A hauberk or byrnie is a mail shirt. The term is usually used to describe a shirt reaching at least to mid-thigh and including sleeves.[1] A haubergeon ("little hauberk") refers to a smaller mail shirt,[2] that was sometimes sleeveless,[3] but the terms are occasionally used interchangeably.[3] Mail armor, likely invented by the Celts, became widely adopted for its flexibility and spread throughout Europe and Asia, becoming a staple in Roman legions and medieval warfare. By the 11th century, the hauberk evolved into a knee-length, sleeved mail shirt, as depicted in the Bayeux Tapestry and it remained in use in Europe until the Renaissance despite the rise of plate armor.