Armor: How effective was Chainmail

[Condottiero Magno]

There are, however, a number of high Medieval accounts of couched lances penetrating mail. Also, as has been already mentioned, mail often merely converted a piercing or cutting blow into a blunt-trauma injury, which could be incapacitating or mortal.

We've done this argument before in the Leather vs. Metal debate. Nothing short of a Couched lance can penetrate accurate mail, not even arrows. The couched lance was introduced by the Turks in the 9th century and needed Stirrups to be used with effect, so the Romans didn't have to worry about that.

Scorpiones can punch right through mail, I've seen video of a bolt going through the shield, armor, out the back, and into another guy's shield.

The couched lance wasn't introduced by the Turks and had been in use before the introduction of stirrups. Mail could be penetrated by piercing or cutting, depending on the situation, and if its wearer was so invulnerable, especially against most projectiles, why was it gradually replaced by pieces of plate, such as brigadine, similar to a variant of lamellar armor, and relegated to protecting armpits?

Lamellar was for the most part munitions armor. The armpits usually were considered important to protect because A. The Romans didn't use sleeves until the 4th century and B. because the blunt force trauma of a hit there would break ribs and possibly puncture the spleen or heart if a rib broke in the right manner.

Munitions armor is simply stockpiled mass produced armor, with any adjustments made later by the recipient, and it doesn't necessarily mean it's of lesser quality, though nothing beats something that's customized for the wearer - please don't throw it around like a pejorative. Mail was also for the most part munitions armor, with places devoted to manufacturing coil, another for making rings and a third for assembling it.

A and B doesn't address what I've said about the relegation of mail to areas that required protection and flexibility. As early as the 13th Century, parts of the body that was previously covered in mail, was supplemented or replaced by plate, with some influence from the East - 13th Century shoulder protection looks similar to that worn by Roman Kataphractoi, at least from 100/200 years ago.

Principiate and earlier era Roman troops didn't need arm protection, though the tech was available even earlier, looking at Archaic Age Hoplites.