Mail or chain mail is a type of armour consisting of small metal rings linked together in a pattern to form a mesh.
The word chainmail is of relatively recent coinage, having been in use only since the 1700s; prior to this it was referred to simply as mail.
The word itself refers to the armour material, not the garment made from it. A shirt made from mail is a hauberk if knee-length, haubergeon if mid-thigh length, and byrnie if waist-length. Mail leggings are called chausses, mail hoods coif and mail mittens mitons. A mail collar hanging from a helmet is camail or aventail. A mail collar worn strapped around the neck was called a pixane or standard.
Mail is now often used for decorative use and in jewellery.
The use of mail was prominent throughout the Dark Ages, High Middle Ages and Renaissance, and reached its apex in Europe, in terms of coverage, during the 13th century, when mail covered the whole body.
The earliest finds of mail are from the 3rd century BC from Horny Jatov, Slovakia and a Celtic chieftain's burial located in Ciumeşti, Romania. It is believed that the Roman Republic first came into contact with mail fighting the Gauls in Cisalpine Gaul, now Northern Italy. The Roman army adopted the technology for their troops in the form of the lorica hamata which was used as a primary form of armour through the Imperial period.
By the 14th century, plate armour was commonly used to supplement mail. Eventually mail was supplanted by plate for the most part. However, mail was still widely used by many soldiers as well as brigandines and padded jacks. These three types of armour made up the bulk of the equipment used by soldiers with mail being the most expensive. It was quite often more expensive than plate armour. A mail shirt interwoven between two layers of fabric is called jazzeraint, and can be worn as protective clothing.
Extant mail is common, but it is not proportionately represented in museum collections.
The Japanese used mail (kusari) in a limited fashion in armour beginning during the Nambokucho period (1336–1392). Two primary weave methods were used: a square 4-in-1 pattern (so gusari) and a hexagonal 6-in-1 pattern (hana gusari). Kusari was typically made with rings that were much smaller than their European counterparts, and on a much smaller scale – small sections were used to link together plates and to drape over vulnerable areas such as the underarm. The rings were not welded nor riveted shut, though some pieces were constructed of rings that consisted of two or more turns, similar to the modern split ring commonly used on keychains. The rings were lacquered to prevent rusting, and was always stitched onto a backing of cloth or leather. The kusari was sometimes concealed entirely between layers of cloth or leather. Japanese mail was also produced as a standalone defense, and kusari katabira or mail coats were very common in the Edo period. Kusari hoods, gloves, vests, shin and thigh guards, and other protective clothing were produced (even kusari tabi socks). "Entire suits of mail (kusari gusoku) were worn on occasions, sometimes under the ordinary clothing"  Mail construction is mentioned in the Quran as knowledge that God gave to David.
21:80 It was We Who taught him the making of coats of mail for your benefit, to guard you from each other's violence: will ye then be grateful? (Yusuf Ali's translation).
Mail armour provided an effective defence against slashing blows by an edged weapon and penetration by thrusting and piercing weapons; in fact The Royal Armoury at Leeds concluded that "...it is almost impossible to penetrate using any conventional medieval weapon..." Generally speaking, mail's resistance to weapons is determined by four factors: linkage type (riveted, butted, or welded), material used (iron versus bronze or steel), Weave density (a tighter weave needs a thinner weapon to surpass), and ring thickness (generally ranging from 16 to 12 gauge in most examples). Mail, if a warrior could afford it, could provide a significant advantage to a warrior when combined with competent fighting techniques. However, a good sword blow arriving in exactly perpendicular angle to surface could cut through the links; when the mail was not riveted a well placed thrust from a spear or thin sword could penetrate, and a poleaxe or halberd blow could break through the armour. Special arrows, known as bodkins, were later made that were able to penetrate light mail through the loops of the chain. Some evidence indicates that during armored combat the intention was to actually get around the armor rather than through it- according to a study of skeletons found in Visby, Sweden, a majority of the skeletons showed wounds on less well protected legs.
The flexibility of mail meant that a blow would often injure the wearer, potentially causing serious bruising or fractures, and it was a poor defence against head trauma. Mail-clad warriors typically wore separate rigid, helms over their mail coifs for head protection. Likewise, blunt weapons such as maces and warhammers could harm the wearer by their impact without penetrating the armour; usually a soft armour, such as gambeson, was worn under the hauberk. Mail, however, had importance in that it reduced the risk of cuts and infection that could often be life threatening to a soldier.
The word chainmail is a pleonasm and a neologism: in the Middle Ages and Renaissance, "mail", "mayle" or chain was the English name for it, maille was the common French name, and it was called maliën in Flemish and Dutch. This—and the alternative spellings "maile" and "maille"—derive through the Italian maglia, from the Latin macula, meaning "mesh of a net". The Spanish corresponding word is malla and in Portuguese it is malha. The Welsh term lluric derives from the Latin lorica.
Many modern American armourers prefer the French spelling "maille" in order to avoid confusion with the term chain letter for "chainmail" or postal delivery for "mail".
Several patterns of linking the rings together have been known since ancient times, with the most common being the 4-to-1 pattern (where each ring is linked with four others). In Europe, the 4-to-1 pattern was completely dominant. Mail was also common in East Asia, primarily Japan, with several more patterns being utilised and an entire nomenclature developing around them.
Historically, in Europe, from the pre-Roman period on, the rings composing a piece of mail would be riveted closed to reduce the chance of the rings splitting open when subjected to a thrusting attack or a hit by an arrow.
Up until the 14th century European mail was made of alternating rows of both riveted rings and solid rings. After that it was almost all made from riveted rings only. Both would have been made using wrought iron. Some later pieces were made of wrought steel with an appreciable carbon content that allowed the piece to be heat treated. Wire for the riveted rings was formed by either of two methods. One was to hammer out wrought iron into plates and cut or slit the plates. These thin pieces were then pulled through a draw-plate repeatedly until the desired diameter was achieved. Waterwheel powered drawing mills are pictured in several period manuscripts. Another method was to simply forge down an iron billet into a rod and then proceed to draw it out into wire. The solid links would have been made by punching from a sheet. Forge welding was also used to create solid links, but the only known example from Europe is that of the 7th century Coppergate mail drape. Outside of Europe this practice was more common such as "theta" links from India.
Mail is used as protective clothing for butchers against meat-packing equipment. Workers may wear up to 8 lb (4 kg) of mail under their white coats. Butchers also commonly wear a single mail glove to protect themselves from self-inflicted injury while cutting meat.
Woodcarvers sometimes use similar mail gloves to protect their hands from cuts and punctures.
Scuba divers use mail to protect them from sharkbite, as do animal control officers for protection against the animals they handle. Shark expert and underwater filmmaker Valerie Taylor was among the first to develop and test the mail suit in 1979 while diving with sharks. The British police use mail gloves for dealing with knife-armed aggressors.
During World War I, mail was evaluated as a material for bullet proof vests, but results were unsatisfactory as the rings would fragment and further aggravate the damage. A mail fringe, designed by Captain Cruise of the British Infantry, was added to helmets to protect the face but this proved unpopular with soldiers, in spite of being proven to defend against a three-ounce (100 g) shrapnel round fired at a distance of one hundred yards (90 m).
Stab Proof Vests
After an intensive period of study and analysis of stab vests starting in the 1980s revealed that vests capable of providing ballistic protection were insufficient to protect against "ice-picks" or knife thrusts. The highest threat-level of modern stab-proof vests are now being made which incorporate mail armour.
There is anecdotal evidence to suggest that mail is a viable alternative to heavy leather for protecting motorcyclists from injury should they be thrown from their motorcycles.
Many historical reenactment groups, especially those whose focus is Antiquity or the Middle Ages, commonly use mail both as practical armour and for costuming. Mail is especially popular amongst those groups which use steel weapons. A fighter wearing hauberk and chausses can run, lie, stand up, jump, do somersaults (or even cartwheels), and even swim wearing full armour, depending on the fitness of the wearer. A modern hauberk made from 1.5 mm diameter wire with 10 mm inner diameter rings weighs roughly 10 kg and contains 15,000–45,000 rings. Mail can be used under everyday clothes and many reenactors wear a hauberk under their regular clothes to accustom themselves to it.
One of the two real drawbacks of mail is the uneven weight distribution; the stress falls mainly on shoulders. Weight can be better distributed by wearing a belt over the mail, which provides another point of support.
A reenactment of a long-distance march conforming to service conditions in the Imperial Western Roman army has recently revealed that mail which is worn daily is effectively rustproof and self-polishing; the motion of the rings against each other keeps them scoured.
Mail remained in use as a decorative and possibly high-status symbol with military overtones long after its practical usefulness had passed. It was frequently used for the epaulettes of military uniforms. It is still used in this form by the British Territorial Army, and the Royal Canadian Armour Corps of the Canadian Army.
Mail also has applications in sculpture and jewelry, especially when made out of precious metals or colorful anodized metals. Recent trends in mail artwork include headdresses, Christmas ornaments, chess sets, and all manner of jewelry. For these non-traditional applications, hundreds of new weaves or patterns have been invented.
In some films, knitted string spray-painted with a metallic paint is used instead of actual mail in order to cut down on cost (a notable example being Monty Python and the Holy Grail, which was filmed on a very small budget). Films more dedicated to costume accuracy often use ABS plastic rings, for the lower cost and weight. Thousands of such ABS mail coats were made for the Lord of the Rings film trilogy, in addition to many metal coats. The metal coats are used rarely because of their weight, except in close-up filming where the appearance of ABS rings is clearly distinguishable.