The Macedonian phalanx is an infantry formation developed by Philip II and used by his son Alexander the Great to conquer the Persian Empire and other armies. Phalanxes remained dominant on battlefields throughout the Hellenistic period, although wars had developed into more protracted operations generally involving sieges and naval combat as much as field battles, until they were finally displaced by the Roman legions.
Read more about Macedonian Phalanx: Development, Equipment, Formation, Drawbacks, Advantage, Attempts For Revival in The Roman Period