Transformation of the Hoplite Phalanx
In the two great battles of the Peloponnesian War, at Delium and Mantinea, one sees the very beginning of the Greek infantry tactics of deep columns, reserves, integrated cavalry units, adaptation to terrain, and secondary maneuvers, which would only accelerate in the fourth century [B.C.E.] under Epaminondas and come to fruition with Philip and Alexander. Hoplite battle in the Peloponnesian War began a slow transformation, from phalanxes rather artificially deciding wars to hoplites becoming part of an integrated force of horsemen, light-armed troops, and missile troops that could win theaters of conflict on the basis of military efficacy rather than traditional protocol.
— Victor Davis Hanson, A War Like No Other, p. 141