I am developing a world were modern firearms are introduced into a medieval setting (I realize that this has been done since Mark Twain's A Connecticut Yankee in King Arthur's Court). I'm working on how my world will react to the introduction of such weapons.


  • 14th Century Europe (if a specific location is required, use France).
  • A knight wearing common plate mail of the time.
  • An M1911 pistol using a .45 ACP round.


What 14th century technology could be used to protect the knight from the M1911 pistol while leaving the knight able to walk, fight, and ride a horse?

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    $\begingroup$ Magnum .357 vs commercial grade heavy steel door $\endgroup$ Oct 18 '20 at 17:41
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    $\begingroup$ Please note that the "plate mail" naming is inaccurate and not historical. Mail (or more correctly maille) just meant the chain armor. So there was no such thing as chainmail (it would have meant chainchain), or "plate mail", just stick with "plate armor". $\endgroup$
    – vsz
    Oct 19 '20 at 4:31
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    $\begingroup$ Are we to assume that the time traveller with a 20th century gun has an unlimited supply of ammo, spare parts, lube and all that they need to maintain their gun. Or guns, if we are talking about a platoon instead of a single soldier. $\endgroup$ Oct 19 '20 at 7:03
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    $\begingroup$ The logistics matter here: introducing the pistol (and its manufacturing chain) is one, thing, but accurate rifled cannon completely change the dynamics of the battlefield! $\endgroup$
    – pjc50
    Oct 19 '20 at 9:35
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    $\begingroup$ Steel breastplates were used as late as WWII and, with luck, had some effect on contemporary SMGs. Since .45 ACP is about the least armor-piercing round you can possibly get, short of hollow point rounds and shotgun shots, the knight's chances would be pretty solid given some preparation. $\endgroup$ Oct 19 '20 at 12:56

12 Answers 12

  1. Medieval armor was intended to offer almost full protection against bladed weapons, partial protection against lances, arrows and cross bow bolts, and a little bit of protection against blunt force weapons. It didn't do any good against heavy projectiles, against cannon or against direct hits by arquebus balls.

    Most types of modern body armor, such as those used by police, offer protection against light bullets travelling at great speed, but are useless against bladed weapons. Some types of modern body armor, mostly used by the military, offer a certain degree of protection against bladed weapons, but far less than medieval armor.

  2. Medieval armor would be essentialy useless against a modern high-power pistol bullet. Some kinds of multilayered textile / leather medieval body armor would offer a certain degree of protection against small caliber anemic pistol bullets.

  3. Medieval technology does not have to do anything against pistol bullets, because pistols are useless in battle.

    • Consider a serious medieval force, such as Prince Edward's at Poitiers fighting against and a force armed with modern pistols. Pistols are only useful at close range, say 25 meters of less; Prince Edward's longbowmen would have no trouble engaging the opposing force from way out of pistol range. (In the real battle they engaged the French infantry at a distance of more than 200 meters.)

    • A cavalry charge at full gallop covers about 350 to 400 meters per minute. Let's say that the opposing force featuring pistols can miraculously fire accurately at 50 meters: the charging horsemen will cross that range in 7 to 9 seconds. There is a reason that defending against heavy cavalry charges went from pikes directly to cannon and then machine guns; small arms just won't do.

  4. Consider that the ratio between bullets fired in WW2 and enemies killed is somewhere between 5,000 and 50,000 to 1. And that was with rifles, not pistols, and soldiers did not wear any kind of body armor.

The conclusion is that nobody would bother developing some sort of superarmor capable of "protecting the knight from the M1911 pistol while leaving the knight able to walk, fight, and ride a horse", because no such technology is needed. Indeed, in real history nobody bothered developing any kind of such technology for military use until very very recently. They might make some experiments, which will fail, but they would not spend large amounts of sweat and treasure seeking an elusive protection against such a small threat.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Oct 20 '20 at 11:24
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    $\begingroup$ I understand this is a frame challenge but I think it ignores the question "what if" - if a serious force of several hundred guerilla fighters did infiltrate a city and began attacking with modern pistols, someone would surely try to create an armour to protect themselves.You make so many assumptions about the tactics of warfare that will be employed in this story that have no basis in the question. So while I understand it's a frame challenge, I think it's a rather poor one. Science based doesn't prevent alternative history and no one said anything about using the pistols in a large battle. $\endgroup$
    – TCooper
    Oct 20 '20 at 23:40
  • $\begingroup$ Modern armor still uses hard plates either from ceramics, metals or fiberglass.... Wearing soft armor alone might not let a bullet penetrate you but the impact will explode your bones anyway... So pretty much any real modern armor also protects from cuts $\endgroup$
    – user81643
    Jan 7 at 9:57

Back when firearms were introduced on the battlefield, armorers started to produce musket-proofed armor. This caused a little arms race, which the musket ultimately won, but better armor helped at first.

  • This article has some penetration figures, with modern pistols and rifles for comparison. A modern pistol, with the smaller and lighter bullet, is comparable in penetration to a musket with somewhat higher energy.
  • Note that .45 ACP might not be the best choice. 9×19mm has nearly the same energy and a smaller cross-section. A 5.7mm pistol might be even better, but harder to get.
  • For that matter, look at a shotgun with slugs or a hunting rifle.

Most likely, yes

.45 acp is a fairly low velocity round that doesn't need a huge amount of steel to stop it. Assuming hardened steel is being used for the armor. The breastplate is the toughest part of the armor and has a chance to deflect the round as well.

Plus, once the threat is realized, they can just make thicker breastplates and be pretty certain a .45 acp won't penetrate. (Or carry a metal shield in addition to the armor)

But don't just take my word for it, here's a video of someone shooting a reproduction helmet with a variety of guns, including .45acp, which does not go through. So stopping that particular round is, at the very least possible, but not guaranteed. That seems to be close to the upper limit for what it can take though.


Rifles though, are pretty much guaranteed to penetrate, probably even through a shield as well.

  • $\begingroup$ Regarding helmets in particular, preventing the round from penetrating doesn't necessarily mean the wearer has been protected, as the armour may still deform, as we see in that video. $\endgroup$ Oct 20 '20 at 9:25
  • $\begingroup$ @Max Barraclough, Yes, I would agree with that. The helmet wearer may have been in real trouble, although a padded arming cap may have helped. A breastplate would probably have more room to safely deform though. $\endgroup$
    – Redbud201
    Oct 21 '20 at 23:44

Method 1: Presuming you have a 7 round Colt, the technology you need is 8 fellow knights on horseback armed with just about anything heavy. If these charge at the gunman, whilst it's theoretically possible that he/she could shoot sufficiently accurately and quickly to kill 7 of them from the point they get in range, I would doubt it is possible to reload to kill the final knight who can hit the (presumably unarmed) gunman with a handy sword. The knight you seek to protect can observe proceedings from a safe distance. If you have an 8 round Colt, add one more knight.

Method 2. Put your knight in a castle. Pull up the drawbridge. Defend the castle with the normal 14th century accoutrements (e.g. boiling oil, archers). Sure it's possible one or two shots get through the castle's enormous wooden door but provided your knight doesn't stand near it, they are not going to get hurt. Your knight remains free to walk, fight, and ride a horse (inside the castle). Once the gunman has run out of ammunition, the knight can chase him down outside.

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    $\begingroup$ +1 for the tongue-in-cheek method 1 ! ^^ As for method 2, please be reminded that oil was MUCH too expensive to dump it on assailants, while boiling water or even sand were much cheaper and as/more efficient (especially sand, which keeps burning when it got under gambison/armor). I can’t remember reading about dumping (see what I did here ?) boiling excrement though. $\endgroup$
    – breversa
    Oct 19 '20 at 10:04
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    $\begingroup$ #1 isn't really tongue-in-cheek. This approach was basically what we used in WWI: if you throw enough guys over the top, even against machine guns some will make it. $\endgroup$
    – Dan W
    Oct 19 '20 at 16:01
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    $\begingroup$ @DanW indeed. I could have simplified Method 1 by using 8 serfs armed with clubs. A lower likely survival rate, but maybe it's easier to "recruit" serfs than knights. $\endgroup$
    – abligh
    Oct 19 '20 at 16:57
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    $\begingroup$ @Perkins : Actually, according to Wikipedia (en.wikipedia.org/wiki/Early_thermal_weapons#Hot_oil), oil was actually heated colder than water. But at any rate, oil was a much, much rarer defense weapon that thought to be. To quote the above Wikipedia link : "Hot oil was considerably less common than boiling water or heated sand, which were cheap and extremely effective; even "dust from the street" could be used." $\endgroup$
    – breversa
    Oct 20 '20 at 7:40
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    $\begingroup$ @breversa It was "heated, not boiled" due to its smoke point being lower than its boiling point. So the stereotype of "boiling oil" likely only happened by accident (and with good reason, oil smoke can be explosive). Don't mistake that for the oil being cooler than water though. The smoke point of common oils ranges from about 200C to 400C, so between twice and four times as hot as boiling water. Hence Josephus' description of how it "fed upon their flesh like flame itself". Boiling water won't do that. (Though live steam can if hot enough.) $\endgroup$
    – Perkins
    Oct 20 '20 at 17:25

Jousting armor

It protected it's wearer from the lanсe with total wight/energy of enemy, his armor, his horse combined. Total energy on the tip if the lance is at the order of sniper or antimaterial bullet - far greater than for pistol one.

And this protection was quite reliable - deths were not that common on medieval joustings. Most clashes brought no harm for jousters.

In XIV century jousting was quite a developed sport - so it was not hard to find gear, if you have money.

I think we all know downsides of such protection: limited visibility, mobility (but still can walk and fight on foot), and astronomical price.

But still - if some knight would like to punish some heretic with devil weapon - he have the way to protect himself from the projectiles of hell!

  • $\begingroup$ very good answer. The amount of force via the tip of a lance seems to be an enormous amount more than any pistol's bullet. $\endgroup$ Oct 20 '20 at 3:03
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    $\begingroup$ @meaninglessname, not that enormous. Total energy is about 10-12 kJ (sniper rifle has about 3-5 kJ). But unlike bullet, lance does not deliver all the power and impulse to target. The Third Newton's Law is a harsh mistress. Anti-tank rifles with same power as lance can easely brake sooter's shoulder. To soften things up for attaking knight lance shatters on strike. So total energy delivered by lance is times smaller - about 1-5 kJ (greatly depends on knight's skills, horse and gear). $\endgroup$
    – ksbes
    Oct 21 '20 at 5:38
  • $\begingroup$ Ah. I had only done some very basic research. Still a good answer though. $\endgroup$ Oct 23 '20 at 2:58

Depending on ammunition, you M1911 is not much different to a crossbow except that it does not hit as hard, or penetrate as well, and has shorter range. Better rate of fire, of course.

Consider a mounted knight with a shield and lance charging at a man on foot with a .45. Which would you rather be?

A cool-headed man with a .45 and good aim might win, especially if he was unsporting enough to shoot the horse. But I would not rate his chances that highly.

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    $\begingroup$ An M1911 will penetrate much better than a crossbow. All modern firearms will. They will go clean through both sides of a car and still have enough energy left over to kill someone on the far side. $\endgroup$
    – Ryan_L
    Oct 18 '20 at 22:36
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    $\begingroup$ Gonna need a [citation needed] on the claim that a .45 "does not hit as hard, penetrate as well, and has shorter range". Sure the 1911 only has an advertised effective range of 50 meters, but, energy-wise, the bullet blows the bolt out of the water. A typical crossbow would be packing maybe 100 joules while depending on the cartridge, the .45 easily reaches 500j with some loads edging closer to 800j. The bullets would probably go through shield, armor, and knight without major difficulty. $\endgroup$
    – Dragongeek
    Oct 18 '20 at 22:52
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    $\begingroup$ Note that the range is listed as for the pistol, not the bullet. While it's true a longer barrel increases gun effective range (assuming the ammunition has been loaded to match), it's the other elements that are going to primarily limit the range for a pistol: short-range sights, no stock, how the pistol is handled. $\endgroup$ Oct 19 '20 at 6:00
  • $\begingroup$ @Dragongeek: The high energies are a direct result of the high velocity, which is made possible by the low bullet weight. This helps to keep the recoil down, because recoil and inpulse scales linearly with velocity while energy scales quadratically. But this high velocity does cause high aerodynamic drag, which explains the short range compared to a crossbow bolt. $\endgroup$
    – MSalters
    Oct 19 '20 at 10:31
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    $\begingroup$ Ryan_L - it depends very much on ammunition. Normal hollowpoint ammunition would not penetrate any further than the shield $\endgroup$ Oct 19 '20 at 17:24

It would be a hard undertaking in the 14th century. Firearms were just introduced in Europe, and neither gunsmiths or armor makers had yet a lot of time to improve their work. As such a "bullet proof" armor did not yet exists.

After the introduction of firearms in Europe, there was an arms race between gunsmiths, making ever more deadly guns, and armorers, making ever more bullet resistant armor. There is historical evidence, for knights on horseback using wheel lock pistols, but you had to shoot an armored knight point blank to stand a chance at beating a 15th century armor.

Your best bet to beat a bullet is a layered defense; a cone shaped, hardened steel plate, over the regular steel breastplate. First layer makes the bullet tumble, second layer stops it. Something like that was used in WW1 to stop rifle bullets, so it should stop 45 ACP as well.

45 ACP has not that much penetrative power, so a regular plate armor, or even chainmail, might stop it, depending on range.

They had the technology to produce hardened steel in the 14th century, but the art of armor making had yet to reach it's peak. So I imagine, the best armor makers of the time could come up with a suit of armor, that could beat a 1911, but it would be quite the feat.

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    $\begingroup$ @vsz "chainmail" isn't a historical term, but it is a commonly understood modern term for maille $\endgroup$
    – Kevin
    Oct 19 '20 at 18:04
  • $\begingroup$ @vsz also you're polluting the comments by posting the same response everywhere $\endgroup$
    – bendl
    Oct 20 '20 at 14:21

Silk has been shown to be a low-tech armoring material.


It looks like it would depend on the particular plate armor.

The tricky stat to find is how thick of steel you need to stop a bullet. The kind of people who are interested in stopping bullets are the kind of people who are willing to make it just a bit thicker. You know, just in case. I found lots of people who would vouch for stopping a 9mm or .45 with 1/4" steel plates, especially if you have it at an angle.

However, for a lower bound, I did find one anecdotal argument:

I am a restaurant repair tech, and I happened to be on site for a shooting. .45 ACP FMJ did not penetrate 16 gauge stainless at 8'. It did however make quite a mess of the syrup lines that were hit.

16 gauge is 1.518mm thick.

The thickness of plate armor varied by quality, by there's evidence for plate between 0.75mm and 2.5mm thick, with 1.5mm being common.

So I'd say its reasonable that the armor could protect you from a .45 as-is. Of course, there is the question of steel quality. If the anecdotal evidence is to be believed, there's a question as to whether medieval steel could stand its own against restaurant supply stainless steel.


<pedantic alert, but may impact your considerations of how you build your world>

In our world, plate armor was anything but "common". It survives well and so it appears that everyone wore this, but the modern vision of fully-articulated armor of nearly all-metal construction was very rare and only affordable to the ultra-rich who could spend that much on something dedicated only for either parades or warfare, and custom forged for themselves exclusively. It took months to construct these suits so that they would allow enough mobility to be useful, and that utility varied widely. Again, this was quite expensive.

You didn't want to fall into a pond or a deep patch of mud wearing this stuff, either. See https://en.wikipedia.org/wiki/Frederick_I,_Holy_Roman_Emperor, and the many French knights who fell from their horses at Agincourt and drowned face-down in the mud. Some suits of heavy armor were specifically designed to be worn only on horseback and were so heavy that the knights needed cranes to hoist them up onto their horses. These, along with the horses, were the battle tanks of the time.

In reality, most metallic armor was constructed of bands or scales sewn onto padded cloth or leather, or chain mail suits with a few strategically placed plates that offered little protection against blunt force. The punch of a .45 round provides plenty of blunt force even without penetrating this kind of armor (which it likely would). Even mail armor was rather expensive. Aside from that, the rest of anything that can be considered armor would have been cured or soft leather and padded cloth.

It is possible to forge hardened plates that would stop, or better yet, deflect this projectile, but the resulting armor would be terribly heavy. What is the metallurgical level of your world? Do they have the skill to harden steel, and how good is the steel they make. Material tech is important here, but plain old mild steel would need to be thick, and therefore heavy. If the steel and hardening techniques are available, one might be able to wear this on their chest and maybe as a helmet, but a full suit of it would be very difficult and clumsy to move around in on a battlefield and would afford a marksman plenty of time to aim for a soft spot, and it would be exhausting to wear for any practical amount of time. Many medieval battles lasted for hours, if not days. The armored knight would be a sitting duck, essentially.

I don't want to write your story for you, but maybe your denizens would figure out that pistols need time to be reloaded, and maybe they could figure out that layers of wood and sheets of steel would make fantastic tower shields to stop initial volleys of bullets that once survived make the shooters the sitting ducks to be butchered a bit later. The Greek phalanx made effective use of this sort of wall o' shields; that's an old trick. Tactics win, armor and weapons are not the only keys to victory. The point is that softer materials and layering might be discovered to be more effective at absorbing the kinetic force of a bullet than single plates of metal. Shields can be dropped, and the warrior behind it then has good mobility to advance and slay a reloading pistolier (but they'd better hurry!).

The English longbow and bodkin points on the arrows essentially invalidated medieval armor and ended the "arms race" between weapons and those types of armors. Once full suits of armor became obsolete, the focus shifted to mobility. There were plenty of breast plates worn right into the 19th century (some armor is still better than none), and generally by cavalry forces, but due to cost considerations, the growing size of armies, and the change in strategy to speed over brute force, combined with the improving quality and effectiveness of firearms, armor virtually vanished until material science caught up in the 20th century and it was possible to construct plastic armors that would stop bullets. When you get hit by a bullet wearing this stuff, it still knocks you on your butt, can break ribs, and so forth. Bullets pack a whallop.



Back the steel plate up with molded ceramics and then silk glued to this. You would also likely need some thicker wool padding to help absorb the blunt force. The armor likely wouldn't be able to take many hits, especially to the same location, but this would easily defeat 45ACP without adding "much" more weight.

Details: Original plate armor steel would likely not be the best that 14th century metallurgy could come up with to as part of the laminate armor system, but should suffice. As with anything, over time, accidents and research would lead to a more deformable steel.

Ceramics are well detailed as being an integral part in many laminar armor systems. Even cheap home improvement bathroom tile can be used, so 14th century ceramics should be a usable alternative with maybe some minor chemical changes.

Silk was used in body armor for quite some time. It is more there to catch any small pieces that may make it through but more to keep the ceramics layer from completely shattering in to powder.

And the padding can be anything and was actually part of many plate armors for the same use as for this, so probably wouldn't be anything new.


Steel armor has been played out here. Ceramic armor could almost certainly have been crafted by 14th century artisans, and would almost certainly be able to stop a bullet. Whether they would think to create it themselves is a matter for your story.

  • $\begingroup$ Any reason for the downvote? $\endgroup$
    – bendl
    Oct 21 '20 at 19:27

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