phalanx, ancient Greek formation of infantry. The soldiers were arrayed in rows (8 or 16), with arms at the ready, making a solid block that could sweep bristling through the more dispersed ranks of the enemy. Originally employed by the Spartans, it was developed by Epaminondas of Thebes (d. 362 B.C.). Use of the phalanx reached its apex when Philip II and Alexander the Great used the great Macedonian phalanx (16 deep and armed with the sarissa, a spear c.13 ft/4 m long) to conquer all Greece and the Middle East. Later, the Macedonian phalanx deteriorated and had few Macedonians in it; it was defeated in several battles with the Romans who conquered (168 B.C.) the Macedonians at Pydna. Thereafter the phalanx was obsolete. Because it lacked tactical flexilibity, the phalanx was a better defensive than offensive formation.

Tactical formation consisting of a block of heavily armed infantry standing shoulder to shoulder in files several ranks deep. First used by the Sumerians and fully developed by the ancient Greeks, it is viewed today as the beginning of European military development. The Greek city-states adopted a phalanx eight men deep during the 7th century BC. The spectacle of Greek hoplites marching forward in solid ranks was frightening to the enemy, but the phalanx was difficult to maneuver and easily thrown into confusion if its ranks were broken.

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