A greave is a piece of armour

Armour

Armour or armor is protective covering used to prevent damage from being inflicted to an object, individual or a vehicle through use of direct contact weapons or projectiles, usually during combat, or from damage caused by a potentially dangerous environment or action...

 that protects the leg

Human leg

The human leg is the entire lower extremity or limb of the human body, including the foot, thigh and even the hip or gluteal region; however, the precise definition in human anatomy refers only to the section of the lower limb extending from the knee to the ankle.Legs are used for standing,...

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Description

Often in matched pairs (a pair of greaves), greaves may be constructed of materials ranging from padded cloth to steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 plate. Some designs protect only the lower leg (a half-greave) or extend upwards to protect the thigh

Thigh

In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...

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Greaves are most commonly found in the armor of heavy infantry

Infantry

Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...

, usually from ancient times. Greek hoplites

Hoplite

A hoplite was a citizen-soldier of the Ancient Greek city-states. Hoplites were primarily armed as spearmen and fought in a phalanx formation. The word "hoplite" derives from "hoplon" , the type of the shield used by the soldiers, although, as a word, "hopla" could also denote weapons held or even...

 wore a bronze greave on each leg. Triarii

Triarii

Triarii were one of the elements of the early Roman military Manipular legions of the early Roman Republic . They were the oldest and among the wealthiest men in the army, and could afford good quality equipment. They wore heavy metal armour and carried large shields, their usual position being...

, the better equipped soldiers of the pre-Marian Roman Republic

Roman Republic

The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...

, wore greaves on both shins reminiscent of the Ancient Greeks. Principes

Principes

Principes were spearmen, and later swordsmen, in the armies of the early Roman Republic. They were men in the prime of their lives who were fairly wealthy, and could afford decent equipment. They were the heavier infantry of the legion who carried large shields and wore good quality armour. Their...

and hastati

Hastati

Hastatii were a class of infantry in the armies of the early Roman Republic who originally fought as spearmen, and later as swordsmen. They were originally some of the poorest men in the legion, and could afford only modest equipment — light armour and a large shield, in their service as the...

often only wore one greave (on their left leg) or none. The Roman Centurion

Centurion

A centurion was a professional officer of the Roman army .Centurion may also refer to:-Military:* Centurion tank, British battle tank* HMS Centurion, name of several ships and a shore base of the British Royal Navy...

s wore altered greaves from the standard Roman uniform. Later Imperial legionnaires did not wear greaves, except for the centurions who retained them.

In the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

, greaves eventually developed to protect the back of the legs as well and these were called full greaves (the style which only covered the front became known as half-greaves or demi-greaves).

Greaves are also mentioned in the Old Testament

Old Testament

The Old Testament, of which Christians hold different views, is a Christian term for the religious writings of ancient Israel held sacred and inspired by Christians which overlaps with the 24-book canon of the Masoretic Text of Judaism...

 identifying an article of armor worn by the giant Goliath (1 Sam 17:6)http://www.biblegateway.com/passage/?search=1%20samuel%2017:6;&version=9; as he fought David, the young Hebrew shepherd.

The Japanese (samurai

Samurai

is the term for the military nobility of pre-industrial Japan. According to translator William Scott Wilson: "In Chinese, the character 侍 was originally a verb meaning to wait upon or accompany a person in the upper ranks of society, and this is also true of the original term in Japanese, saburau...

) form of greaves are called suneate

Suneate

Suneate are a type of armored shin protection worn by the samurai class during the feudal era of Japan. Suneate first started being used in the 12th century.-Description:...

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