A greave, in French also called jambeau, is a piece of armour that protects the lower leg. The main purpose of a greave was to protect the shinbone, or tibia.
Because the shinbone lies close to the skin, it's particularly vulnerable to virtually any type of attack. A successful blow to the shinbone can render the leg unusable, leaving the wearer barely able to move. Greaves were therefore an essential part of the armour.
Construction
Greaves typically consisted of a metal exterior with a soft inner lining of felt or other material. This padding was crucial, because a direct blow to metal without cushioning would transfer all the force to the shinbone, which could be very painful or even paralyzing.
Historical use
Greaves were already known until around the 9th century AD, but largely disappeared from use after that. They reappeared around the years 1230–1250, as seen in the illustration of Goliath in the Trinity College Apocalypse manuscript (ca. 1230).
The fact that there is little further evidence of greaves from this time suggests they were not yet in common use.
The greaves from this early period were mostly schynbalds, that is, plates that protected only the shinbone and did not fully enclose the lower leg.
Illustrations of closed greaves, which covered the entire lower leg, appear only around 1290 and became popular in the 1320s. Closed greaves consisted of two plates connected on the outside by hinges and fastened on the inside with belts and buckles, thus protecting the lower leg completely.
