Macedonian phalanx

The Macedonian phalanx is an infantry formation developed by Philip II and
used by his son Alexander the Great to conquer the Persian empire. Phalanxes
remained dominant on battlefields throughout the Hellenistic period,
although wars had evolved into more protracted operations generally
involving sieges and naval combat as much as field battles, until they were
finally displaced by the Roman legions.

Philip II spent much of his youth as a hostage at Thebes, where he studied
under the renowned general Epaminondas, whose reforms were the basis for the
phalanx. Phalangites were professional soldiers, and were among the first
troops ever to be drilled, thereby allowing them to execute complex
maneuvers well beyond the reach of most other armies. They fought packed in
a close rectangular formation, typically eight men deep, with a leader at
the head of each column and a secondary leader in the middle, so that the
back rows could move off to the sides if more frontage was needed. Unlike
earlier hoplites, phalangites were unarmored except possibly those of the
first row, and carried only tiny shields. No enemies were expected to get
close enough for them to need any.

Each phalangite carried as his primary weapon a sarissa, a double-pointed
pike over four metres in length. These were carried in two pieces, slid
together just before battle, and had to be wielded with two hands. At close
range such large weapons were useless, but an intact phalanx could easily
keep its enemies at a distance; the weapons of the first five rows of men
all projected beyond the front of the formation, so that there were more
spearpoints than available targets at any given time. The secondary weapon,
more or less an afterthought, was a small dagger.

Neither Philip nor Alexander actually used the phalanx as their arm of
choice, but instead used it to hold the enemy in place while their light
cavalry broke through their ranks. The Macedonian cavalry fought in wedge
formation and was stationed on the far right; after these broke through the
enemy lines they were followed by the hyspapists, elite infantrymen who
served as the king's bodyguard, and then the phalanx proper. The left flank
was generally covered by allied cavalry supplied by the Thessalians, which
fought in rhomboid formation and served mainly in a defensive role.

Other forces - skirmishers, range troops, reserves of allied hoplites, and
artillery - were also employed. The phalanx carried with it a fairly minimal
baggage train, with only one servant for every few men. This gave it a
marching speed that contemporary armies could not hope to match - on
occasion forces surrendered to Alexander simply because they were not
expecting him to show up for several more days. Phalangites were drilled to
perform short forced marches if required.

The armies of the early hellenistic period were equipped and fought mainly
in the same style as Alexander's. Towards the end, however, there was a
general slide away from the combined arms approach back to using the phalanx
itself as the arm of decision, having it charge into the enemy lines much
like earlier hoplites had. This left the formation fairly vulnerable -
though near invincible to forwards assault, phalanxes like other infantry
formations were fairly prone to flanking, and worse still tending to break
up when advancing quickly over rough ground. So long as everyone was using
the same tactics these weaknesses were not immediately apparent, but with
the advent of the Roman legion they proved fatal in every major engagement
(the most famous being the Battle of Pydna), as the Romans were able to
advance through gaps in the line and easily defeat the phalangites once in close.