How can medieval knights protect themselves against modern guns?

Question

How do a you make a knight with armour and a sword formidable against a modern-day soldier with gear and a gun?

And how can you make a medieval army formidable enough to face a modern day army?

Answer 1

This is basic asymmetric warfare. It can work. Ask the Viet Cong how they held off the most powerful superpower in the world...

What you don't do is take on the modern army on their terms, or even the terms a knight would be used to. Avoid an open pitched battle, it would be suicide.

Ditch the armour, take a dagger instead of a sword. Carry out a sneak attack against a small enemy base. Now you have first blood, and some guns and ammo of your own, maybe grenades. Fight on home turf and use local knowledge. Fight in terrain that works for you and against the modern army - dense forest, tunnels. Construct effective booby traps. Be able to mingle seamlessly in with civilians. Conduct psychological warfare - if the enemy's patrols just disappear without trace, they get spooked. If the modern enemy has embedded reporters, wage media warfare - expose the embedded media to horrors, ensure they see the full suffering of their own troops and your most innocent civilians and hope to suppress the appetite for war in the enemy's homeland. Depending on the temperament of your enemy you might consider infiltrating knights into their cities to conduct terror attacks, although this risks hardening their resolve against you.

Note that all of this is stuff that could feasibly be done by knights, but it doesn't look much like the way knights would historically have fought. The aim isn't to defeat your modern foe militarily, it's to demoralise them into giving up and going away exactly as the VC managed.

Answer 2

Historically, knights were protected from firearms. Armour from the late 1400's on was "proofed" by firing a shot from a handheld firearm into it, allowing the purchaser to have a visible sign that the armour was capable of stopping a bullet.

Handgonne from the 1400's

Proofed suit of armour

The issue was that while it was possible to create armour which could stop bullets, it was increasingly heavy and inflexible, and also increasingly expensive to purchase. Essentially the cost was rising far faster than the effectiveness of the protection, and the diminishing returns caused armour to be abandoned until advances in material science created strong, lightweight materials like Kevlar, Spectrashield, titanium strike plates and ceramics capable of absorbing bullet strikes.

It should also be noted that metal armours were used against firearms even in the 19th and 20th century in very limited amounts. The Australian criminal "Ned" Kelly had a home made suit of armour which protected him from bullets (for a while), and various forms of metal armour were tested in the trenches during WWI. However, much like knights discovered in the 1500's, proofed armour capable of stopping bullets was heavy, restrictive and very expensive.

WWI British "Trench Armour"

Soldiers can be protected against modern firearms, but most soldiers are generally protected more against shell fragments and splinters for much the same reason that a medieval knight was not protected against firearms: Level IV armour capable of stopping full power rounds is bulky and expensive. The soldiers may need mobility and flexibility more than full protection.

SoF (Special Operations Forces) operators in Level IV armour

This suggests that a modern "Knight" may be kitted out as a SoF operator in Level IV armour, so able to withstand being shot by firearms (especially pistols, submachineguns/Personal Defense Weapons or assault rifles). However, in order to function effectively with a melee weapon, they would also need to be trained to avoid any area where they are in the open and exposed to shots, and only engage in melee combat at close range, such as ambushes inside confined spaces like buildings. Incidentally, this would actually reduce the effectiveness of actual knightly weapons: the primary arms were pole arms which provided extra reach and leverage for the knight to deliver a crippling or killing blow; swords were sidearms and for use when the user lost or broke a pole arm.

As for entire armies, modern armies have logistics which allow them to span the globe and enablers which enable them to operate and attack across the land, sea, air, space, cyber and cognitive domains, so any medieval army (even one with modern Level IV armour and titanium pole arms and swords) will simply have no chance at all. Being tracked by satellite, bombarded by aircraft or artillery and subjected to PSYOPS (Psychological Operations) attacks such as continual loudspeaker noises preventing sleep or effective communications, while having horses shot out from under them by snipers 2000m away using .50 BMG (50 Caliber Browning Machine Gun) sniper rifles without any possibility of response will eliminate them as a force in being, and that is without having them confront a force with modern AFV's (Armoured Fighting Vehicle), how will knights fight against tanks and attack helicopters? Even IFV's (Infantry Fighting Vehicle) with 25mm cannon and machine guns will cut swaths through them from far beyond any possible response. Modern troops will clear buildings with explosives and flame weapons rather than engage on melee combat.

Knights? You've got to be kidding!

So while it is possible to protect a man with modern materials against firearms, there is no practical way to effectively fight against modern soldiers using medieval weapons, tactics or military organizations.

Answer 3

The power of MAGIC!

http://www.magicandmagicians.com/images/DougHenningtoplarge.jpg

Something funky happened to get these two armies in the same place at the same time. Get more of that. Then magic up your medievals. For example: make them really fast and also hard to see. The cavalry charge will be on top of and through your moderns before they know what is coming. Your knights do what they do best, but better. It will be engaging fiction!

Thinking ahead - 11th century Crusader type knights might take umbrage at regular magic, it being satanic and all. Your magician might need to be of some Christian variety - maybe a barely tolerable Greek Orthodox wizard of some sort.

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I am thinking of the scene where the modern drops his rifle and picks up a sword. Honor would compel the knight to also dispel his magic advantage and they fight one on one with the swords. On besting the soldier, the knight accepts his surrender and brings him back as a captive to be ransomed.

Answer 4

There's three separate questions here (one in the title, two in the post). I will try to answer them in descending order of obviousness.

And how would you make a medieval army formidable enough to face a modern day army.

First of all, "modern day army" is very vague. Are we talking about something like the USA or Russia? Or the national army of a country like Gambia? Or even the Pope's Swiss Guard can be considered an army? Also, it's one thing when you just mean the infantry with their personal weapons and a completely different one if you include tanks, fighter jets, bombers, ICBMs, nuclear weapons... Additionally, is the supply chain needed to maintain the army active? Or is it just the usual, very boring by now case of a bunch of troops transported into lalaland or isekai or whatever that nonsense is called?

Assuming you have a non-trivial amount of personnel, reasonable resources and the bare minimum of armored vehicles, and no shortage of food, ammo etc, the answer is you cannot. A modern army backed by modern technology, science and resources would defeat any non-modern army in Earth's history which would be backed by contemporary to it technology, science and resources, even if it was heavily outnumbered. It is only around WWII when the "non-modern" army will start to stand a chance.

If you are intending to create a situation where the weaker army wins, you have to:

a) Limit the modern army's capability or willingness to achieve a decisive victory instantly, which it would logically possess (ie deprive them of all large-scale weaponry and heavily armored vehicles, no overwhelming numbers, hesitation to kill etc)

b) Cut off the modern army's supply chain (ammo, food)

c) Exhaust its remaining supplies and eliminate personnel through attrition warfare, sabotage, assassination, scorched earth, whatever

Alternatively you can also employ deception and subterfuge. However keep in mind that a modern (professional) army tends to be more disciplined than the rabble of the middle ages. Even if they believe the enemy has surrendered unconditionally, they are likely to still keep some lookouts just in case (especially true if the army is accompanied by its command chain). So the whole "get them drunk and slaughter them in their sleep" may not only not work, but horribly backfire when your would-be assassins are brutally butchered by guards you weren't even aware of (keep in mind camouflage, sniper rifles etc).

Anyway, it's a long shot, but with a lot of deus-ex-machina from the author, as long as the differences in the two armies are not too large, you can sort of make it believable.

How do a you make a knight with armour and a sword formidable against a modern-day soldier with gear and a gun.

You can't. Nearly every situation which would be disadvantageous for a gunman (limited visibility, close quarters combat etc) would be at least equally disadvantageous for a man in heavy armor wielding a heavy sword. Even an ambush would be extremely difficult to pull off for an armored knight. If you take away the sword and armor and have a fast, nimble assassin armed with knives (yes multiple knives), you may have a shot with an ambush, or in extremely close quarters combat in narrow spaces where aiming a gun is difficult but stabbing someone with a short dagger isn't. Even then, if the soldier is also afforded modern armor (kevlar etc) then he has the advantage again.

Other answers apply which follow the same logic as before: cut off the supply chain and force the soldier to starve or exhaust his ammo on your allies. Deception and subterfuge also apply to the same extent as discussed above.

How can medieval knights protects themselves against guns?

Surprisingly, this is the answer that most favors the "medieval" army (depending, of course, on what you classify as "guns"). The answer to "how can I protect myself against X ranged weapon" is "put something between yourself and that weapon that it can't penetrate". If we're talking about handguns and such, a relatively simple thick wall would suffice. Even against machine gun fire, a castle wall would be able to protect the knights. When we start talking about heat-seeking projectiles, bombers, ICBMs... well we're not talking about guns any more, are we?

If the purpose of the knights is only to defend (and possibly outlast) lightly-armored modern infantry, then they need to hole themselves up in a well-stocked castle. Again the supply chain is key: assuming that the soldiers have none, the knights only need to wear them out. Storming a castle gate would not be a simple matter for infantry armed only with anti-personnel rounds. In fact, even if you were to equip them with something like a rocket launcher that could take down the gate, as long as they did not have a tank or other armored vehicle to break through, the regular castle defenses (moat, boiling oil, rocks from above etc) might suffice to keep them out.

Answer 5

You can't, that's why modern armies are using rifles and not swords.

• Send highly trained fighters with daggers and light gear. There is the proverb "you can always take one with you." But those are assassins and not knights. They would not be fighting openly. Fighting that way goes against the ethics of a knight.
• Fall back into dense woods with medieval road nets. Bows and crossbows from ambush, Robin Hood style. Again losses will be apalling as modern troops assault through each ambush.

Answer 6

The power of Si Fi Tech!

Since you didn't specify hard science, the skies are the limit.

Your first question:

"... make a knight with armour and a sword formidable against..."

doesn't have the word "Medieval" in it, so,

https://www.fanatical.com/en/dlc/warhammer-40-000-space-marine-power-sword

Warhammer 40000 has melee super-techy swords and power armour that defy (current day's) known physics. You basically got a man shaped armoured vehicle that smashes things. Something like the armour, at least, might not be so hard to make with near future tech (Iron man, without the flying bit).

Still, the power of ranged weapons today make it practical to at least add ranged abilities to this setup.

Your second question about medieval armies? They might appeal to the tender heart of the modern army's soldiers, who'll let them win out of pity.

Answer 7

I think there are 3 ways that a medieval army could defeat a modern force.

1) Classic Medieval Siege: While a modern force in a fortified city would be formidable problem, it would suffer from same limitations as any army in the same position. Namely limited rations, access to clean water, and susceptible to disease. By building heavy earthworks and siege weapons, the knights could throw diseased corpses and carcasses into the city and cut off access to food and water. Note: Siege weapons and archers are indirect weapons and this allows them to fire over earthen berms where they are safe from direct fire from riflemen.

2) Numbers. If the medieval force outnumbered the modern force by 1000 to 1 or more. The modern soldiers will run out of ammo before destroying the armored knights. In hand to hand, the knights would more than likely prevail and rifles with bayonets vs. sword and shield

3) Deceit: Pretend to surrender to the modern force and the hold a fete in honor of their great victory, then poison them. Pull the whole red wedding trick.

Answer 8

Short answer:

No way.

Long answer:

It's all about giving the modern soldiers handicaps.

There's a perspective on military technology that has been overlooked by the other answers, probably because it is too hard to control:

Modern militaries are (at least theoretically) bound to some rules. One of which is, that biological weapons are forbidden. This means there's a high probability of them not being prepared to fight against these kinds of weapons. To knights, illnesses are gods or the devils will, which means that it isn't unhonorable if an unholy enemy dies from them. In the medieval age, if one of your peasant soldiers got sick, you'd either kill him yourself or send him over to infect the enemy. I'm not sure where, but I think I remember having read about dead soldiers being shot into enemy cities by catapult. hasn't much to do with it, but an article about the plague as a weapon. You'll definitely find better sources about this kind of warfare, if you invest time searching for them.

Medieval swords will not match up against guns, but medieval illnesses have at least the potential to do so. There are many illnesses that went extinct because of better hygiene and control. Modern medicine never had a chance at learning how to cure them, so there surely won't be any vaccines ready against them. You could invent a new illness that isn't affected by antibiotics. To make it unsuspicious and knightly at the same time, the knights had to:

• Travel far and find an infected/cursed organism to lock it down.
• Infect themselves in thousands.
• Run into the enemy lines
• Die horribly by getting mowed down.
• Let animals in the area feast on their corpses.
• Wait and hope the animals would infect the modern folks.

If you really want a battle with swords vs firearms, your knights could attempt a finishing blow, by riding into the almost empty enemy lines, slaughtering the rotten flesh that's left over.

Edit: Or game of thrones style, have love interests, one from each side, to carry over whatever kind of illness you might want.

Answer 9

Lots of booby traps (ex: quicksand moats) and dirty guerrilla style fighting is the only chance. There are always various methods of winning without all-out fighting, such as religious conversions of the enemy or highly charismatic diplomacy.

Answer 10

Logistics

As others have pointed out, this is impossible with a full combined-arms modern army with air power, armoured vehicles, artillery etc. So what happens if you break the supply lines?

Take a modern army unit with guns but without vehicles and air power. Perhaps there's been a crash in the world oil supply or something. They are then unable to move around easily and only have as much food and ammunition as they can carry. If they have a fortress, they're besieged. They can probably hit you with mortars, so you have to stay a distance from the fortress. But as soon as they come out on the open plain to do something, such as forage for food or capture a village, you're more maneuverable than they are and can overrun them one platoon at a time.

The first few months of the war will also have a lot of phantom attacks in, to encourage them to waste ammunition. You're training them to hold fire for as long as possible while you get closer.

Answer 11

A medieval knight and a modern soldier are surprisingly equally matched.

The knight is a professional soldier, well trained, and willing to kill to achieve his goals.

The soldier is a normal guy, given a gun and told to guard this area or something. He is not prepared to kill at the drop of a hat and unlikely to actually fire for effect before the knight, some guy with a sword and armour, is within five meters.

From five meters away the knight can strike quickly… possibly the soldier will have time to fire and hit the knight; but inexperience and the general surrealness of being attacked by a knight will give a huge surprise advantage to the knight.

Of course, that wouldn't apply to SEAL or SAS, any elite unit, training makes a huge difference. Normal people hesitate to kill unless in immediate self defence. A huge part of modern soldier training is handling that reluctance; by training them to know when to do it and to actually do it.

To make a medieval army able to face a modern day army… massive numerical advantage. On the order of one medieval soldier for every bullet on the opposing side.

I'm guessing that should be enough, based on nothing at all, but unless it is a small modern army they will run into problems with:

Supplies: medieval armies can't deliver food to that many soldiers.

Hygiene: medieval armies suffer from disease, worse when they are larger.

Morale: after five hundred of your mates have died for no apparent benefit a soldier might consider deserting.

(Ingrates, don't they know that with only a few thousand more casualties the enemy will start to run out of ammunition.)

Answer 12

Space Shields

In the game Knigths of the Old Republic the justification to have people running around with swords and maces while flying spaceships, was that a personal shield agains lasers and high velocity slugs was at a point that a group of well trained swordsmands could contest against a great number of soldiers for a position, without a way for them to inflict any damage or to stop them.

You could give your knights the same barrier. But should be taken in consideration that modern infantry no longer works alone. Support artillery and Close groud support from aircraft are decisive in battle.

Making the terrain where you are using this tactic closer to urban warfare and far away from a glorious charge being vaporized in seconds thanks to an artillery barrage.

Answer 13

The Only way your knights may prove a force to be reckoned with is to have them wear fully encased invincible suits of armor. They would still be vulnerable, the people inside these suits of armor, like you have to take a shit or a piss once in a while, you gotta eat and more importantly, you also have to have some sort of invincible and ridiculously capable gas mask incorporated within the armor suit, because you have to breathe and smoke and poison gases are a real danger.

This way you can have knights charging through an artillery barrage, stepping on landmines, getting thrown around the battle field and still be able to get up and get into mele with their opponents.

Answer 14

Okay, first an important question: Are we talking about a medieval army somehow transported into present day? Or a modern army somehow transported back into medieval times? Because it makes a huge difference. If it's the latter, many of the advantages that modern armies have would be severely handicapped. For example:

• Lack of vehicles and air support - even if a few planes and tanks got transported back, they'd quickly become useless as the fuel ran out and there'd be no easy way to replace it back then.
• Lack of ammunition - those fancy rifles and machine guns will only last until they empty their ammo. Hiring a blacksmith to create bullets capable of being fired from a modern weapon might be possible, but more likely than not, you're going to damage them beyond easy repair the first time you try. The machining tools available at the time would not have nearly the level of precision required to replace parts on a modern weapon.
• Lack of GPS and radar - Tactical operations are heavily dependent on modern infrastructure, being able to figure out exactly where you are and more importantly where the enemy is would be much more difficult lacking the satellite network and electricity to power any other types of detection devices.
• Lack of food - You might have brought back enough rations to hold out for a little while, but it's going to run out, and you're going to have to resort to hunting for more, or trading with the locals, who aren't going to be impressed by your future-money or your gadgets that are mostly useless without electricity. Acquiring enough food to feed an army used to having an inexhaustible supply of easily accessible food from the local supermarket will be a challenge.
• Lack of local knowledge - Not knowing the lay of the land or earning the trust of the locals will make it hard to get by on your own. Depending on how far back you go, you might not even be able to understand the language they're speaking. (Try listening to Old English sometime, you won't be able to make heads or tails of it.)

All of this pretty much only applies in the "modern army transported back in time" scenario of course. If it's "medieval army transported to the present", they'd likely stand no chance at all.

Answer 15

I've noticed the question was not about withstanding a modern army, but just soldiers.

So the answer would be tactics: pick the place and the time - wait for a sandstorm, then attack. All the long-range advantage of riflemen and snipers will gone due to bad visibility conditions. Infrared recon and satellite imaging will be useless. And modern fire-weapons tend to jam with all that fine sand sticking to oily parts.

Maybe make the modern army soldiers to expend their limited ammunition, while at the same time cutting the supply routes. Modern infantrymen only can carry a small amount of rounds, because ammunition is ridiculously heavy: 1000 rounds of 9x19 weigh 13kg. And all their modern weapons will be useless without ammunition replenishment. A sword will still work.

Level the playing field: force the modern soldiers into something resembling ancient armour, with increased weight and limited field of view: spread radioactive contamination. I'd suggest β emitters (not airborne particles, but resident on the ground). Ancient metal armour might make a better shielding than olive-drab rubber suits, while at the same time maintaining better cooling (because the medieval knights won't be drowning in their own sweat).

Answer 16

George Washington's army could slaughter your knights in a stand-up fight.

Every generation of military tech is designed to defeat the last few generations. So you have to avoid stand-up fights.

I think our best precedent is the Scots wars against the English, where a variery of asymmetrical methods were used, sich as preparing the battlefield or repositioning, along with the old Scottish Charge on an ill-prepared rear area.

A big part of why the Scots won is they were fighting on their home turf. Each of these fights had homefield advantage as a factor.

These battles would be routs. They would have to be; because if the modern army got on their feet, it'd be a rout the other way. From the knight's perspective, it would be like fighting the Borg. The moment you lose initiative, you lose.

Captured weapons

After the first rout, the knights will get their eyes opened. They will have to make a choice: adopt the modern weapons, or walk away from them.

Now you'll have knights that look an awful lot like modern soldiers.

Whether that works with the romance of your story, I do not know; but strategically, if the knights ignore the opportunity, it would largely seal their fate.

At this point, you have a rather unromantic modern asymmetrical warfare, such as Vietnam or Afghanistan.

Answer 17

For a knight with a sword to be effective, he has to get within melee range in the face of direct gunfire and explosives. Small arms fire may be survivable with very heavy armor or perhaps even a heavy pavise-shield to hide behind, but a grenade is going to wreck his day.

Armor that can withstand assault rifles, heavy machine guns, and grenades is not really man-portable. The modern version of heavy armored cavalry is... a tank. Bullet-proof but you need a vehicle to carry it around.

The closest medieval analogue to a tank is probably a siege engine. Towers for scaling walls were armored against missiles and flame, and could be pushed forward, serving as a shield to those behind them. Medieval sappers would also use movable shields to protect them as they dug under walls. Such mantlet-type devices might conceivably be made effective against guns or even grenades, allowing slow forward progress toward the front line.

Once you get within melee range, a sword is a deadly weapon, especially against cloth or kevlar. A spear is better, and just as knightly as a sword. The real problem is getting within range. Don't forget that guns are still useful at point-blank range, and the enemy soldiers will have knives and some hand-to-hand training. Your knights will need to strike fast and make that first blow count, to avoid getting shot in the face.

Even so, while pushing a mantlet might be effective for WWI-style trench warfare with established lines, modern warfare tends to be highly mobile. It won't do any good to reach the enemy position if the enemy simply falls back, or hops in an APC and moves elsewhere before you can hit them.

A heavy machine gun is probably going to tear a mantlet apart unless it is very very heavy, so I wouldn't rely on taking down machine gun nests with this method. At most you might keep them busy while your real attackers sneak around behind them.

Heavy crossbows could serve to pin an enemy down at range, in the same manner as guns, although they are much slower. A major problem is sticking your head out long enough to aim and fire, in the face of a machine guns and snipers. You might also need a squad of people to reload and cock crossbows fast enough to make them a credible threat.

While crossbows are similar to guns, archery works differently in that it is indirect. A crossbowman needs to show his face to get a direct line of fire, while an arrow is arched over an intervening barrier. The archer is not exposed. This provides a distinct advantage if you can use it.

I think the best options available are:

• Hold a defensive position. Don't attack them, they move too fast. Instead hide behind an impenetrable stone wall and make them come to you. Arrange it so that they won't even see you until they are in sword/spear range.
• Your armor won't help you so you might as well shed it, unless you just like wearing it. They only benefit is if you are facing someone with a knife, but since you have a sword they probably aren't much threat anyway.
• If you absolutely must attack a fortified position, push a heavy mantlet in front of you. Or better, use your horse to move it, since the horse is useless otherwise. Also, outnumber the enemy. Even a gun can only kill so fast, and with enough attackers you can overwhelm or flank them. You can't kill us all...
• Archers. Put your archers behind a wall where they can't be hit by gunfire, and then darken the sky with arrows.
• Siege. Tried and true, and it forces them to come to you to break it, giving you the defense advantage.
• Asymmetrical guerilla warfare. Not so knightly, but desperate times call for desperate measures.

Answer 18

Give the medieval army guns. It's the only way.

Answer 19

How do a you make a knight with armour and a sword formidable against a modern-day soldier with gear and a gun.

There are many weapons other than offensive weapons. Think of deception, concealment, asymmetric warfare, logistics and so on. So:

• How about an ambush, close quarter combat which renders modern equipment useless
• Concealment or deception, perhaps trick the modern soldier into a place or action that she/he is not prepared for
• Logistical warfare - perhaps the knight could disrupt his supplies, or draw him to a place where the modern soldier would be weak.

And how would you make a medieval army formidable enough to face a modern day army

Again you need to work your advantages to their disadvantages. It is difficult to think of disadvantages of modern militaries, but here are a few:

• economic expense - modern militaries are tremendously expensive. Disrupt their economy, their fuel, their supplies to make it even more expensive to run. Perhaps medieval armies are cheap in comparison, requiring no investment and no technology.
• size - modern militaries are large. They are also slow to react and cumbersome in certain cases - the medieval army could use this against them by being nimble, conceal themselves, be everywhere and nowhere.
• over-confidence - many modern generals may be overconfident on what they see is a 'done deal'. This is their weakness, and as such could be exploited. Lure forces into easy traps they do not expect. Let them use 'shock and awe' tactics where they are least effective.

It's going to be difficult but if the commanders of the medieval army are inventive enough, and their will to fight and spirit is high, then there just may be a chance they could prevail.

Answer 20

How do a you make a knight with armour and a sword formidable against a modern-day soldier with gear and a gun.

1. Better knight armor was made in layers and was shaped to deflect blows where it could not simple absorb them. Build it to deflect rounds, like it was done to tanks. Of course that means being hit at a give location from certain angles is fatal and from others completely survivable.
2. Change tactics. Walking towards a machine gun nest slowly in the open on daylight is not advisable.
3. Redesign armor to match new tactics.

And how would you make a medieval army formidable enough to face a modern day army.

1. Guerrilla warfare, force modern army to fight your battles, not theirs. Look at all the cheap but effective things Vietcongs did to US soldiers.
2. Learn enough of the modern army to understand its limitations, and explore them. Hence Guerrilla.

Answer 21

OK, This is the historical answer. This was probably the biggest military upset of the 20th century: Battle of Dien Bien Phu The TLDR version is that the French adopted a "hedgehog" strategy; they camped defensively and expected to rout the Viet Cong [I will call them that for now]. It does show that a somewhat greater force in number [the VieT cONG] can win against what should be a more modern, professional army. If your knights could have some situation comparable to what went on here, then maybe it's their best chance.

Answer 22

Rule #1: Lose the armor.

Medieval armor had enough trouble against Rennaisance-era musket balls - and arguably, the proliferation of even primitive firearms was the last nail in the coffin for the era of plate-armored knights.

Against modern rifles with AP rounds, a suit of medieval armor might as well be a large mobile coffin or a ball-and-chain around the ankle. Sell it to a museum. It's ineffective or outdated.

Rule #2: Maces and morningstars are your friends. A good metal quarterstaff isn't half bad either.

Modern combat armor is designed against bullets and combat knives, so the best chance of countering that with medieval technology is blunt-force that smashes or knocks out whatever it comes into contact with.

Rule #3: Corner-camp and abuse the environment.

Your armor isn't effective, but there are plenty of things in the environment that you can use to your advantage. Hide behind thick stone castle walls and ambush the enemy around corners with a mace or hammer. Use trees as cover, use thick foliage to hide yourself. Sneak and be stealthy. Be creative.

Rule #4: Bring fire support

Fortified longbow/shortbow formations might be more effective than you think at providing suppressing fire. Mix on some hidden crossbow guerillas on the enemy's flank. Bear in mind that this won't work against tanks or air support obviously.