Cavalry

n. troops that serve on horseback, mobile military unit on horseback or motor vehicles

Cavalry (from French cavalerie) were soldiers or warriors who fought mounted on horseback in combat. The designation was not usually extended to any military force that used other animals, such as camels or mules. Infantry who moved on horseback but dismounted to fight on foot were in the seventeenth and early eighteenth centuries known as  dragoons, a class of mounted troops which later evolved into cavalry proper while retaining their historic title. From earliest times cavalry had the advantage of improved mobility, an "instrument which multiplied the fighting value of even the smallest forces, allowing them to outflank and avoid, to surprise and overpower, to retreat and escape according to the requirements of the moment." A man fighting from horseback also had the advantages of greater height, speed, and inertial mass over an opponent on foot.
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Noun
1. troops trained to fight on horseback; "500 horse led the attack"
(synonym) horse cavalry, horse
(hypernym) military personnel, soldiery, troops
(member-meronym) cavalryman, trooper
(classification) military, armed forces, armed services, military machine, war machine
2. a highly mobile army unit
(hypernym) army unit
(hyponym) squadron
(member-meronym) troop
(classification) military, armed forces, armed services, military machine, war machine

(n.)
That part of military force which serves on horseback.
  

A mounted man, a 'chevalier ', a horseman. The chevalier is the root of the word 'chivalry '. During the Middle Ages it was a commonly belief military theorem that no force on the battlefield could stand up to a charge by heavy cavalry. This belief was reinforced by various defeats of infantry by cavalry, such as at Hastings . During the 14th century a more balanced approach to warfare was experimented with by the Scots and English, especially by Edward III and Robert the Bruce. Edward made excellent use of artillery in the form of archers , infantry in the form of dismounted knights supported by a flanking unit of cavalry.