culture that has just come out of a scientific dark age of some sort.


If I were to theorize I would say that it would most likely be due to a couple things.

  1. Martians had known of us for a long time and always planned on cleansing the planet. They had never gotten around to exterminating us, then they saw signs of early technology that might give us potential to discover and kill them.

  2. A regime either governmentally or religiously that was in favor of leaving earth alone changing due to increasing fear that the earthlings would rise to power and "come for us next, once they get bored of killing each other"

Beyond that I would say it is pretty subjective. I haven't seen all of the versions, but as far as I can remember, I don't recall themselves ever declaring that Mars was their home. I feel as though it could be entirely possible they are from somewhere else entirely and stumbled upon this planet rich with resources.

The hard part is, we cannot really know what drives them. There are so many illogical things humans do that make no sense when you are an outside observer, but introspectively and evolutionarily they make perfect sense.

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    $\begingroup$ Welcome to Worldbuilding SE. I disagree that things that don't make sense as an outside observer would make sense evolutionarily. We observe evolution of other species from the outside and it makes near perfect sense. $\endgroup$
    – Zxyrra
    Nov 16, 2016 at 3:12
  • $\begingroup$ I meant the term outsider as being a point of view without that detailed knowledge of the ins and outs of an organism. By merely observing, you couldnt be sure what is an evolutionary trait, and what is a cultural trait without generations and generations of observation In some small way, everything we do is evolutionarily related, but If I wash my hands, is that evolutionarily?Yes because my brain decides washing my hands is good for health, but I was in no way instinctively conditioned to wash them, I decided to. How would a complete outsider know the difference? $\endgroup$
    – Dthorpe
    Nov 16, 2016 at 4:29
  • $\begingroup$ Sorry I would have edited my previous one, but I dont see an edit button, I meant how would they know the difference without in depth and lengthy observation? Now I wasnt saying they wouldnt do that with us, but that we wouldnt have had the opportunity to do that with them, therefore we wouldnt likely be able to tell from within minutes or even hours of interaction what actions of theirs were insctictive versus chosen. $\endgroup$
    – Dthorpe
    Nov 16, 2016 at 4:33
  • $\begingroup$ The edit button may have expired if too much time passed. That answer helps clarify, thanks. $\endgroup$
    – Zxyrra
    Nov 16, 2016 at 4:46

The biggest valuable thing on Earth is work labour. If you can harness that, you have really big basement for nearly anything. Same principle was after a lot of wars here on Earth. Also the same is why we domesticate animals. Basically...


If they can manage to rule us, they will have really big source of energy, work and we will be "self-servicing" damaged "parts" of the system by new babies. All needed is just to collect the revenues.

Then there are another considerations, as "just get resources", or eliminating us as a threat. Or they just had a bad day.


The 1950's movie starts with a voice-over that explains the Martians have been watching us from afar and are envious of us. Clearly they aren't envious of our technology or culture since they treat both with disdain. That also makes it unlikely they were afraid of us (not even of nuclear weapons). That basically leaves our planet or resources as their goal.

Since Mars is a barren desert that's not far-fetched which only leaves the question of which resources they are envious of.

It can't be something abundant on Mars, in space, or on other planets or moons since they have access to those places already. That really just leaves rare earth minerals, air, water, biological materials or environmental factors.

I would presume then that they intended to terraform (as in the unmentionable 2005 movie version), farm or otherwise harvest our biological resources. Whether they planned to do that themselves or use humans as plantation slaves is unknowable.

  • $\begingroup$ The voice-over is based on Wells' original novel. Mars is a dying planet, while ours is rich for the picking if you have advanced enough military technology -- and the Martians do! $\endgroup$
    – a4android
    Feb 16, 2017 at 6:40

Reason 1:

Their technology is advanced but not THAT advanced. They have vastly superior military resources but their replicator technology hasn't really taken off and they need large amounts of biomass to turn to food if they want their race to survive the coming century.

Reason 2:

They don't really need to invade the whole planet but only a small part. But they have monitored us and know that an invader would be what finally unites the humans. So they need to invade us globally and quickly to prevent an effective counter attack.

Reason 3:

They have been monitoring our progress and fear we might become the superior power in the Solar System/Galaxy. So they nip us in the bud.


Why posit aliens are always doing things for intelligent reasons?

Maybe they're religious fanatics. Maybe their leadership needs to divert attention to an external threat to distract from their internal issues. Maybe they're violent xenophobes and this seems like a good idea to the general populace.

Many of our own wars, including by the more powerful sides, are driven by terrible decisions (usually with business or industry on the side figuring out the best way to cash in, albeit for themselves, even when you look at the total gain/loss being a bad deal).

The biggest limit to this when it comes to space is practicality, which mostly depends on hard sci-fi premises. If you go with the soft science fiction rules around most alien invasion narratives, which make it, honestly, not much harder than any other invasion and conquest, yeah, it will happen for about the same level of reasons.


Martians were divided into many fractions hostile to each other. The martian leaders were desperately trying to find a way to pacify Mars. Of course historically the best way to unite your own people was always to have a common external enemy, but where to find that if you tried to unite the complete planet?

Finally they found the solution: Their astronomers reported that an intelligent race on Earth was starting to develop technology. That made those Earthlings a suitable target of spreading fear about: Surely they'd soon attack the Martians. Well, OK, realistically, they'd need another couple of centuries until they could even think of that, but hey, the Martian masses don't need to know this. So the propaganda machines were ramped up, convincing all the Martians that humans were already preparing to invade Mars and kill all Martians. Some documentaries about wars on Earth were certainly helpful (especially recordings of the nuclear bombs), and when the Earthlings started to send probes to Mars (which fortunately could be manipulated so that they sent fake images of a dead planet back to Earth) this was used as great evidence that the invasion from Earth was bound to happen soon.

The tactics worked: All Martians soon stopped their hostilities against each other and started working together on their plan on a preemptive strike on earth. But of course they needed to have the common experience of a Martian victory over Earth in order to ensure that Mars would remain united even after the threat was gone. The Earth population of course would have to be exterminated, in order to keep under the rug that in reality they were far from able to attack Mars.

Well, as we know from the movies, that plan didn't quite work out at the end.


Martians like Humans probably don't need a reason to travel over a "large expanse" and try to colonize, exploit, rape, plunder whatever they find on the other side. And realize that even if they are just 100 years more advanced than us, they can kill us quicker than the conquistadors did to the native people across many different continents on Earth.

The Earth is a prize for any space warrior races, lots of resources, sexy women and bunch of idiots that keep fighting with each other instead of defending it.

Consider this, a spaceship with the equivalent of just 500 nuclear warheads detonated at 5000 feet over every major city would kill the vast majority of everyone on earth, would leave every nation governmentless and its people struggling to survive. In about 2 or 3 years the radiation, disease, and lack of food would kill 90 percent of everyone left. The actual radiation would subside very quickly. And the aliens would have a slightly used planet for their use without so much of a fight.

The big problem with all WOW and Independency day is that they assume that the aliens are like Americans and Russian in Afghanistan, having to come down to give us a fight. No, they are just going to nuke us from orbit. It would take a few hours to kill 50% of the people on Earth. No advanced technology needed.


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