the early history of the phalanx is largely one of combat between hoplite armies from competing greek city-states. the usual result was rather identical, inflexible formations pushing against each other until one broke. the potential of the phalanx to achieve something more was demonstrated at battle of marathon (490 bc). facing the much larger army of darius i, the athenians thinned out their phalanx and consequently lengthened their front, to avoid being outflanked. however, even a reduced-depth phalanx proved unstoppable to the lightly armed persian infantry. after routing the persian wings, the hoplites on the athenian wings wheeled inwards, destroying the elite troop at the persian centre, resulting in a crushing victory for athens. throughout the greco-persian wars the hoplite phalanx was to prove superior to the persian infantry (e.g. the battles of thermopylae and plataea).