While sitting alone in my room today contemplating life I came up with a simple question. How do zombies take over the world when we have armies?

Let's just take the US army alone. They fought in two world wars and came up victorious both times against armed men with rifles, explosives, tanks, helicopters. I know that zombies are quite different from normal human beings in that once you get bitten you become one of them and start to turn other people but I can imagine a single squad of soldiers armed with machine guns taking on at least 1000 zombies.

So what I am asking is if there is any rational explanation as to how the zombies can take over the world? For clarification purposes I am talking about a universe just like ours where people know what a zombie is and how to take it out. Also no super zombies or any of that, just plain simple walkers like those found in The Walking Dead.

P.S. Sorry for any grammar errors. I am not a native English speaker.

EDIT: The disease is only transmissible through bites.


11 Answers 11


So the zombie Genre has always been a logically flawed concept, this is just another chink the chain.

To even start to address this topic you have to make assertions like:

  • It is already in every country somehow
  • They're undead
  • Headshots are the only means to kill them

and you have to understand the tactics of zombies:

  • Ambush from ignorance: zombies can get a lot of people because people don't yet know there is a zombie epidemic going on. Like, if you see an injured guy on the road your first instinct is to alert the authorities and try and help the guy.

  • Ambush from empathy: after zombies have taken over lots of people invariably will have to make the choice between killing their loved one or not, while still not knowing whats going on. Imagine being a soldier and firing on little kids while not being informed. So even more get taken over. Thoughts like:

    • what if this disease is curable?
  • The swarm: in most zombie flicks it's rarely the lone zombie that gets the people. Instead it's usually a swarm of zombies.

Now as for how to take on the army:
If suddenly the plague appears out of nowhere, you have them succumbing left and right to the various ambushes. These people are, by the way, off duty soldiers and commanders, politicians. So soldier gets bitten, goes back to base for first aid, gets the medical personnel then swarms the barracks. All the while politicians and officers are getting turned so the chain of command becomes disorganized.
(This is why it was the Navy that came out on top in WWZ, because their active duty chain of command is safely at sea)

At this point it is statistically impossible for all military installations to have been crippled. However, they have to contend with the fact that armies are built to protect their citizenry and what do they do if they encounter an apparent survivor? [shoot the survivor, turn them away to certain death, or let them in...]
After that whittling you will have hoards of zombies swarming military installations. Most installations are protected by a chain link fence, maybe even a mine field. Then try making a head shot, on a moving target, under life or death circumstances, while not knowing whats going on, with a sketchy chain of command at best. Most soldiers aren't trained to make that kind of shot, let alone not all military rifles are designed with the necessary accuracy to make that kind of shot. That is after they expend a clip or more before they realize they need to shoot them in the head.

At this point you have very few military bases, most likely those in active war-zone. Now for example take an American base in Iraq. You may have been able to fend off the plague, but suddenly you are a foreign army in a hostile zone cut off from your nation/supply chain. Just because there's a zombie plague doesn't mean the natives suddenly love you.

Now that the majority of your military, air force, and questionable amounts of your navy have been converted. You are doubtfully left with any intact outfits.

  • How good are tanks, when they require special fuel and tank shells, maybe kill 10-15 a shot? At some point you will be stuck in a tin can out of fuel, out of ammo and surrounded by zombies.

  • How good is automatic fire if head shots are all that counts? Sure, a well placed 50.cal might be able to take out quite a swarm, but with city populations in the 100s of thousands, how long before they run out of ammo? (Remembering they are cut off.)

  • Aircraft especially are a logistical nightmare. You need a trained pilot in that aircraft, specialist mechanics to get it working, fuel, ordinance, someone to provide targeting (and the technicians working in that background to relay the coordinates to the pilot).

See, the achilles heel of any army is its supply lines. Once those are gone things become grim.

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    $\begingroup$ Tanks are awesome zombie killers as long as they have fuel. The phrase George Patton used was "grease the treads our tanks". Otherwise, your remarks about training is spot on. However, military doctrine for prepared defenses is up to the task, once the importance of head shots is realized. Barbed wire has been used for more than a century to slow down attackers and make them easy targets. The success of the zombies in "Walking Dead" is due entirely to the writers having godlike powers within the show. Among other things, the characters are, collectively, stupid. $\endgroup$ Jun 7, 2017 at 1:07
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    $\begingroup$ @WhatRoughBeast Collectively AND individually stupid. $\endgroup$
    – Antzi
    Jun 7, 2017 at 9:20
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    $\begingroup$ @nefas : Rabies have a long incubation time and an almost 100% infection rate if bitten. Every infected has a stage when they try to bite as many other animals or humans as possible. Still, it didn't manage to take over the world. $\endgroup$
    – vsz
    Jun 7, 2017 at 14:52
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    $\begingroup$ As an aside, military members are commonly taught the failure drill: Two in the chest, one in the head. Against non-supernatural zombies, especially if you have some sort of barrier (fencing, barbed wire, etc) to impede them -> Goodbye zombies. Essentially all modern rifles are accurate out to hundreds of meters... an average AK is accurate within ~6 inches at 100m. Finally, a properly placed machine gun (at about head height) could easily devastate a horde in short time, leaving a half dozen competent riflemen to clean up the shorter zombies. $\endgroup$ Jun 7, 2017 at 17:57
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    $\begingroup$ Even if head shots were required for the kill, a tank can still run over zombies to pop their heads better than a bullet could. No shells required. $\endgroup$
    – JWT
    Jun 7, 2017 at 20:22

In practice the army could wipe out any number of zombies like the ones in 'The Walking Dead'

You can basically enclose any killing field and entice them in with a loud speaker. In fact any industrial outfit with heavy machinery could do it just by digging trenches and putting a loudspeaker in the middle somewhere and the zombies would just walk over the edge and fall in, fill it quarter the way with petrol if you want and burn them, or even set fire to it and they'll walk in anyway.

In my forestry days I lived on many farms who had diggers that would make this easy with just one guy. So the engineering corps of an army wouldn't even blink at managing it. Use their weakness against them.

Then mop up the remainder with groups wearing bite proof body armour armed with sidearms and short swords or whatever weapon you want.

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    $\begingroup$ Why isn't this the accepted answer? People seem to believe that the military is utterly incompetent. Any engineer would come up with such a plan within an hour of figuring out what the situation is. Chain of command is not necessary when you have thousands of violently creative individuals with access to heavy machinery and automatic weapons. $\endgroup$
    – AndreiROM
    Jun 7, 2017 at 22:46
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    $\begingroup$ @AndreiROM Not incompetent, but for the most part ill-equipped... routinely buying from the cheapest bidder certainly has some disadvantages. When I compare my current (civil) outdoor gear to it's olive drab counterparts, some differences show :) But of course you are right, units are prepared to act both separated and combined... much better than, say, government agencies. $\endgroup$
    – jvb
    Jun 8, 2017 at 5:56
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    $\begingroup$ This +many times: Chain of command is not necessary when you have thousands of violently creative individuals with access to heavy machinery and automatic weapons. $\endgroup$ Jun 8, 2017 at 8:55
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    $\begingroup$ @jvb I wouldn't call any modern army ill-equipped... Crap equipment has a way of... getting broken, and replaced with something which isn't crap. When your life is on the line, crap isn't really acceptable, even from a cheapest bidder, especially in the modern world where every death is a PR disaster. $\endgroup$
    – hyde
    Jun 9, 2017 at 8:20
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    $\begingroup$ They could do it with shovels if they had to, pre-machinery armies built bridges, roads and diverted rivers, or just entice the zombies into a one way valley. It wouldn't take them much thought to find a suitable killing field. $\endgroup$
    – Kilisi
    Jun 9, 2017 at 9:02

The real answer is "it depends". Military forces are designed to be adaptable and come up with strategies and tactics against an intelligent opponent (there is an old military saying "the enemy gets a vote, too").

Anon has set the stage with a good answer, and there will indeed be a time where it is unclear what is going on and units may be overwhelmed by zombie infections from within or without. However, at some point the incredible truth finally becomes clear, and surviving units will be able to come up with some plans for action.

At its base, a zombie plague can and should be treated like any other outbreak of disease. Quarantine of infected people and areas, strict control of movement and delivery of medication if some form of anti-zombie vaccine is possible. The military members also can take heart in the fact that a virulent plague like the zombie outbreak will burn itself out in fairly short order. With areas quarantined and movement restricted, zombies will rapidly run out of new people to infect, and biologically speaking, the infected bodies will run out of energy once everyone who can be eaten is consumed, and themselves die.

Once an area has gone "cold", specialists can carefully enter and examine the area, and scouts and snipers move in to clear any remaining zombies. The dead will likely be burned to prevent pockets of disease breaking out in the rear area. The perimeter expands and is secured, and the cycle begins anew.

In many ways this also resembles the classic anti-insurgent tache d'huile strategy, but can also be considered a variation of the British "blockhouse" strategy used during the Boer War (tache d'huile dates back to the late 1800's, and the blockhouse strategy was used in the early 1900's, so it isn't like you have to invent anything new).

The greatest difficulty for the US military is the "force to space" ratio; even if every Active, Reserve and National Guard member is unaffected and working on the problem, there are far too few service members to effectively cover the Continental United States. What will happen instead is a drawn out campaign where soldiers using low tech gear like razor wire fencing and 12 gauge shotguns enclose areas to secure them, then wait until the next district is "cold", rinse and repeat. After a few months, the vast majority of the zombies will no longer be active, and the remaining areas of the United States not already quarantined will need to be systematically covered and disinfected. Once again, this will be slow and heavy work, especially if the logistical chain has been disrupted, but still doable.

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    $\begingroup$ This assumes rapid response to the outbreak. Which is likely why the zombie apocalypse would never happen. The OP's main question is "How do zombies take over the world when we have armies?" If rapid response is in play that defeats the first 2 tactics i listed thus snuffing out the plague relatively quickly. However if the plague were able to catch the world by surprise then it is reasonable that it could effectively isolate military outfits to the point of being ineffective as a modern military. $\endgroup$
    – anon
    Jun 7, 2017 at 0:23

I think in a lot of movies Zombies do not behave like they would in a real life setting. Anything that moves needs some source of energy, because of physics. So there can not be a single zombie reaching a military base like area 51 simply because it would starve/dehydrate/rot before it could get there.

Another thing to consider is that zombies basically work like supercharged humans (think of them like aggressive people without instincts to protect themselves), which means that three bullets to the chest would also kill it at least in the long run.

All in all this means no real life zombie outbreak could reach all strategic bases of a modern army, especially in some vast countries like Russia or the US.

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    $\begingroup$ Welcome to WorldBuilding! If you have a moment please take the tour and visit the help center to learn more about the site. Interesting points, but I would remove the first sentence. Your answer looks valid, but you can only comment once you reach 50 reputation. The first sentence gives the impression that you are just trying to trick your way aroung that limit and may easily lead people to flag your answer as "Not an answer - should be a comment" and delete it. Have fun! $\endgroup$
    – Secespitus
    Jun 7, 2017 at 10:39

Unfortunately I cannot comment so I decided to post my comment as an answer.

I just wanted to add, that if we now quickly build some robots to hep protect us from all sorts of injuries, the probability rate of a zombie apocalypse would decresase drastically, because up till now zombies are not able to infest machines. However, this could change in future scenarios.


And please keep in mind that we have all sorts of drones, and pattern detection algorithms that could easily detect the slurping movement of the walking dead. So fighting them would probably very easy for the military.

So it is very unlikely.

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    $\begingroup$ Given the average "logic" in zombie movies, I'd expect zombie bites to infect the robots with a computer virus. $\endgroup$
    – Peter
    Jun 7, 2017 at 14:17
  • $\begingroup$ See this comment $\endgroup$ Jun 8, 2017 at 17:53
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    $\begingroup$ Zombie robots is a hilarious notion $\endgroup$
    – Thucydides
    Jul 6, 2017 at 4:34

I play a lot of video games and have a pretty good understanding of basic tactics in unreasonable situations so I'll give you a tl:dr;

The militaries lose if they can't figure out how the zombies happen fast enough to take measure to protect the vital resources then need to kill or "cure" the zombies.

The zombies win if they can spread fast enough to get their numbers past some critical point; it's a really risky zerg rush. This critical point would need to be high enough to give the side of the zombies a serious numbers advantage - I'll guess 100 to 1 but 10 or 20 to one honestly might work depending on the people fighting -, keep everyone in a state of perpetual conflict, and allow the zombies to control enough space to force the military to destroy major chunks of infrastructure in any massive destruction tactic.

There are a lot of potential holes here, but it all comes down to how fast people can adapt to the zombies and figure out how they work. That's why the people in the walking dead come from a global culture without zombie lore. If the characters knew how zombies worked beforehand then different tactics would have been used and the world might not have collapsed at all honestly.

Keep in mind that modern society is not as well equipped to fight a plague as a world war. Ebola did far more damage than it should have. Now imagine people with Ebola violently wondering around trying to spread it. That's a bit of a problem.

  • $\begingroup$ Ebola did not reach the western word, or China. Come to think of it, a totalitarian regime like Stalinist Russia is the Perfect answer to how to solve zombies. $\endgroup$ Jun 8, 2017 at 9:00
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    $\begingroup$ The Walking Dead world not having anything zombie in their culture isn't something I had considered before. It explains why they do things that are seemingly clueless and will attract walkers, when all/most of us watching know it is a bad idea. Knowledge about what they are and how to kill them would be stronger than most weapons, and give people a much great fighting chance in our world. $\endgroup$ Jun 8, 2017 at 13:26
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    $\begingroup$ @Flummox ebola did actually reach the USA. A few people in Dallas who had been exposed to people exposed to it in Africa caught it. It wasn't a big deal and it wasn't a massive outbreak. It would be different if people were actively trying to infect people like zombies would. $\endgroup$
    – user32463
    Jun 8, 2017 at 20:55

Late to the party but for what it's worth I think "The Walking Dead" did a good job explaining it.

Basically, the initial spread is by airborne virus with long enough incubation period so that a large portion of the population is infected before symptoms appear. As the number of sick people increases, some of them die and turn into zombies, panic ensues and social order breaks down.

If it's just a modern army vs zombies, zombies don't stand a chance. Zombies don't use tools, don't coordinate strategy and are really dumb. Their cognitive functions are worse than those of an animal.


This greatly depends on what you "want" from zombies. Short/no incubation so people realize these are a trouble straight away + zombies that are slow and without using any tools => any reasonable modern army will easily kill them, though not fast enough to prevent total destruction of the place where the outbreak started (say a major city).


If you put the same setting in middle ages, you essentially have peasant revolts, just much worse - not all peasants joined revolts and zombies are tougher, so result would be very devastating.

Or give zombies ability to use tools like a normal person without any training. Secluded areas could be fine if proper measures are taken fast enough, but zombies should be able to ravage the rest. Grab a car, get somewhere, start biting people... True, news would spread faster than disease, but in the initial confusion disease could be all over the place.

Or give zombie disease X days incubation during which the infected person looks and acts normal except for the bites - then you can have just about everyone infected before anyone even realizes something is wrong.


The US army would not suffer a single casualty except for accidents maybe.

I feel like you are making a couple (as in 2) of mistakes here as in I don't think you fully understand the genre if you ask such questions.

1) Zombies in popular fiction have mostly been a metaphor. Humans turning into something the author thinks is bad and a couple of human beings try to survive in this new world as in not changing into what anyone else has become. It is a similar concept (not the same, it is just a similar idea) to what Sartre (and others) described in his books, a sudden realization what the world is or has become = zombie apocalypse. A concept like "army vs zombies" does not make any sense. There is no army vs humans changing. There is only people not infected yet by whatever. An army is vulnerable because the soldiers are vulnerable to becoming the enemy on their own through their own choices = giving up or becoming absorbed into the latest trend, not so much through fighting a literal battle and being bitten like rabies. Even if it is more or less just a social experiment (the walking dead series), the idea behind zombies is rarely "super monsters that kill everyone" and more just something that happened too quickly to prevent and people need to deal with it afterwards. The dude from the walking dead literally wakes up in a world that has changed.

2) There is zombie lore in any culture I am aware of. I would advice you to look at other zombies than those made up by Romero. Some European zombies for example did their evil work without ever leaving the grave. This would of course be much more effective vs an army. I don't know every single zombie lore in detail since this is not my genre, but I'm sure you will find more fitting stuff if you do some research.

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    $\begingroup$ The OP clearly states "just plain simple walkers like those found in The Walking Dead." This is part of the preconditions of the question, not something that invites you to assume very weird interpretations about zombies being metaphors or extending the issue to other things that would not be recognized as zombies by most people at all... $\endgroup$
    – AnoE
    Jun 7, 2017 at 21:09
  • $\begingroup$ @AnoE Very weird or basic ... well, I think it's the basics. Feel free to disagree, but I advice you to think about it for a second. What we think of Zombies right now is all just the result of those early movies and people stuck by it pretty close up until now. I think people need to know more about things in order to develop truly great new stuff. $\endgroup$
    – Raditz_35
    Jun 7, 2017 at 21:26
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    $\begingroup$ the point is that the OP asks a very specific question about a very specific type of zombie. Your answer has nothing whatsoever to do with the actual question asked. The voting is not only about agreeing/disagreeing, but about finding an answer fitting to the question at hand... I'm not on a zombie crusade here. :) $\endgroup$
    – AnoE
    Jun 7, 2017 at 21:36
  • $\begingroup$ @AnoE I answered the question in two ways. I stated that the zombies don't stand a chance (which is what most answers here do) and I stated that zombies do not need to fight like this and beating an army is accomplished differently in that genre. You might not find it useful, but my answer is very consistent with how any popular zombie medium is handling this issue - which is ironic given that I apparently chose a weird approach. As a bonus I gave a third option if there needs to be a physical confrontation. But feel free to disagree again ... if I agree I will edit $\endgroup$
    – Raditz_35
    Jun 7, 2017 at 22:10

I always thought the zombie setting, especially the slow, weak zombie setting, is just the part of the book/movie you have to suspend disbelief for the real story to unfold, because I fail to see how any modern army could fall beyond recovery from the zombie threat alone. I would say that usually, real enemies (and drama) in zombie settings come from people.

So, trying to answer your question, if some military fails once the threat is sufficiently understood, it's mostly because of "sane" people doing anything to get into the military safe zones. From politicians overriding security protocols for their own (or loved ones) sake, to mobs charging against entrances of well-defended military bases with trucks or their right-wing extremist neighbour's arsenal. But even that would hardly work against well isolated or well prepared bases, thus strengthening the requirement of the outbreak to appear in all countries and zones at the same time.

So the chance for all military to fail is that zombies, which after years of starvation and rot seem equally functional, can anyways win an attrition war over a world with a limited chain of supply and unable to adapt to a low-tech setting when hard-to-procure supplies deplete. But that could take much more time that usually portrayed in movies.

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    $\begingroup$ "it's mostly because..." well, that's what it's all about in Zombie stories - the initial mayhem overwhelms every normal institution and society, and by the time everybody realizes, it's too late, what with exponential growth etc. $\endgroup$
    – AnoE
    Jun 7, 2017 at 21:10

Zombies will take over the world by abuse of EEO laws and non-discriminatory policy. The zombie community will stand together in peaceful protest, and demand, "BRAINSSSS..." We as a society are in no position to deny this marginalized minority what they need to survive. Brains will be mandated to be on the menu in McDonalds and other restaurant chains, just like vegan or gluten-free foods.

Zombies will (rightfully, I say) demand an end to they oppression and prejudice inculcated by Day of the Dead, Return of the Living Dead, and other movies of this type. They will demand an equal opportunity. They will work their way into government, political, and even military positions; herein lies the answer to your question.

Once they have thus obtained these positions of superiority, they will command the strongest military and political forces on earth. They will leverage their power to take over the world. This form of attack is pretty much unstoppable.

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    $\begingroup$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review $\endgroup$
    – sphennings
    Jun 7, 2017 at 22:37
  • $\begingroup$ @sphennings yes, good point. I have thus changed my answer, and marked my previous obsolete. $\endgroup$
    – kmiklas
    Jun 8, 2017 at 3:55
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    $\begingroup$ Actually funny for some reason $\endgroup$
    – Hi0401
    Apr 7, 2023 at 13:54

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