A single medieval chainmail shirt could contain over 30,000 hand-linked iron rings.

Medieval chainmail, or maille, was the primary form of metallic defense in Europe from the 3rd century BC until the 14th century AD. A standard knee-length hauberk required enormous labor, often taking a skilled armorer several months to complete. Each of the 30,000 to 50,000 rings had to be individually formed from iron wire, cut to length, and then closed using various techniques.The most common method during the High Middle Ages was riveting. Armorers would overlap the ends of a ring, punch a hole through them, and insert a tiny iron pin to lock the link permanently. This prevented the rings from pulling apart when struck by a weapon. Research by the Royal Armouries in Leeds demonstrates that while mail was nearly impervious to slashing attacks, it could be pierced by narrow bodkin arrowheads or heavy lance thrusts.To compensate for mail's inherent flexibility, soldiers wore a gambeson—a quilted garment stuffed with linen or wool. This padding was essential for dispersing the kinetic energy of impacts from maces or war hammers. Without the gambeson, a strike to the mail would not break the metal, but the force would still shatter the bones underneath. Studies of 14th-century remains from the Battle of Wisby confirm that mail provided high survival rates against standard infantry weapons when paired with proper under-padding.