Coif was a specific type of the chainmail armour that was used in medieval warfare. It referred to the piece of chainmail that was worn by a knight on his head. Like other uses of chainmail, the coif was meant to guard the head, neck and the shoulders from any direct wounds or piercings.
However, used on its own, the coif was not a sufficient form of defence in a battle and knights often used it in conjunction with a helmet which they then wore over it. The helmet warded off the blows and the coif helped the wearer against any weapons that may pierce through the openings in the helmet.
Chainmail came to be used as an important part of body armour in medieval warfare. A coif was a part of the regular chainmail which fell over the upper part of the knight’s body in order to protect him against any piercings. During this early period, coif was typically knitted together with the rest of the body of chainmail and formed a part of it.
By the middle of the 13th century, the coif was no longer used as a part of the chainmail shirt. It rather became an integral part of the head armour. While the protection offered by coif was augmented with a helmet such as a bascinet, later the coif and the helmet became united. In this form, the coif was directly attached to the helmet and shielded the wearer along with the visor.
During the medieval ages, cures for blows from blunt weapons were available and were quite effective. However, if a wound was inflicted through piercing and got infected, it usually proved fatal given the lack of medicine to treat it. The coif was useful in that it guarded the wearer’s head against any possible piercings.
When used in conjunction with a helmet, it became effective not just against piercings but also against any blunt blows. Due to the flexible nature of the chainmail, the coif easily fell down across the neck and shoulders of the wearer and shielded them effectively against any wounds.
Chainmail was typically worn because the medieval knights believed they could take the blunt wound but needed to guard against piercings. The problem with coif was that since it was worn on the head, a blunt blow to the head could cause a lot of damage. Unlike a blunt blow on the arm or the chest which could leave a repairable fracture, a similar blow to the head could prove fatal to the knight.
So a coif alone provided little in the way of protection against blunt blows. This is why it often had to be used together with a helmet such as a bascinet. It was, however, a more effective piece of armour in guarding the shoulders which it also covered. Later when it became a regular part of the helmet, it could often weigh down the heavy helmet and make mobility a problem for the wearer.