The tabard, a decorated, open-sided smock, had its origins in the Holy Wars known as the Crusades. Beginning in the late eleventh century, knights from western Europe began to journey to the Middle East to try to "reclaim" the Christian Holy Lands from the Muslims who lived in present-day Israel. Dressed in heavy chain mail (flexible armor made of intertwining metal chains), and metal armor, the knights found themselves roasting under the Middle Eastern sun. Seeking to keep the sun from heating the metal, they invented a simple smock to wear over their armor. Called a surcote, this was a long rectangular piece of fabric with a hole cut in the middle for the head. It was belted about the waist. When these knights returned home, their utilitarian garments were adopted for use as everyday wear and were renamed tabards.
The tabard retained the basic form of the surcote, and it was worn on top of other clothes, but the resemblance ended there. The tabard was shorter, ending at the waist. It was often trimmed out with fur at the hem and armholes. It was often parti-colored, which meant it had sides made in fabrics of contrasting color. Finally, tabards were often decorated with a coat of arms, emblems that featured different symbols and which were claimed as a kind of family seal. A typical coat of arms might have a shield background, a family motto, and an animal, all surrounded by decorative flourishes. Tabards were typically worn for ceremonies and survived into the late Middle Ages (c. 500–c. 1500).
Bigelow, Marybelle S. Fashion in History: Apparel in the Western World. Minneapolis, MN: Burgess Publishing, 1970.
Yarwood, Doreen. The Encyclopedia of World Costume. New York: Charles Scribner's Sons, 1978.