Would a chainsaw be a practical weapon in the medieval ages where swords and bows were the their main armaments? How well would it do against swords and shields?

Disregarding the problem with fuel of course. Just go with one of those chainsaws that always show up with a suspicious hockey masked man.

If the chainsaws are not all that practical then what can be done to improve them?

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    $\begingroup$ Ignoring fuel leaves construction, spares and material. Whatever improvements you make to create you chainsaw can be applied more easily to swords. Not to mention, it requires your victim to effectively stand still and not wear metal armour. $\endgroup$ – nzaman Aug 10 '16 at 13:13
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    $\begingroup$ I think horror movies and video games about man using chainsaw slicing a zombie in half really influence a lot of writers. From what I'd gathered is that chainsaw is a rather heavy machine to carry around, think about to bring it to battlefield is just no. $\endgroup$ – Crestial Aug 10 '16 at 13:44
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    $\begingroup$ The best way to use chainsaws as a weapon is probably to cut down a tree on top of the enemy... (or, on a serious note, cut timber to build siege weapons) $\endgroup$ – Guran Aug 10 '16 at 14:25
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    $\begingroup$ Environmentalists sometimes "spike" trees. This is intended to deter lumberjacks from cutting because they fear being injured or killed when their chainsaw hits the metal. $\endgroup$ – erickson Aug 10 '16 at 15:11
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    $\begingroup$ Rule of Cool trumps any futile notion of realism or common sense. $\endgroup$ – hyde Aug 10 '16 at 16:57

18 Answers 18


To quote Miguel Valdespino on Quora about using them in combat...

Chainsaws make poor weapons. While they cause a lot of damage to the enemy, they suffer many problems as weapons.

  • They are poorly balanced for fighting and very heavy.
  • They require fuel or power to operate.
  • They are noisy.
  • A mistake can severely damage the wielder.
  • Parrying with it can cause chain failure.
  • Chain failure can injure the wielder.
  • Most failures make the chainsaw ineffective as a weapon.
  • They are only effective in melee fighting.

I'd like to especially highlight the points of failure. A sword's or pike's point of failure are breaking (somewhat unlikely) or (eventually) growing dull. A chainsaw has drastically more points of failure, and most of them far more likely to happen than the sword's or pike's points of failure.

So the first time the chainsaw jams on a sword or has the chain knocked/bent off the track you're going to have the world's most awkward club, and little more.

And even if indestructible, a wall of pikes (8' - 12') will keep attackers at bay far better than chainsaws, as the pikes are easier to manage, easier to use in formation, and have far better range.

Okay, But How Do We Make Them Better?

You'd need to find a way to increase the torque, increase the fuel efficiency, and reduce the weight.

You'll have to make the chains thicker, and provide a strong guard to keep them on-track despite the chaos of being used in combat.

You'll have to reduce the likelihood that they'll jam, or some very fast way to unjam them. Perhaps a switch to quickly reverse the direction of the chain would help.

You'll want to tip the blade in a material strong enough to cut through metal. There's not a great way of doing this, as typically this is done as a grinding wheel (which would be less effective against wood and flesh; construction cutting devices typically are built for-purpose because of this), but tool steel with cobalt is sometimes used.

Ideally one would increase the range while not increasing the weight. I'm not sure how you'd do this, though.

You'll want to include safeties so that if the chain does break it contains it as much as possible. Hopefully also a dead switch so if it's forced out of the soldier's hand back on him it won't injure him.

Even with all the above listed fixes (to degrees that I imagine would be reasonable if engineers took to the task for a few years), somebody trained with a sword seems like he'd be more effective in a 1-to-1 fight, and in formation I can't see any real use for them, being strictly realistic.

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    $\begingroup$ I like the expression "the world's most awkward club" $\endgroup$ – Rigop Aug 10 '16 at 13:30
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    $\begingroup$ @Sky I edited to add a "how to fix them" section. Despite all the modern technology that goes into a chainsaw (which honestly is no small measure, between the materials, concept, combustion engine, and simple engineering), they're not really good for combat, even against wooden-and-metal-band shields and lances. There's a reason bayonet-knives are still semi-widely used in armed forces today, but not powered blades. $\endgroup$ – Ranger Aug 10 '16 at 13:36
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    $\begingroup$ This covers pretty much all of it, I'd like to note that aside from engineering required to make one (and OP said to ignore fuel) chainsaws require a LOT of maintenance. Sharpening, tighten the chain, engine oil, bar and chain oil, etc. Moving parts require maintenance and a chainsaw is basically an axe with 10,000 moving parts. $\endgroup$ – Culyx Aug 10 '16 at 17:28
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    $\begingroup$ What about the tiny chainsaws on poles used for tree pruning? $\endgroup$ – Telastyn Aug 10 '16 at 18:21
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    $\begingroup$ Take a page from the Sharknado movies and make a lightsaber-chainsaw? $\endgroup$ – David Starkey Aug 10 '16 at 18:34

Would a chainsaw be a practical weapon in the medieval ages?

Hahahaha ... oh, wait. You're serious.

No, they would not be at all practical or effective. I mean .. they might scare some people, but have you ever used one? They would not be anyone's weapon of choice.

How well would it do against swords and shields?

Terribly. Block with the shield, stab with the sword. I am now the proud owner of a slightly used chainsaw.

If the chainsaws are not all that practical, then what can be done to improve them?

Nothing much. A chainsaw is a tool meant to simplify modern life, and optimize a process. That process is cutting down poor, defenseless, stationary, unarmored trees.

Mankind has had a lot of practice at optimizing killing tools, and the result was the semiautomatic carbine, not the chainsaw.

Believe it or not, swords, shields, and armor were very well thought out armaments, and the soldiers of the time would be experts in their use. A chainsaw would not cut through plate armor, would get stuck in chainmail, have a difficult time going through a gambeson (while the owner is stabbing you in the face), be cumbersome to wield, and generally is quite a finicky machine which requires spare parts, maintenance, and fuel. By comparison a sword is easy to use, light, and a damned bit more dangerous.

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    $\begingroup$ +1 for "Mankind has had a lot of practice at optimizing killing tools, and the result was the semiautomatic carbine, not the chainsaw." $\endgroup$ – scrwtp Aug 10 '16 at 19:52
  • $\begingroup$ yes and the sword is really easy to build and maintain as well $\endgroup$ – sdrawkcabdear Aug 11 '16 at 0:30
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    $\begingroup$ @selenog - you're right about standing armies, but wrong about soldier's training. There existed many bands of mercenary troops which were hired by one noble or another as the political landscape changed. So while no standing armies existed, there were many professional soldiers around, and you better believe that they were well trained by their respective officers. $\endgroup$ – AndreiROM Aug 11 '16 at 13:50
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    $\begingroup$ @AndreiROM True, my bad. I was talking more about the "cannon fodder" that made up the bulk of most armies, the common folk gathered for that battle/campaign. The nobles (=officers) where trained as well of course. $\endgroup$ – Selenog Aug 11 '16 at 17:12
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    $\begingroup$ @Luaan Axes for combat were not the same as axes used for chopping wood - quite different and contradictory attributes. I'm struggling to think what use a mace would be, and even while the flails used for war and the flails used for threshing had the same name, they were not the same item. While some truly impoverished people may have used farm tools to fight with, this would be only out of pure desperation and not part of equipping for battle. $\endgroup$ – pluckedkiwi Aug 12 '16 at 16:43

Nex Terren I believe is right, it's not feasible.

But if you were forced to use a chainsaw in a medieval battle I would recommend taking the chain and the arm off. Those break very easily in my experience. Now you have a heavy noisy metal box with two nice handles. If you got close enough you could bludgeon someone with it. To improve upon it add a long handle to it and use it as a mace or hammer.

  • $\begingroup$ Laughing. Out. Loud. $\endgroup$ – AndreiROM Aug 10 '16 at 13:53
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    $\begingroup$ The fuel might make a nice weapon! $\endgroup$ – BZN_DBer Aug 11 '16 at 19:51

Have you ever used a chainsaw? Unless you position it JUST right it jams or the chain comes off. Don't let that spoil your fun in a fantasy story though! Chainsaws are iconic. Enjoy them.

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    $\begingroup$ This answer actually has something that mine missed: If it's not very hard science fiction (assuming sci-fi for having modern tech in the past), then don't worry about it if it makes for a better story and better storytelling. $\endgroup$ – Ranger Aug 10 '16 at 14:52
  • $\begingroup$ And if you touch with the tip, it kicks back at you ... which either really messes up your day, or triggers the safety which stops the blade. $\endgroup$ – Joe Aug 11 '16 at 1:26

For everyone here saying a chainsaw isn't effective, they thought it wouldn't be for that episode of mythbusters either. And yet, it was far, far, far more effective than an axe, and actually takes less time to wield.

57 zombies killed for semiautomatic pistol, 67 for the axe and…wait for it… 190 for the chainsaw. Savage, with the chainsaw, was able to “kill” all 190 of the attacking zombies in just 4 minutes.

Is heavy? Yes. Train for it.

don't wear armor so that you're faster than anyone who is, and then aim for any exposed flesh, like the face or neck. Really depends on how much armor and if they are wearing chain mail. Chain is the most difficult problem you'll face. But not everyone had chain that covered EVERYTHING.

Would it need to be adjusted for armor? Absolutely. I suggest industrial diamond tipped teeth.

Would another blade stop it? Pretty likely, but you can build guards for that.

You want chainsaws, baby, you got 'em, even if most people find them laughable. They might breakdown, but for fear and awe in the first few minutes of battle, nothing beats the chain saw.

Now, there are chainsaws that snag less and you don't have to worry about positioning as much--that's what you want to start with, and then make your mods. These chainsaws cost a mint. The standard ones of late often have safety features built in, FYI, so as to not cut flesh much.

EDIT: Wanted to add something about armor. This really depends on WHEN in Medieval times you want to do this and WHERE. Early armies were peasant conscripts of a lord with very little training. Chain mail and a full suit of armor is expensive, and depending on where and when, not as common as you might think. Leather armor was far more common. It's the fully trained knights on horseback you'd have to watch out for. Hopefully the horses are armored. I like horses.

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    $\begingroup$ This is an amusing contribution, but their testing didn't account for an enemy that defends itself. That changes everything. $\endgroup$ – user16107 Aug 11 '16 at 8:48
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    $\begingroup$ Of course it does, however, dismissing the chainsaw as completely useless in combat is not the place to start when answering a question on how to do it. It's not impossible, just unlikely. Some of the objections here (that it's too heavy and hard to wield) are countered by the sheer numbers and how easy it was compared to a traditionally swung weapon, like an axe. The numbers advantage is so large, that even if someone was being attacked with a bladed weapon, such as an axe, the kill rate is higher. All you have to do is train. $\endgroup$ – Erin Thursby Aug 11 '16 at 15:19
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    $\begingroup$ @ErinThursby I wonder how would MythBusters test flamethrower... $\endgroup$ – Crowley Aug 11 '16 at 18:56
  • $\begingroup$ @Crowley they built a military grade flame thrower in another episode $\endgroup$ – Areeb Aug 11 '16 at 22:00
  • $\begingroup$ @Areeb but they didn't test it for zombie apocalypse, did they? $\endgroup$ – Crowley Aug 12 '16 at 0:15

The best melee weapons were always

Spears>swords>maces, and there were reasons for that.

Spears have an incredible range, they were the safest weapons in a battle. Other than being incredibly easy to use and being one of the few weapons at the age that could penetrate armors for a fast kill.

Swords had little to impact, even broad swords, and didn't have much slashing efficiency... not even the most romanticized swords like katanas had the power and cutting efficiency you see in movies, plus they were incredibly hard to use and master. Every Hollywood actor is just a kid agitating a stick compared to the least trained swordsman.

What made them one of the most effective weapons was their manoeuvrability, a warrior could do anything with a sword due to their incredibly light weight, plus any single part of the sword could be a weapon. Usually a good sword man could perfectly keep an incredible pressure on the enemy without ever putting down his guard, even with a single sword and no shield.

Maces are the third best for simply being smaller but heavier swords with an actual capacity to destroy armors and easily stun the enemy. Even with the best armors that couldn't be penetrated by virtually anything the hit of a mace in the chest would not break the armor but directly destroy internal organs and bones. What makes it even better is a mace could break any blade or spear with a good hit or even someone dumb enough to directly hit a mace with a sword using great force will destroy his own sword and some fingers. But being heavier made the mace inferior to swords, even the most mighty warrior would damage and eventually break his tendons for stopping a mace swing in mid air to change manoeuvre while a sword user could do it faster and with no side damages.

A chainsaw has none of these utilities and every possible side effect, is heavier than the mediocre giant zweihander swords, heavier than maces and axes. They give no manoeuvrability, it can only do a few predicable offensive actions and can't defend, while most weapons could both parry a hit and 0,05 seconds after counter attack from any direction. Other than that the other medieval weapons could disarm a chainsaw carrier in literally just the blink of an eye.

Then there's also the fact that with a chainsaw one has little to no mobility, soldiers, warriors, gladiators and duelists all use 100% of their body to fight not only the weapon.

In a technical way even throwing stones would be more effective than fighting with a chainsaw...

Just try to imagine a soldier running around with a chainsaw, rolling, dodging, and blocking hits... well, no you can't cause not even giant axes and hammers which were way lighter than a chainsaw could not offer many of these possibilities. That's why usually those carrying giant and heavy weapons were defended by 10 or more soldiers and even then the giant axe/hammer carrier could only hit distracted enemies or damage it's own allies, and they usually didn't survive much either.

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    $\begingroup$ Spears>swords>maces - That statement is 100% incorrect, swordsmen will overcome spearmen 9 out of 10 times. Mace usage (and axe) was more effective based on the armor the opponent was wearing, not the weapon they wielded. Little disappointed in how many upvotes this received. $\endgroup$ – Twelfth Aug 10 '16 at 19:52
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    $\begingroup$ A spearman has either to be surrounded or be retarded to let a swordman get close enough to strike. $\endgroup$ – άλεξ μιζέρια Aug 10 '16 at 21:16
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    $\begingroup$ A swordsman gotta be retarded to not know how to infight. Spears work well in large formations, nothing else $\endgroup$ – Twelfth Aug 10 '16 at 21:18
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    $\begingroup$ @άλεξμιζέρια I would be very leery of ever saying some thing is always better. Spears have their uses as do swords and maces and axes. The soldiers and generals of the past were not complete fools if any weapon was better than all others then it would be the only weapon used. Think about the gun it is better than all of these weapons for most cases and now all infantry use guns, it universal. But spears were never a universal weapon so they weren't that dominant. There are classic battles where short swords men (roman legionaries) utterly defeated spear and pike men (Greek hoplites) $\endgroup$ – sdrawkcabdear Aug 11 '16 at 0:29
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    $\begingroup$ @Twelfth from experience I can tell you the spear wins the sword almost every time, even in 1 to 1 duel. $\endgroup$ – Davidmh Aug 11 '16 at 8:33

You may be aware of the Warhammer 40K weapon, the Chainsword. enter image description here

It isn't medieval, but might suggest the sort of changes which you could make to a chainsaw to turn it into an effective melee weapon.

  • $\begingroup$ nice. add a pointy end to that, like a bayonet (or even better, a surprise telescopic one), a serious dose of good engineering ... and you might have a potentially effective weapon. $\endgroup$ – Hoki Aug 13 '16 at 11:40

Chainsaw would stuck in mail and can't cut through armor plate. The problem of the chainsaw are :

  • It's heavy. You are less mobile, the strike will be very slow.
  • It take time to cut. It's not lightsaber like effective you have to push through the target.

It would be very effective against a shield and unarmored enemies but in the time the chainsaw go through the shield, you are open to any attack and the guy who see his shield cut to his arm will not stand waiting you remove his arm. He will strike you in your exposed armpit and ... you're dead.

However chainsaw would be a game changer as a siege weapon. No need for a giant tree and 20 people to operate a battering ram. Just a guy with a chainsaw can cut a hole in a very thick door.

If you make it a magic weapon you can say that it is light as a sword and it cut through steel then you have a good weapon. But the way it exist in our world it cannot be used in close combat.

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    $\begingroup$ I'm not sure a chainsaw would be very useful at cutting through doors - you can't really cut with the tip, and there's no other way to cut through a plane. You'd kill yourself before you scratched the door. Not to mention that those gates were often reinforced with metal (and that would become all the more common if you could cut through wood easily), again destroying the saw and injuring the wielder. A much better use would be at cutting down trees to build siege equipment, really :P Chainsaws are extremely specialized tools - they're great for cutting logs, but that's pretty much it. $\endgroup$ – Luaan Aug 12 '16 at 8:53

Don’t use it as a person-to-person melee weapon.

Use it as a tool behind the lines, or by a saboteur. Want to get rid of that pesky trebuchet? A few cuts through some critical (wooden) members will put it out of commission.

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    $\begingroup$ That gives some great opportunities - cut off the army from supplies by cutting a bridge, cut trees accross roads and ravines... you wouldn't want to get close to the army, though - chainsaws aren't really stealth weapons... $\endgroup$ – Luaan Aug 12 '16 at 8:57

If there are only a few chainsaws then they would probably be more effective as a weapon of fear than an actual battlefield device. The sound, smell, and visceral impact of such a tool would impress quite a few folks.

If they are very common tools, a weaponized chainsaw makes little sense outside of usual chainsaw uses (like cutting into wooden walls, doors, or siege engines). The spinning blade of a chainsaw is relatively fragile and if it breaks the chainsaw is useless. So you are unlikely to get more than a few swings in battle before your big clunky weapon is damaged. Many shields are rimmed with metal (or would at least be spiked with nails) which would defeat a chainsaw if they were a common weapon in battle. Chainsaws are not great for thrusting. Most importantly, they are VERY hard to control, so a line of guys with chainsaws are very likely to loose control and hit their own guys (or themselves).

This type of weapon is unlikely to see use outside of elite honor guards designed to LOOK fierce but not be all that effective in battle. Maybe gladiatorial type combat?

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    $\begingroup$ Yes, at a gladiator arena, they might be popular. $\endgroup$ – Guran Aug 10 '16 at 14:23
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    $\begingroup$ Or for executions... $\endgroup$ – vsz Aug 10 '16 at 18:33

There are many aspects of every aspect of human existence, war and combat not being the exception.

If you want chainsaw be a weapon for a duelling, the way most of the movies depict medieval battles, you need to make it not to be chainsaw. Replace the unwieldy engine with the magic\nanomachine one, that fits under the chain, where only guide bar usually located. Voila, you have chainsword, now you need a powerarmor, strong user or a peculiar combat style to ensure that most of the chain movement energy is spent on tearing the enemy flesh, and not onto propelling the weapon in the direction opposite to the chain movement. Replace the lumbering chain with parts from slaughterhouse equipment and you obtain a perfect weapon for peasantry oppression. That said I've never heard about cutting metal with any equivalent of a chain.

However, combat is not always like in Lord of the Rings, people also tend to need to kill things in conditions of limited manoeuvrability. In organized battles as opposed to random skirmishes infantry fights for example used to be a mishmash of desperate stabbing of two tightly packed conglomerations of humans. That is: a murderous blob of humans protecting itself with shield wall at front while wildly flailing spears and halberds tries to create a breach in the shields of opponent blob. When a breach is found, the attacking blob can inject its angry front-liners into the enemy wreaking havoc to its structure, killing and maiming its constituents unprepared to meet enemy at this side of the shields.

This is literally 'shoulder to shoulder' to allies and 'face to face' with enemies, in such conditions swinging a longsword is highly problematic hence a variety of weapons with smaller swing has appeared. Making a strong blow in such situation is difficult, much less pushing the weapon between the shields and swinging it to hit someone. Thus a weapon, that 'swings on its own', would be a treassure here. You just need to push the chain in the opening and shift it slightly till it catches onto comething and watch out for blood spray. Or just push it against enemy shield and rely on those beside you to keep you shielded till foe's arm comes off.

Thus, assuming all possible technical tweaks like putting teeth on every link instead of normal way, reinforcing the bar, adjusting the housing to not to jam on minor flesh patches, the chainsaw might make the weapon, the wrumming of which would whiten the face of hardened warband soldiers. Or warm the heart of the dwarf fending off the insurrection of tentacled demons from deepest tunnels.

That being said, I believe circular saw, if available, would supplant the chainsaw from the manslaughter niche. And if mechanisms of bloodshed are considered and only limitation on gunpowder is imposed, I believe, a civilization with access to combustion or electric engines, needed for the above discussed tools, would quickly abolish the weaponized tools in favour of Da'Vinci's mechanised mowers.


I have no experience of such things, but I imagine a chainsaw makes quite a mess of someone, and the completely alien noise a Chainsaw makes (in the eyes of the medieval militiaman) would make it a very effective psychological weapon.

I completely agree with all of @Nex Terren's points, with all that we know, a chainsaw is an extremely impractical weapon. But if you play to it's strengths and use it for showboating and demoralising the enemy, which history has taught us is often more important then experience or equipment, it could be a very effective weapon of war. Just not an effective personal armament, swap to a sword and shield before you charge a band of pikemen!

  • $\begingroup$ +1 for psychological value, I was thinking the same thing. Kind of like Polish Hussars - cavalry with feathered "wings" whose only purpose beyond decoration was the loud noise they made - as though many more were galloping. Tended to send enemies running. A loud monster eating away at your kite shield would have also been rather disconcerting. $\endgroup$ – kaay Aug 12 '16 at 8:43

Actually there was an accident involving chainsaw and massacre attempt. It failed miserably: chainsaw jammed after second hit.

In case of battlefield it would be even less effective due to armor and so on.

Sorry for necro post, just wanted to add real example.

Here is news link, it is in russian language


As someone who's worked as a lumberjack, I'm quite surprised at the answers here: I think everyone is imagining one-on-one duels between people dressed in plate armor, for which, admittedly, they might be poor because of their weight, one-handed balance, inability to parry well and inability to slice through metal.

But given to your front line, against a force who lacked them, it would be devastating.

Chainsaws are deadly. They are the most deadly tool you can use without a license.

They wound about thirty thousand people a year in the US alone. The wounds take an average of a hundred and ten stitches. That's when not trying to cut people up with it. About two hundred and fifty people a year die from them.

Consider two spear-and-pole-wielding lines meeting, but one is equipped with spears, the other pole-saws.

The spears get mostly deflected by the shields. The pole-saws slice right through all the leather armor and felt padding and wooden shields and other nonsense. They meet a surface they can't penetrate, the pole saws actively grab onto it, pull it to one side, and crawl around it.

Yes, you'd need a secondary weapon. But the majority of the foe's front line now needs an average of 110 stitches. You've struck terror into their hearts and nobody wants to step up to the meatgrinding machine that is your front line.

Chainsaws are an excellent tool, then, for massacres of lightly armored foes by a heavily organized force.

But they come with a downside: they are the most deadly tool you can use without a license, because they mostly maim the user. The whole "moving of their own accord to find they way past any impenetrable armor" thing can work against you, too: they kick back, they leap up into your face and neck, or down into your own leg. Pole saws are safer, but only to an extent.

Perhaps the most effective way to use them, then, would be using a formation like the Roman turtle, but with either pole saws, or a flap in the shield to push a chainsaw through, clamped in place such that the chainsaw cannot buck and twist in the hands of the wielder enough to slice himself or his comrades, and the wielder can use both hands to steady it and the shield together.

Combat is an arms race, though. Just as loggers now wear fibrous trousers to prevent injury from chainsaws, so people would start to wear heavy fibrous clothing to tangle the saws, and they would also clad their shields in it.

But arms races only have so much speed. The initial introduction of them could be enough to win a war.

[Edit: From pluckedKiwi's comments, I realize that polesaws are not known to everyone. A polesaw is a chainsaw with a pole between the engine and the blade, rather than placing a regular chainsaw on the end of a stick. This gives you balance: the weight of the engine and fuel tank (or motor and battery) near and behind your hand, counterbalances the length of the shaft and the weight of the blade at the end, arguably balancing better than a spear. However, it's still a decently heavy piece of kit.

I still think regular chainsaws mounted behind shields in turtle formation would be the best plan to use them. However, the lack of range compared to any missile weapon of the same size and weight does make them kinda silly.

Combat modifications to the blade (larger teeth; separating each tooth by two or three empty links as is used when cutting stone; faster chain replacement with a sprung blade instead of bolt tightening) would certainly help. As would ablative armor for the wielders to protect them from kickback.

If the question were "what modern stuff other than guns could make a medieval army really fricken deadly" I might not even bother mentioning chainsaws. Better armor would get my first vote. But given the question, yes, chainsaws would give your front line a crushing advantage. Rather than just being a consumable, disposable mass of bodies to absorb (or make) a waved attack, they'd be a death machine, grinding through flesh with a speed the opponents had never imagined. Sure, any missile weapon beats them. One gatling gun could best your entire army of chainsaw wielders. So would a line of bowmen with longbows.

But in medieval days, the tank of the day was the armored horse. A charge of trained horse-riding knights who've been trained their whole life, against a chainsaw turtle with a month's training... despite the very significant problems of armor penetration, particularly as the science of making plate armor got better, my money's on the turtle.]

  • $\begingroup$ Have you any experience actually using a chainsaw? I cannot imagine the extent of just how unwieldy a chainsaw on the end of a long pole would be. I will take the spear over a chainsaw on a pole - the former is quick and will find the gaps in your guard, the latter is excessively cumbersome and easily deflected (it has no magical 'grip' power to stick to anything it touches - quite the opposite). Opponents will not just stand there like a tree - they move and attack you while you are trying to attack them. $\endgroup$ – pluckedkiwi Aug 12 '16 at 16:28
  • $\begingroup$ @pluckedkiwi: Yes: I worked as a lumberjack in the UK. Have you used a pole saw, or are you just envisioning a regular chainsaw on the end of a stick? $\endgroup$ – Dewi Morgan Aug 12 '16 at 17:11
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    $\begingroup$ I was envisioning a pole saw (edit: though a much longer pole than any I've used), but now I'm picturing a regular chainsaw on a stick, which is hilarious. Still a lot more weight out at the end of a pole than a spear point or even a halberd. Speed of attack and a quick recovery time are vital in combat. You are trying to fight another dynamic human who actually cares to live just as much as you do, not a tree which sits immobile providing something to push against. $\endgroup$ – pluckedkiwi Aug 12 '16 at 17:18
  • $\begingroup$ Makes you wonder why there are so many madman knife attack and so few chainsaw attack $\endgroup$ – Madlozoz Aug 13 '16 at 4:36
  • $\begingroup$ Knives are cheap, plentiful, quiet, quick to whip out, easy to hide or dispose of. They do only a tiny fraction of the damage but you can shiv someone and move on. But the question doesn't ask "what's the best weapon for a random modern-day crazy person killing". It doesn't even ask what'd be the best weapon to take back to medieval times. It just asks if chainsaws would be effective in combat back then. $\endgroup$ – Dewi Morgan Aug 13 '16 at 19:09

Chainsaws when against flesh don't really cut that well, they rip flesh / almost skinning the flesh they come in contact with. But you are trying to kill someone so that doesn't matter too much.

But one modern protection that you see is a actually a heavy cloth-like material that frays when the teeth of the chainsaw are in contact with it, that fabric then jams the chain stopping it. Then you have to untangle the mess to continue, assuming you didn't actually injure yourself.

So defenders could cover themselves in regular metal armor or heavy cloth on top of leather. The first use of the chainsaw on this armor and the chainsaw is immediately useless and leaves the user open for counter attack.


As explained in the other answers, an actual chainsaw is a bad weapon but you allowed for modifications so how could we build a chainsaw-like weapon with current/near future tech?

Step one: change the "teeth" : We need to optimise the form of the teeth to cut through steel while reducing the amount of ripping. something like a half-circle blade, made of extra-hard steel should work.

Step two: replace the chain and engine. : The engine/chain design is the major point of failure of a chainsaw, so let's replace it with a railgun! on each side of the tooth there will be a double rail where you pump electricity through, accelerating the actual blades. if a blade get stuck you get very little mechanical force acting at the "swordblade". Instead the railgun will start to overheat...simply add a thermal sensor that shuts down the power-source. If we limit the speed to about 500m/s we should have little problems with wear&tear on the rails (the primary problem with current railguns) while still each bladecut will have the force of a pistolshot.

Now all we need is a power-source to keep this thing running for a hour or so and a person strong enough to use it...

  • $\begingroup$ Half-moon teeth improve some issues, but cause others. How do you actually convey force into cutting/tearing the material instead of just pushing the chainsaw and the armor apart? Chainsaw hits armor - bounces away. The teeth just slide along metal - might be good against cloth though (would reduce the problem of fibers getting pulled back into the mechanism). $\endgroup$ – pluckedkiwi Aug 12 '16 at 17:10

The problem is that it really won't cut into something without standing still and proper placement. You know this if you've tried to cut straight through a limb and the tree starts binding on it.

What would happen is that you swing the blade down on a sword, shield, or armor, it doesn't slice through like a light saber, and the chain's motion causes it to bounce back towards you. Seeing this, your opponent then starts pushing you with their weapon, trying to throw you off balance so that you inadvertently bring the spinning chain down on yourself.

To improve upon it, you would need some sort of plasma-field chain so that it just cuts through anything.


A normal modern chainsaw would be a pretty ineffective weapon. But I think that a specialized combat chainsaw could be useful for special situations in medieval warfare. The best use I can think of is for heavy cavalry specifically designed for attacking skirmishers (light infantry).

I'm imagining two chainsaws joined with hinges where their handle would normally be. A rugged support structure mounts this in place of a yoke, with backstops preventing the hinge from getting too close to the horse. The chainsaws would be pointed downward when on the stops, and if lifted slightly they would be parallel to the ground (blade edges pointing backward and forward, not up and down). Probably it would use a kind of ratchet system so the rider wouldn't need to actually hold them in place. The chainsaws would need to be heavily modified for length and durability, because even peasant levies are going to have some metal objects which would cause you trouble.

So basically it would be a chariot of death, routing poorly-armed and armored peasants. It would need to be pulled back before spearmen or knights were in range. But if you have access to gasoline, I think that gelling it and using it for flamethrowers would be far more effective.


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