infantry, body of soldiers who fight in an army on foot and are equipped with hand-carried weapons, in contradistinction originally to cavalry and other branches of an army. Infantry has often been divided into heavy infantry, which used to wear armor and now fights with tanks, and light infantry, which used to include skirmishers, slingers, and bowmen and now includes commandos and troops with only light tanks. In ancient wars, infantry was armed with swords, spears, slings, and bows. Around 2500 B.C. the armies of the city-states of Ur and Lagash in Mesopotamia fought in formation with shield walls and protruding longspears. The Greek phalanx was the dominant infantry formation in the West from c.500 B.C. until the ascendancy of the more flexible Roman legion. In China, where the crossbow (see bow and arrow) was widely used, more flexible formations and deception were emphasized (see Sun Tzu) along with fortifications such as the Great Wall. Infantry declined as the major fighting force in Eurasia after the 4th cent. when cavalry became dominant, but in the Americas the infantry dominated until the horse was introduced by the Spanish conquistadors. After the middle of the 14th cent., when firearms were first used, the infantry, armed with muskets and rifles, became dominant. Before the advent of automatic weapons at the end of the 19th cent., infantry fought in massed formations; in the Boer War and in World War I the mass formation gave way to trench warfare. See army; strategy and tactics; warfare.
See J. Keegan and R. Holmes, Soldiers (1980).
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