Philip's most important achievement was the creation of
the Macedonian army, which he led to the conquest of Greece and which his son
was to lead to the conquest of the World. Taking a hint from the tactics of
Epaminondas, Philip trained his infantry to fight by columns, but with
sufficient intervals between the files to permit quick and easy movements. Each
man bore an enormous lance, eighteen feet in length. When this heavy phalanx
was set in array, the weapons carried by the soldiers in the first five ranks
presented a bristling thicket of lance-points, which no onset, however
determined, could penetrate. The business of the phalanx was to keep the front
of the foe engaged, while horsemen rode into the enemy's flanks. This reliance
on masses of cavalry to win a victory was something new in warfare. Another
novel feature consisted in the use of engines called catapults, able to throw
darts and huge stones three hundred yards, and of battering rams with force
enough to hurl down the walls of cities. All these different arms working
together made a war machine of tremendous power—the most formidable in the
ancient world until the days of the Roman legion.
CONQUESTS OF PHILIP
Philip commanded a fine army; he ruled with absolute sway
a territory larger than any other Hellenic state; and he himself possessed a
genius for both war and diplomacy, With such advantages the Macedonian king
entered on the subjugation of disunited Greece. His first great success was won
in western Thrace. Here he founded the city of Philippi  and seized some
rich gold mines, the income from which enabled him to keep his soldiers always
under arms, to fit out a fleet, and, by means of liberal bribes, to hire a
crowd of agents in nearly every Greek city. Philip next made Macedonia a
maritime state by subduing the Greek cities on the peninsula of Chalcidice.
He also appeared in Thessaly, occupied its principal fortresses, and brought
the frontier of Macedonia as far south as the pass of Thermopylae.
 Philippi became noted afterwards as the first city in
Europe where Christianity was preached. See Acts, xvi, 9.