TL;DR: If I am insistent on a nation having a single weapons system spread throughout all of its troops, how much of a technological advantage is necessary to conquer the benefits of the enemy having combined arms?

I asked this Most Effective Ancient Weapons System if Combined Arms isn't an option question about a week ago, seeking an answer about which weapons system would be most effective if combined arms weren't an option. The ultimate conclusion was that combined arms will always prevail, because they can cover for each other's weaknesses and provide more flexibility, while a single weapons system will always have weaknesses.

However, for story reasons I really want one of my nations to use a single weapons system (not necessarily a single weapon, mind you, but all use the same system of weaponry). Given that it seems combined arms will always prevail given the same level of technology, I have decided this nation will need to have a more advanced degree of weapons tech to make this feasible. They are somewhat isolated, so it is completely plausible they could be ahead of their neighbors in technology, which would become apparent once they are attacked.

It is certainly true that a tech advantage with one weapon can beat combined arms. For example, we could have a caveman tribe with a combined arms military, made up of Og, who hits enemy with stick, Bog, who throws stone at enemy, and Pog. Pog use teeth. The caveman army has fifty of each. On the other side, we have fifty US Marines, all armed with modern rifles. While one side is significantly larger AND a combined arms military, there is no reasonable argument for them having a tactical advantage in any foreseeable battle situation.

However, this wide of a technological gap doesn't make for an interesting story. Therefore, what is the smallest tech gap that can make up for having only one weapons system, preferably not going any higher than medieval technology (as this is a fantasy story)?

Current thoughts include an army of bowmen while the enemy nation has no armor, or hoplite style large shields with armor while the enemy is clad without armor and largely dependent on projectile weapons (many historians say this is a primary reason the Greeks won the Persian wars, as the Phalanx was especially well suited to the terrain, as well as a counter to Persian tactics). (And yes, I know the Greeks had more than just Hoplites here. The point remains that the famed Persian bowfire was reduced in effectiveness by hoplite armor, and the Persians were not prepared to take them on in hand to hand fighting.)

Again, I recognize combined arms are better. Seriously. I get it. But I want this army to have one weapons system, so I'm going to give them a tech advantage. If you still don't think they can beat a combined arms enemy, then you can stand with Og Bog and Pog, while I go with the Marines, and we will see what happens.

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    $\begingroup$ To further an argument for single arms: medieval war was fought with what was at hand. Wars were unbalanced in both numbers and units at their disposal. Combined arms seems to think everything is neat and balanced, but most battles were incredibly onsided slaughterhouses until surrunder. Combined arms might not be required in many of these engagements. For stories incredibly boring, but if you can grab 10000 spearman against 1000 combined arms troops there was often little doubt who would be the winner. $\endgroup$ – Trioxidane May 27 at 6:14
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    $\begingroup$ I am confused. What is a "weapons system"? $\endgroup$ – AlexP May 27 at 7:17
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    $\begingroup$ "There is no reasonable argument for them having a tactical advantage in any foreseeable battle situation": Oh really? The primitives would have a clear advantage in any situation where the marines cannot use their rifles. For example, in dense jungle. Or where the terrain favors the low-tech defense by providing opportunities to hide in ambush. And so on. Didn't the glorious American army learn this lesson in Vietnam, with a recent refresher course in Somalia? (And those famous archers were Parthian. A different dynasty, some 3 or 4 centuries after Marathon and Salamis.) $\endgroup$ – AlexP May 27 at 7:22
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    $\begingroup$ @AlexP anything ranging from having an army of machine guns with powder and bullets to just having pieces of wood to bash each other's head in. The system is in how it's distributed and used. $\endgroup$ – Trioxidane May 27 at 7:24
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    $\begingroup$ A quick eyeball of the casualty guesstimates on Wikipedia says the US inflicted a ~19:1 KIA rate on the PAVN/VC. And remember that the context is ancient history so, unlike that conflict, the querent's scenario is that of total war, permitting unrestricted destruction of infrastructure and civilians by both sides to reach victory. That would have had a good chance of tipping the scales the other way. $\endgroup$ – GrumpyYoungMan May 27 at 13:25

To answer the question - the answer would really be zero.

There's much more to warfare than simply technology, or even what arms you are using. The following also contribute substantially to an army's success:

  • Command - this is in many ways the biggest factor. Sun Tzu mentions that a good commander is worth more than any other component of warfare, and good officers too. An army that has a strong will to fight, and is well fed, supplied, coordinated and organised, is due to the command structure.
  • Training - having troops that are well prepared for all scenarios, can work flexibly in large or small groups, while retaining your 'single' non-combined arm (whatever it is) will enhance their effectiveness.
  • Intelligence - knowing something your enemy does not gives you a huge advantage. Even simply knowing where they are, whilst your enemy does not know where you are, can turn the odds in your favour. You can deceive them, surround them, confuse them, split and divide them into smaller pockets, intimidate them or defeat them on your terms.

So the above means you can have well-trained, well-commanded troops with good reconnaissance with, say clubs, decimate well-armed troops with, say swords, but who are poorly disciplined, have bad communication, not knowing where they are or where the enemy is. In fact, history is replete with examples of this already:

  • Mongols, using only horse and bow&arrows, completely outwit and outmanoeuvre much more well-armed diverse opponents. Their command and control was really tight (with 10 archers to Arban, 10 Arbans to a Zuun, and 10 Zuuns to Minghan) allowing flexible grouping or splitting to surround or divide opponents. Their intelligence was excellent, with fast scouting commonplace, and also their commanders intelligent, with for instance getting troops to create huge dust clouds so their opponents think their army is much larger than it was.
  • The Battle at Agincourt - although both armies had diverse arms, the main factor that caused the numerically superior French to lose was their poor command structure. Used to acting alone, superiorly armoured and well armed swordsmen and horsed knights were inadequate against well coordinated but lightly armed opponents who mainly fought with an assortment of melee weapons, but crucially were better prepared for the terrain and better commanded. (yes 80% were archers, but there is some controversy over how much effect the longbow really had compared to the melee weapons they also wielded)
  • Alexander the Great - up against far more numerically superior opponents (sometimes 4 times his own) he mainly used spears to great effect by manoeuvring his forces in advance to prevent flanking by enemy cavalry. Ie. by being prepared, and by spreading his spear forces wide, enemy horsemen could not use their primary advantage of attacking a flank or rear, and so were forced to do frontal assaults (which or course for a horse is terrible against spears). Spears were also superior against elephants helping him conquer India. Amongst other qualities of leadership, his ability to preempt common tactics of the day yielded victories and he never lost a battle.

So in summary, given so many factors that influence the outcome of a battle, actual armament is only one of many of them. So, given the above examples, the minimum difference in armament technology for a singular armed group to be superior would actually be zero.

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    $\begingroup$ Alexander's army was a perfect example of combined arms. Spears for holding, Shock cav for crushing, light foot and horse for scouting and wing covering - it is completely unsuitable for what OP wants. $\endgroup$ – Archelaos May 27 at 8:43
  • $\begingroup$ @Archelaos I suppose my point here was that arms was only one factor. Alexanders opponents could have similar disposition, but it was the authority and intelligence of command that made the difference. $\endgroup$ – flox May 27 at 8:45
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    $\begingroup$ Speaking of Sun Tzu, shouldn't logistics be listed as the #1 alternate tech factor, particularly in the context of ancient-history? Logistics and supply (e.g. agricultural tech providing more food allowing larger armies to be fielded) are vital to an army. $\endgroup$ – GrumpyYoungMan May 27 at 13:47
  • $\begingroup$ I'd quibble about the specifics of these battles (it's what we do around here) but overall the answer is right on the money. $\endgroup$ – DWKraus May 27 at 18:43

Frame challenge: just field superior numbers

Battles of single arms vs combined arms can be won by sheer numbers. Numbers can nullify many tactical advantages like flanking or breaching formations. Other tactical advantages are reduced by just having those numbers. If an archer kills one of your troops, it's not as effective in relative terms as in a smaller army. Every enemy needs to be more effective to make a dent.

In the meantime you have more advantages with just having numbers. Flanking and breaching is much easier as you just have a larger front. Morale is likely much higher, as they can easily see they outnumber the enemy, while the enemy realises they need to kill a lot to win and their morale drops.

There are many advantages outside combat as well. You're able to split forces and take multiple tactical positions, denying resources, maneuverability or the like to the enemy.

How to get superior numbers

To get higher numbers you can have it mandatory for everyone to train with the chosen weapon once a week or more often. If possible, like with spears, to make it themselves (or just at the smithy) but at least maintain it. Have older people teach them some manoeuvres as well on the training day. With the tax collectors you can send someone to inspect the weapons and do some advanced training.

This way you have a (semi)trained force ready. They have grown up to know that they might be called upon, they'll feel a lot more ready than hastily armed and trained soldiers, so you'll have less runaways and they know some tactics. They know where to build a laterine and how to stay in formation. They already have weapons, making arming your soldiers not a bottleneck. With these factors you're likely to have, at least initially, a larger and better trained army than your opponents. There can be some downsides, like that you really don't want to piss off your own population, as they are armed and trained.

Why not an incredibly advanced medieval weapon?

As you say, combined arms is a better strategy than single arms for equal opponents. With medieval weaponary there is too little power difference between the single weapons to defeat combined arms most of the time. Even if you grab only bronze weapons for the combined arms and you get the latest sword technology at the end of medieval ages for the single category, the tactics of combined arms are just too important. Even if you would win 55% of the time you wouldn't call it a sound win. Numbers and better training of a large part of the army on the other hand have always given advantages*.

*I did skip disadvantages of having a larger army, like food supplies, camping sites and others.


You mention yourself that you know it's terrain dependent, so you'll have to consider the terrain when making your decision on this.

The two examples that come immediately to mind are:

  • Tanks in WWI - There was no significant technological difference between the two factions, but when tanks came to the field they were overwhelming to the combined arms of the day, trenches, infantry and artillery.

  • Full Greenwich plate armour before firearms - Again no significant technological advantage, just resource, skills, and cost. The last being a critical factor in this example. Access to the Greenwich armoury was a boon given only by the monarch, but if the entire army was outfitted this way (and appropriately trained) the advantage conferred would be significant.

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    $\begingroup$ Tanks in WWI is not nessicarily the best concept, as once the combined arms force got over the initial shock, they worked out ways of disabling the tanks by using infantry to attack the tanks with granades and anti-tank rifles. Tanks had to be used as a combined arms force with infantry to be effective. $\endgroup$ – user1937198 May 27 at 14:50
  • $\begingroup$ @user1937198, it still works well for this specific scenario, giving the attackers a shock on first contact, without being too much in the long run. $\endgroup$ – Separatrix May 27 at 17:09


Ok, the earliest gun aside from tenth century Chinese experiments is the Arquebus gun or something similar. These are very early, very simple, muzzle loaded, smoothbore, long guns. These are slow to reload, expensive to produce and maintain, and require specialized training. You can put a bayonet on it to make it a spear, which makes it not totally useless in melee. However that is more covering your ass and less making it a well rounded weapon. So why are they a good weapon?

One shot, one kill.

The one upside that the gun has is its pure lethality. One hit will kill the average person, and that's even if it hits a non-vital area. The weapon is not accurate at range, but if you fire it at a group it doesn't need to be. With longer range even with a long reload you might get two shots before they reach you, giving you two waves of dead people before the enemies can reach your spearmen. They are excellent defensive weapons, their original purpose, and decent offensive weapons at middling range. They counter, or at least ignore most shields and armor. They don't deal with melee fighting tactics. They can take care of Calvary and ranged attackers. The biggest problem with the weapon is that it is expensive and hard to maintain. If your nation discovers interchangeable parts and the vertical integration a few centuries early they could mitigate these problems. It might turn out the reason they use only this gun is because after modifying their production capacity to support guns they literally don't have the capacity to produce other things as literally everything is tied up in making as many of these guns and bullets as cheaply as possible.

Limitations or why not everyone uses them

Depending on how good your troops are it takes between one to three minutes to reload the gun. Depending on the reload time the distance you need to get to to ambush them changes, but ultimately has the same result. If you are close enough they will not be able to load a round before you reach them. If you are fighting veterans, you can ambush them less than 100 meters away. If you are fighting new recruits you can ambush them from 250 meters away. Calvary will be able to do this at one to four kilometers depending on how good the loaders are. Furthermore, if you use trenches, cities, or other things as cover to get past the first volley, all you need to do is bring about as many people as the people you are fighting. Spears are better than bayonets since the gun is slightly more unwieldy. Any other combined arms tactics are just icing on the cake. Any fighting in cities or castles will favor people with closer range weapons that are easier to maintain over time.


If you have guns and your enemy doesn't you will beat them about as often as they beat you without having to worry about army composition. You will still get Battle of Islandlwanaed occasionally, but so long as you always walk in the middle of open fields and stay stocked up on ammo the odds are in your favor. The one upside to this is since you know your weapon's down side you can easily remember and avoid it. But if you do have to fight in cramped streets or thick forests your weapons will still be mostly effective.

  • $\begingroup$ Arquebus is a fairly vague term. Just to be clear: you're talking about a serpentine lock? $\endgroup$ – Andrew Mellor May 27 at 15:50
  • $\begingroup$ Yeah, probably. Or something as equally primitive and ineffective by modern standards, but the height of technology in the middle ages. $\endgroup$ – Charlie Hershberger May 27 at 17:13

There is no general answer.

First, I have no idea what you think a “weapon system” is. Using modern US DoD terminology, what you asked for would most closely mean a single variant of a single type of weapon. So e.g. the M4A1 carbine no body armor, no radio, just a nude dude with a gun. Something like “all flavors of F-18” night instead be a “family of systems.” If you mean, like, guns that run on smokeless gunpowder, there isn’t a clean term for that. Maybe that’s a “single technology,” but no-one really talks about that. If that’s what you’re looking for, you want something like Heinlein’s “the sixth column,” wherein a small number of holdouts discover a new magic technology and use exclusively that to defeat a large invading army.

Second, “winning” is very much a product of the overall political situation. France lost a war in Vietnam (immediately before the US tried) after winning every fight and holding all the ground. Then those same soldiers shipped over to Algiers, “won” even harder, and in doing so threw France into such turmoil that the whole government had to be dissolved and reformed. So: did Algerian separatists win that? They certainly lost every engagement, hard. Same question with Napoleon and Russia: he conquered everything he touched there, and his enormous army starved to death. But his army was essentially undefeated: did he “win”?

Here’s what you actually need: 1) Make up a scenario where the world is in some state, and you want it to be in a different state. Figure out how your guys will transition from the current state to the end state. (2) Pick a specific combined-arms force that will try to prevent that transition. You can pick something real or make something up, but for something made up, you will need to figure out capabilities and doctrine. (3) figure out how your guys will prevent the other guys from interfering. You’ve added a constraint that your guys can only use one weapon system to accomplish this.

But (3) only makes sense in the context of (1) and (2).


I would go, if you have a certain tech level advance, lets say late medieval vs antiquity, for units like :

  • Genova Shielded Crossbowmen : Big heavy square shield that can stan on its own, plate-armoured crossbowmen, and equip them with longswords for close combat. You get an massive shieldwall while taking down anyone who dare come at range regardless of its armor


  • Plate-Armoured Arquebusier, do not underestimate the fear factor of a deadly new technology on the battlefield. If you civilisation could sustain it, I suggest to make them mounted on horses. First, thunder-like bullets rain, creating an smoke screen from the shooting, then a good old-fashioned charge. I bet that your Og Bog and Pog tribes would break their lines an flee soon after. That's one oh the reason how a few spanish troop could take down empires when they discover america. (There are a lot of other factors, but that not the point here)


The issue with combined arms is that you can always design a specialized troop composition which can counter most set ups. You can use horse archers, or heavily armored shock cavalry, or heavily armored knights, or elite spear units, and you can counteract them decisively.

What you need to handle that issue is numbers. Arquebus fit that. They're from the fifteen century, so they're a medieval technology. Guns are easy for anyone to use. Point and shoot. They can hard counter armor. You can easily equip vast armies of peasants with them. You can make them melee capable with a bayonet. This lets you quickly replace broken armies and always outnumber your enemy. Even if they have a clever counter, enough numbers can overwhelm enemies.

Setups that won't work.

Bows and crossbows. It's not that hard to make a wooden shield, which can counter bowmen, and armor is pretty easy to make. Once you're in melee range you can crush them. You can fight them in the rain, when bow strings work less well. You can use artillery to out range them and bombard them from afar.

Hoplites. They have a very strong front, but they're very vulnerable to flanking. Broken terrain makes them very vulnerable to melee troops. Thrown missiles tend to disrupt the formation and allow swordmen to crush them, as they can move better than spearmen. Disciplined enemies can counter them with good maneuvering.


Ideally, you want your single weapon system to have both ranged and melee capability.

For example, Roman legionary infantry had javelins for ranged combat and swords for melee. As long as you stay out of large plains where missile cavalry and shock cavalry combo would make short work of them you should be relatively safe.

The other option is firearms with bayonets. You can stay (late) medieval-renaissance tech levels just adding slide on bayonet - it is not that difficult to produce, so it is actually surprising it was not introduced earlier. If other side do not have firearms, you have major advantage, as you negate advantage their armoured elites would usually have.

On the other hand, swiss pikeman (using not only pikes other polearms as well) but in a world without artillery and firearms could work well. At least as long as enemy do not have massed archers/crossbowmen


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