Somebody recently told me that chainmail was the most effective armor against arrows, not plate as was often said, which is amusing since the "common wisdom" always held that chain was worst (the point of the arrow finding the "holes" in the mesh, supposedly." That someone said it was because the chain has a bit of "give"' in it and catches the arrowhead like a net- which is exactly how Kevlar weave stops modern bullets. Sounds like another example of historians who know jack about ballistics or the concept of modern testing making empirical statements again. -.-
In terms of pure protective capabilities, mail really wasn't that far behind plate.
The absolute #1 advantage of plate armor is maneuverability. A mail hauberk has every single ounce of weight hanging from your shoulders. Plus, to get decent protection against blunt trauma you needed about 4" of padding, minimum. So mail was incredibly fatiguing and hot to fight in.
Plate, in contrast, spreads the weight out over the body (and a full set of later plate armor weighed about the same as a mail hauberk, about 60 pounds), and doesn't need hot, insulating padding. Warriors in plate were maneuverable enough that King Henry III would do somersaults and cartwheels in full armor, to entertain guests.
I haven't looked at armor that closely, but 40D, anyway, had the exact opposite. Of course, it could very well be that dwarven plate is overengineered and tremendously thick compared to human stuff.
Anyway, though, chainmail was pretty much proof against arrows. But then, so was plate. You may've seen recent "research" on whether bodkin points could pierce plate, but that study was very unrealistic. The guy that did it even acknowledged that the carbon content (and thus hardness) of the bodkin points used were far in excess of any known historical example. That's led a lot of people to the wrong conclusion about arrows vs. armor. Historical examples of bodkin points are made out of metal that's softer than what plate armor was made from, so their chances of punching through a plate, even on a perfectly aligned close range shot, was slim to none.
Bodkins really weren't effective against mail armor, either. The logic goes that maybe a bodkin point could slip into a ring and force it apart, but at realistic combat distances, the arrow doesn't have anywhere near enough weight or velocity to do that. It's far more likely that bodkins were simply a point that was very easy to mass-produce, a good design to find small gaps in armor (especially around the visor), and would be much more effective against boiled leather armor, like a fellow peasant-soldier might wear, at long range. Historically speaking, though, the majority of armored knights who were killed by arrows, were shot in the face while their visor was up.
Some people also like to cite the battles of Agincourt and Crecy when discussing the effectiveness of arrows vs. plate, but French tactics in both cases were so utterly moronic, that it was physically impossible for the English to have lost either time. The worst the English could've done would have been a tie, and that only if they had committed mass suicide! Even a retreat would have resulted in piles of dead French knights at the bottom of a bog.
No, the English were victorious in those battles not due to any real advantages of the longbow, but because the French were idiots (they also disobeyed orders from their king, saying to hold back, both times). They thought, first of all, that a knight on foot would be just as effective as a knight on horseback (big surprise, they weren't). And second, they thought that a 3 foot deep muddy bog was perfectly safe for a guy with 60 pounds of steel to wade through (how could that ever go wrong?). And third, they thought that no adjustment of tactics whatsoever was necessary to compensate for the lack of horses or bad terrain, like they insisted on sending their crossbowmen out without whatchamacallits (those portable shield things that you can hide behind while reloading).
The majority of actual "kills" (as opposed to technical suicides) of French knights, in both battles, were actually inflicted by billhooks and other hand weapons, on Frenchmen who had been "lucky" enough to fall on their backs in a shallow spot, but who still couldn't get up because of the mud. Arrows were mainly useful for taking out French crossbowmen, and that because they had been sent out without their shields.
Anyway, though, I guess it is technically true that mail armor stops arrows the same way that kevlar stops bullets. But that has little to do with anything, given that plate also made the wearer virtually immune to arrows, as long as they kept their visor down (but it's impossible to shout orders without raising it).
The inaccuracies of "research" on piercing capabilities of bodkin points is mostly acquainted to our inability to replicate the impurities of the armor of the period, but of course when compared to modern materials the bodkin pierces chain, and punches holes in plate. But the supposed usage of the bodkin point is a "armor piercing" replacement for the broadhead, their unique shape of a thin square-pyramid gave them an advantage compared to the large triangular tip of the broadhead. It served the post better than the broadhead because of the ease of manufacture, and the concentration of force on a small point could cause a much more serious wound on a target causing more than just laceration, or gashing. Although it still was not a very good armor piercer, working best on lightly armored people.
The longbows advantage was that it did not require the downward inertia of the falling arrow (like a normal bow)to achieve the maximum power, but rather because the unique make and composition of the yew longbow, it allowed the archer to fire directly at his target with full force giving it a great advantage. The draw weight of the bow was also insane (100lbs-185lbs) compared to the modern 60lbs standard (which would likely send the arrow quite far through an unarmored person), these factors combines with the range of the bow (the standard practice range was 220yds by order of Henry III) gave English bowmen the advantage over the standard archer.
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I'm happy i found this mod before i actually starting getting into large fights. Too bad you couldn't have multiple arrow types with a single bow, It'd be awesome if you use special arrows without making a custom bow just to use that ammunition.