Defeating Late Japanese Armor - Tosei Gusoku (当世具足)

Defeating Late Japanese Armor - Tosei Gusoku (当世具足)

A section of the famous ukiyo - e "ten brave takeda warriors" -武田勇士揃 by Utagawa Sadahide.

This was an article that was requested and one that I've really enjoyed writing, although it took a lot of efforts and researches.
It is a follow up of my complete analysis of the heaviest possible configuration worn by a wealthy samurai during the late 16th century, Tosei Gusoku (当世具足) - Body Coverage Explained; if you haven't read it yet, I highly suggest you to do so in order to better understand this topic.

So today I will cover the various way to specifically deal with that type of configuration and how it was done historically during the Sengoku period.
Before start, I will do a quick recap on the main weakspots of the armor:

A sketch of the most protective possible configuration of a late 16th century tosei gusoku. I'm not an artist but all the armor pieces you see are based on real pieces found in museum, private collection and so on that are available on my pinterest page for reference.

The main openings are the palms of the hands, the space in between the helmet and the mask and the space for mouth, and if someone is able to get around the tassets ( the kusazuri - 草摺) the upper legs and the groins.
Other weakspots that could be bypassed are the ones covered with flexible armor like mail or kikko brigandine; the inner part of the arms, the armpits, and the back of the legs and knees.
Another point worth mentioning is the fact that in there is an uneven thickness across the armor to save the weight; the face and neck, the upper arms and the legs are usually covered with thinner metal (0.7-1.2 mm) compared to the breastplate and the helmet, which could reach 2.5 mm or even more; this is important for the sake of this analysis.


Ranged Weapons

The Third World Kyudo Taikai (Tokyo) 2018 Demonstration were a group of reenactors perform battlefield archery known as Koshiya Kumiyumi - 腰矢組弓 . Taken from here.

When it comes to the ranged weapons of the period, namely the bow and the arquebus, there are some consideration to do.
The first thing to say about the bow is that all the armor is essentially arrow proof behind the 30 meters range. In fact, despite the power of the Yumi, the well forged plates and the deflecting curvatures are too much to bypass.
This is also backed up by Musashi's book of five rings, in which he explicit says that in a battlefield scenario, the bow "was unsatisfactory if the enemy is more than 40 meters away " exactly due to armor being involved.
Within the "close quarter range", so in the 20-10 meters scenario, it might be possible for a very heavy war arrow to pierce the thinnest parts, like the kote, the menpō or the haidate, although in these cases the plates are curved and this fact alone could prevent the arrow to penetrate.

In any case, the penetration will be very mild and might not even bypass the silk robes worn under the armor.

A Japanese arrow head of the Togari type; only these types of arrows could slip trough mail.

The only instance in which a bow could create some injuries is the scenario in which a mail section is hit (with the exception of the frontal armpit zone, since there is the double layer of mail and kikko manchira), or if the arrow manage to get stuck in between the helmet and the mask where there is indeed an opening.
However, the mail section are usually facing the inside of the warrior and are hard to access for an arrow shot, and hitting the eyes could be prevented by looking down while approaching archers.

The situation is much more different when arquebuses are involved.
Although these suits were usually bulletproof within 10 or more meters, this fact only apply for the helmet bowl and the breastplate.
If a bullet hit another area, like the limbs or the face, it is very likely to penetrate the armor unless the warrior is about 50 meters away from the rifle.
Although a bullet in the arm is not as deadly as one in the head, it could be potentially fatal; Ii Naomasa was hit at the right arm at Sekigahara by a bullet, either in the shoulder or in the elbow according to different accounts, and his death is largely blamed for that wound.
In addition to that, a point blank shot might bypass the bulletproof sections of the armor, but it is very unlikely and in any case the penetration would be minimal.

A tameshi zunari kabuto (試し頭形兜); in the picture it is possible to see the bullet marks.

However, if the arquebus in question is an Ōzutsu with a very large bullet, there is no chance that the armor might allow the wearer to survive at a reasonable distance. Such bullets were too heavy and too big and no armor could resist to them.

2 one hundred monme (百匁) size bullets; such projectiles were usually fired by those weapons and bypassed the armor as if it was nothing.

So when talking about ranged weaponry, only heavy caliber muskets ( and to some minor extent also arquebuses) posed a real threat for the warriors wearing that kind of configuration.


Percussive Weapons

Two warriors fighting with two kanabō, taken from the 絵本武蔵の鐙

Within the hand to hand combat, the situation is very different.
I've made a lot of articles which talks about different types of percussive weapons used throughout the feudal period in Japan, and how they were supposed to be good against armor.
In case you have missed them, I'm going to talk about the kanasaibō (金砕棒) (also known as kanabō) mace, the masakari (鉞) axe and the tsuruhashi (鶴觜) warpick which despite being quite rare, were the major percussive weapons used on the battlefield.
Just like with the majority of the percussive weapons of the medieval era we haven't any martial arts manual on how to use them and I have to use some interpretation in this case so please be aware that what I'm going to write it might not be entirely correct.

Despite the lack of martial knowledge, it is quite easy to immagine how such weapons were intended to be used: to strike with full force against the enemy in order to inflict blunt trauma through the armor.
However, maces and percussive weapons in general are not magical implements that could easily bypass armor as if it was nothing.
If we start considering a staff like kanabō, slightly tapered and long, with quite a lot of heft and a point of balance toward the tip, it is logical to assume that by using it like a sword or a quarterstaff there will be a lot of force transmitted to the target. 

A section of the famous "十二類巻物の書誌情報 " scroll in which a long staff like kanabō is used.

However, a lot of said energy will be absorbed by the armor which will likely dent and deform. The result is that the armor will be more or less damaged (according to where the hit has landed), but the wearer might not have been hurt that much; although it is better than nothing, blunt trauma is not as effective as a stab or as cut, unless bones are broken which is not very common when someone is protected by rigid armor.
Bending the steel plates that compose the armor is not easy in a fight and there are some zones that will negate much of the force because of the thickness, various layers and space in between the armor and the wearer.
One of these zone is the chest, which is protected by the dō (胴). In the configuration studied here, the dō is made with a sigle rigid well forged sheet of steel that encase the wearer; it doesn't directly touch the wearer with the exception of the shoulders and the hips where it rest, it is doomed thus increasing the chance of deflecting and behind it there are layers of arming garments that further increase the protection. A hit in this area might leave a dent, but it won't hurt the wearer.

Another zone like this is the head; the kabuto has a bowl which is among the thickest part of the armor, it is doomed and the head inside it is suspended so before touching the steel a lot of force would be deaden. Moreover, there is a layer of padding underneath.
However, the head is at the same time the target that reacts the most against blunt trauma, and a crack in the skull could lead to death or instantly disable the enemy.

So in this scenario, the most reasonable way to use a kanabō is to hit the limbs and the head especially at the temples area where the helmet is also closer to the head; the former are the targets that are covered with the thinnest armor, the latter is the most important target in a fight.
Hitting the limbs especially in the joints of the elbows, which are covered either by mail or a section of lames, could potentially break the arm or disable it for a while. The same apply for the hands, a precise hit with a kanabō is likely to break the bones in that area.
The arm itself has a lot of give when it is hit, so a lot of force is dissipated, but it would likely still be effective. Another target are the lower legs; a strong hit might bypass the suneate or even knock out of balance the warrior.

However, the most important aspect of this weapon is the length of the shaft, which could be used as a wrestling implement to subdue the enemy and locking him to the ground.

Once on the ground, a dagger could finish the job. In fact, this is the most realistic scenario in which two armored warriors could end.
Other versions of the kanabō like the shortest ones cannot rely on this feature and so are quite demanding in a battlefield scenario, especially given the poor defensive capabilities and the reach of a shorter mace; this is also why the two handed longer version were more common (despite still being rare).

A different scenario is on horseback; despite the many artistic representations of  later periods with warriors on horseback holding the two handed mace, we lack 16th century references of this kind of usage.
On a charging horse, a direct hit with the kanabō is a lot more devastating than on foot and hitting the head could be deadly.

An ukiyo-e depicting a kanabō being used on horseback.

All things considered, despite being a very effective weapon to destroy the armor itself by dents, the kanabō is not the best weapon to disabilitate the wearer behind it.

It is quite slow and it has limited area in which could deal severe damage in few hits, and require a good amount of space to be used. It can still be effectively used with bojutsu techinque but it won't be as nimble as it should, and except on horseback, its damages against heavy and thick armor are limited. This why it wasn't as commonly used in the 16th century as other, much more suited weapons.

Now let's analyze the masakari axe; much of what I've previously said it's still valid and even more, because despite the axe having and edge which could focus its force in a smaller area, it is usually less heavy than a kanabō. Some Japanese axes have a back head that could be used more or less like a mace but the aforementioned analysis is the same.
The blade, like the spiked kanabō, could potentially "bite" into the armor, but it won't cut through it and won't hit as hard as the two handed mace.

Some axes have a top spike which could be extremely useful, but their usage is more similar to spears and other polearms so I will talk about them later; for now, let's focus on the "average" two handed Japanese masakari.

A classic depiction of the masakari axe, from "春日権現験記. 第８軸".

Although usually the axe is not as long as a kanabō, it can still be used in the same way as a wrestling implement, but not as effectively mainly due to weapon being very top heavy and so not easy to maneuver.
However, the advantage of the masakari over the mace is the shape of the blade on top of the shaft; it could be used to hook limbs, armor pieces or the heads. Once that the axe is hooked at the enemy, he can be thrown to the ground,  the best solution to armored combat. Not every axe's blade is suited for this purpose tough, and hooking is not as easy as it might seems.
So the axe could be used as a percussive weapon and to gain advantage over the enemy by "hooking" his armor, but in regards to this feature there are weapons that could do it better.

Now let's move to the warpick. If we know very little about Japanese axes and maces, we know even less about this weapon. Interestingly, the majority of the surviving examples and depictions are one handed, short weapons which completely changed the scenario discussed until now.
In fact, if it is still possible to transmit some degree of blunt trauma through armor with the masakari and the kanabō due to their mass but especially due to their leverage gained by the longer shaft, it is very hard to do so with a shorter and lighter weapon like this warpick. With this in mind, it doesn't surprise that the majority of the examples of said weapon lack a "hammer side" and are usually very long and solid picks.

A Edo period tsuruhashi.

Unlike the other two percussive weapons previously analyzed, this warpick is meant to pierce and penetrate armor rather than crushing it. However, there are some issues that need to be addressed.
First of all, piercing through plate is not easy especially in the thickest part of the armor, moreover, the weapon is very likely to bounce due to the curvature especially when attacking the head or the torso.
The best targets in this scenario are the limbs and possibly the head, but while it might be possible to obtain penetration in the former it is highly unlikely to pierce the helmet to a significative degree in order to wound the enemy.
Second, if the weapon manage to pierce a plate, the chances of the pick being stuck are quite high and thus the weapon might be lost; this is why knobs were used on maces rather than very pointy spikes.
Yet it is fair to say that a warpick in the arm or in the leg is arguably capable of disabling a person, despite a rather shallow penetration.
However, what this warpick is capable to do that neither the kanabō or the masakari could is piercing through mail with ease. In fact, rather than targeting the zones covered with plate, it would be much better to try to hit the ones covered by flexible armor. In this case, the penetration could be severe and inflict serious damage.
This zones are quite hard to hit due to the way the weapon is handled, but it can be used to reliably defeat mail and possibly kikko brigandine.

Another point in favor of the weapon is that just like with the axe, since the pick is angled to the shaft, it can be used to hook although the rather short handle means that it would be very hard to subdue someone.
In fact the serious disadvantage of this weapon is its length, that paired with the very low defensive capability of the pick, explains why it wasn't used that much as far as we know.
These issues could be solved with a small hand held shield, although we lack accounts or evidences of said combination in the 16th century.

All things considered, percussive weapons are still quite valid against armor, especially in a battlefield context in which the blunt force could be used to concuss the enemy and open him to the attacks of another soldier; yet at the same time, the space and the energy required to use these weapons properly made them somewhat unsuited for the tight formations of the Sengoku period.
As counter intuitive as it might seems, these weapons weren't the first choice when it comes to deal with the armor analyzed.

Polearms

This is hands down the most viable weapon's category to deal against armor; in particular, I'm talking about the Japanese yari (槍), which is often translated as spear in English. Now, as I have already said previously, a better translation for yari should be polearm, because while it can be a spear, it can also be something more akin to a halberd, a ranseur, and sometime even more similar to a poleaxe rather than a simple spear.
This part of weapon history is quite complicated, but among the various types of yari it is possible to find ones made to thrust, to cut or specifically to bite into armor just as much as a tsuruhashi, and to cut&thrust.
It is indeed a multipurpose tool that can be used very effectively in the topic discussed here.

Two things that the yari has over the aforementioned weapons are the reach and the nimbleness; in fact a yari is usually longer and swifter than any axe or mace used in Japan.
The long shaft is still short enough to be used in a close quarter situation as a wrestling implement, like with a kanabō, but it would be less heavier and thus much more balanced in the hands. 
Moreover, even the simplest variation, a straight su yari (素槍), could spot two parrying hooks that are fundamental to hook the enemy or his weapon.
This alone could be enough to explain why the yari is the better weapon in this regard.

A simple su yari with parrying hooks.

Without going deeply into the various types of yari used during the feudal period, since there will be eventually a dedicated article in the future, it is worth mentioning the fact that some yari were indeed made to be used as percussive weapons, with side blades resembling axes or warpick, and in some instances even hammers.
So, to some extent, they could have been used just the aforementioned weapons, although they would have been lighter but faster.

A yari designed to be used as percussive weapon rather than as a spear. This design is called hantsuki yari as written in the picture.

However, the key point in favor of the yari is that, while it is not particularly good directly against armor ( a kanabō would likely dent severely armor's plates, a yari won't in most cases) it is extremely good at exploiting armor's gaps due to its spearhead.
A spear's wound through a gaps covered by flexible armor would be much more incapacitating than a bruise to the head or the limbs, not to mention that to cause internal bleeding through this type of armor with percussive weapons required multiple hits with huge force behind it (after all, rigid armor is the best solution against percussive weapons).
Not every yari had tips and points optimized to thrust through flexible armor, but some indeed had it and these ones were the best yari to use against armor.
This, combined with the other advantages, make the yari the ideal weapon and it is not a surprise to see that it was essentially the main weapon used on the battlefield by the samurai, whether on horseback or on foot.

The famous "Shiratori no yari - 白鳥鞘の鑓" associated with Tokugawa Ieyasu; said spear has a very fine and tapered point that could potentially thrust through flexible armor.

On horseback it is quite easy to see that the speed of the animal could increase the impact and thus the damage of a a yari's thrust dramatically, which could led to penetration of the plate or severe damage to the armor and the men behind it, so there is not much to discuss.
What is interesting about foot combat with a yari is that, unlike with the percussive weapons discussed above, we have extant techniques used to deal with armor. This, paired with the massive usage of yari among the armored samurai testify the incredible effectiveness of the weapon against armor.
For the sake of simplicity and space, I've excluded other polearms weapons like the nodachi or the naginata due to being rather ineffective against heavy armor like this one, save for few occasion.

I've tried to analyzed and sketch briefly the various techniques used by the Yagyū Shingan Ryū (柳生心眼流) in their Kacchū Heihō (甲冑兵法 - Armored art of war) set of techniques. Mind you, these sketches don't aim to be good representation, but they are meant to give a very general idea.

In this first technique, reading from left to right, the enemy is going to strike low, to either hook or cut the leg with his side blades. When he close the distance, use the lower end of the shaft to redirect his weapon, with a push or a hit in order to knock the spear out of the way:

Once is spear is to the side, he is open to the front. Thrust into his face with both hands in order to finish him. This technique could be applied to some extent with a kanabō or even a naginata, although a spear with a straight blade is likely to hit the eyes more reliably. In this position, it is also possible to hook the enemy head with a side blade/parrying hook and throwing to the ground or hit his head to the side full force with a side blade.

In this technique, both fighters are facing each other. Use a high stance in order to expose your armpit and allow the enemy to lunge and hit his weapon, or directly thrust your blade into his weapon in order to entangle it:

Once the blade are entangled, rotate the spear and redirect his weapon towards the sky, in order to expose his armpits:

Once his spear is pointed towards the sky, remove your blade from the entanglement by rotating it in the other direction and get low. From this position, if one his quickly enough,  it is possible to access with a strong thrust to the armpits, the face, or the side of the hips (if uncovered by the kusazuri).

There are even more techniques that I won't cover in this article, but the system is roughly this one. Unfortunately, researching those martial arts knowledge is really hard, as well as giving enough details through sketches.

Swords & daggers

I know that there is a lot of interest among sword's enthusiast when it comes to use swords against armor. However, to put it bluntly, in general swords are the worst weapons to use in this scenario (saved for very specific European design) because they lack the reach and the leverage to exploit reliably armor's gaps as well as the percussive power and the mass to seriously injury someone through armor.
Moreover, some swords are worst than others to deal with this very hard task, namely curved ones with broad tips, which is a good approximate description of a katana.

A typical katana shape with a curved blade and a broad tip. This sword design it is not very optimized to be used against armor.

Moreover, there are some famous koryū schools that have techniques used to deal against armored opponents with a Japanese style blade, but some of them are centered around cutting into precise spots like the internal portion of the arms, of the legs, the armpit or around the neck and throat.
However, these spots could be covered by armor! One of the things that is often misunderstood is that how enclosed late Japanese armor could be, and paired with the popularity of these aforementioned technique, the final result is that the picture is very distorted.In fact, just to show a quick example, a cut directed to the inside of the arm would do no damage when someone is wearing something like this:

Maybe one or two laces would be damaged, but there will be no blood loss at all due to the presence of mail.
Another big misconceptions is that the Japanese sword "is designed to cut the enemy's armor's cords and laces " that hold it together.
Again, this is quite ineffective since those laces were usually located into hard-to-reach spots as well as being covered themselves by armor. Not to mention that to reliably cut those laces and make the armor fall apart, you will need multiple cuts, so it's just better to aim for the already present weakspots instead of wasting time, energy and possibly your life in trying to create new ones. Not to mention that within this context, a tosei gusoku didn't have a lot of laces to begin with.

Of course said aforementioned technique could work in a different context, after all not every Japanese warriors on the battlefield had mail covering his armpits or insides of the arms, as well as a full kit of armor. A slash to a unarmored leg is much more effective and natural when dealing with less armored foes, which means the average threats of those battles.
Still, full armored combats with swords in a Japanese context is somewhat different to what is often portrayed and in this article I want to show you a bigger picture.

First of all, the sword; while the average (pop culturally speaking) Japanese katana born from the smiths of the Edo period is not suited to bypass the flexible armor used to cover weakspots in Japanese armors, some design might work better:

This example is a very peculiar Japanese sword, far from being common, but it is possible to see a very long and tapered okissaki paired with a shallow curved; this type of sword design is found in shobu zukuri or naginata naoshi zukuri blades, although my example is very extreme if you will.
Said sword could probably stand a chance when it comes to slip through mail rings covering the armpit for example, and it's the best design you could get to deal with armor when it comes to Japanese swords.

The second important point is how to use such weapons in the armored context and the answer might be familiar among some readers; using the point and try to reach those famous weakspots covered by flexible armor or not, using a hand to aid redirecting the blade (a technique commonly called half swording) and using the kashira (頭) of the sword (the pommel) to hit the enemy's face in order to lightly concuss him and create openings.

Murder strokes or using the whole sword by the blade and striking with the hilt is not something seen in traditional Japanese martial arts, but the if we look at the other techniques they are not too dissimilar to European techniques.
Below some simplified techniques taken from the Yagyū Shingan Ryū (柳生心眼流) in their Kacchū Heihō (甲冑兵法); again, since they are sketches of mine, the same thing said above is still valid.

In this technique, reading from left to right, both warriors are facing each other, with a low stance. As soon as the enemy approach with a downward cut or with a thrust, use the back of your blade to intercept his and start to rotate the weapon:

Once the rotation start, it is important to redirect his blade towards the sky, while closing the distance. Once his weapon is pointed in the desired direction, lower the body in order to access to the armpits:

From this lower position, if one is fast enough, he could thrust the blade under the helmet into the face or into one of the armpits. To aid with accuracy, it is possible to allow the blade to slide on the attacker's shoulder or grab the blade on the back with the other hand and use half swording.

In this technique, which is also found in Tenshin Ryū (天心流), both opponents are facing each other with a mid height stance. Once the enemy attack, parry with a static block and aid the maneuver with the hand on the back of the blade, while assuming a lower stance:

The action should then be very quick; use then both hands to "pivot" the blade and put the opponent's sword to the side, and then while grabbing the blade and using halfswording, close the distance and thrust to his head. Otherwise, use the other side of the blade while rotating and hit him with the kashira to the face.
Many variations of this technique exist according to the direction of one's block.

Moreover, it is also possible to start directly with a halfswording stance in order to be faster, as shown by original scrolls:

A detail from an original scroll of the Yagyu Shingan Ryū.

Again, it is worth saying that more technique exist as well, but the same rule above is still valid unfortunately.
To give you a better overview, here is one detail of the original technique:

When it comes to dagger, the situation is more clear and simple; although techniques existed as well, it is worth saying that the true field of the dagger in the armored context is to get very close and exploit the gaps of the armor, in particular in the face or the groin, to obtain a quick demise of the enemy. Most of the time, a dagger would be used on the ground, when the two armored warriors are wrestling to gain an advantage and there isn't a lot of space for complex technique.
Moreover, among dagger's design, there are some Japanese ones that are specifically made to defeat mail armor, the yoroidoshi (- armor piercer, in which armor here means mail since it's not possible to stab through lamellar or plate) and were very popular in the 16th century.
So despite there would be a lot to write, it is quite possible that a dagger's stab ended most of the fight between heavily armored samurai in a very simple and direct way.
In fact, it is worth to assume that most of the fights that involved hooking the enemy or wrestling him to the ground ended in a situation in which one of the two unsheathed his dagger to give the final blow, rather than maneuver his spears.
Daggers are faster and precise especially when the situation is very close quarter.

A good example of a "osoraku" tantō (おそらく短刀), one of the style optimized for this kind of task, born in the 16th century. Other similar ones are moroha zukuri tantō, ken tantō, yari tantō, shobu zukuri tanto and so on.  Similar if not identical designs are also found in wakizashi swords.

Final thoughts and conclusion

While most of what its written here still apply in a warfare situation, it is worth considering some important facts.
First of all, as I've said above, armored skirmishes on foot were likely ended with a dagger hit into a vital spots once the enemy was subjugated, and although the techniques described are worked well, the best solution in the heat of the battle was to keep your enemy at bay with a spear, and aim for a precise hit into his face or armpit and groin if exposed.
Another ideal solution was to close the distance as fast as possible, and once the spearhead was behind, engage with a dagger.
This is exactly what happens most of the time in the Japan armored battle league (ガチ甲冑合戦) in which fighters are supposed to engage into combat with spears, swords and daggers and are required to hit vital spots usually covered with flexible armor.Although there are some problems and flaws in my opinion in their recreation (for budget sake's, armors and weapons are made of soft materials; while this limits injuries, it also remove any substantial percussive force to the spears, and although they are occasionally used to bash the enemy into submission, the whole shaft is very flexible and there is no real perceived threat in the spear's hits), I still value a lot their experience due to the realistic approach, and it's very common for them to drop the spear and engage into jiujitsu with daggers. This was also true, for example, into European armored combat.
Another point is that warfare and battle are made of multiple men engaging into combat, and victory is not obtained by casualties but by routing the enemy army. This should be kept in mind, since in this context, it was totally possible that while one men hooked the enemy, a nearby allied soldier might finished him with a thrust. Teamwork was the main why to fight, even in Japan.
Push of pikes, volleys of arrows and bullets, tight skirmishes were the bread and butter of those warriors, and within these scenario, there was little space for techniques and wrestling to the ground.
Armored duels that fits in this context were rare.
Not to mention that not everyone in the field had such protective gears, and the majority of soldiers would have fought differently.
Moreover, the men that could afford such armors were usually deployed in the cavalry, and while they could fight either as shock cavalry or as mounted infantry, they were usually specialized in routing, chasing and flanking the enemy formations, although occasionally they also fought against similar equipped warriors as well.

So with all these things in mind, it is important to highlight that the things I wrote here, while still viable, are confined into a niche in the context of the historical battles and warfare of Japan.

Thank you for reading all of this; I hope that it was entertaining and informative! It took a lot of research and time but it was extremely fun to write, and I hope it's the same to read!
Please for any questions don't hesitate to ask in the comment and feel free to share it.

Gunbai