Tactics
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).
Perhaps the most prominent example of the phalanx's evolution was the oblique advance, made famous in the Battle of Leuctra. There, the Theban general Epaminondas thinned out the right flank and centre of his phalanx, and deepened his left flank to an unheard-of 50 men deep. In doing so, Epaminondas reversed the convention by which the right flank of the phalanx was strongest. This allowed the Thebans to assault in strength the elite Spartan troops on the right flank of the opposing phalanx. Meanwhile, the centre and right flank of the Theban line were echeloned back, from the opposing phalanx, keeping the weakened parts of the formation from being engaged. Once the Spartan right had been routed by the Theban left, the remainder of the Spartan line also broke. Thus by localising the attacking power of the hoplites, Epaminondas was able to defeat an enemy previously thought invincible.
Philip II of Macedon spent several years in Thebes as a hostage, and paid attention to Epaminondas' innovations. Upon return to his homeland, he raised a revolutionary new infantry force, which was to change the face of the Greek world. Phillip's phalangites were the first force of professional soldiers seen in Ancient Greece apart from Sparta. They were armed with longer spears and were drilled more thoroughly in more evolved, complicated tactics and manoeuvres. More importantly, though, Phillip's phalanx was part of a multi-faceted, combined force that included a variety of skirmishers and cavalry, most notably the famous Companion cavalry. The Macedonian phalanx now was used to pin the centre of the enemy line, while cavalry and more mobile infantry struck at the foe's flanks. Its supremacy over the more static armies fielded by the Greek city-states was shown at the Battle of Chaeronea, where Philip II's army crushed the allied Theban and Athenian phalanxes.
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