The two most effective armies in the ancient world were the Roman army, and the Macedonian army under Alexander the Great. The Macedonian Army was based on the phalanx, where a box of men eight men deep stood with spears and shields against the foe. Though what really gave the Macedonians an edge over the Classical Greeks was their use of heavy cavaly to provide the versatile attack force. In battle the Phalanxes were used in methods similar to a shield, they protected the centre of the army and drew the enemy infantry there, the cavalry were used as the spear, who would rush in the moment a gap appeared, or at the unprotected flanks of enemy infantry. 

Philip the II is widely known to have perfected the Macedonian phalanx prior to his invasion of Greece. He removed the traditional 'hoplon' shield for a smaller-lighter shield, in addition he gave the suggestion that the phalangites should hold their 15+ foot spears with two hands. The development of the phalanx by perfecting it and adding cavalry support turned Macedon from a fragile state, into a powerful nation who would eventually rule all of Greece and the mighty Persian Empire. These troops were known to the Macedons as the 'Pezhetairoi' or foot (pez) companions (hetairoi), they were a powerful elite troop who contrasted traditional Greek armies of levies with professional troops with high levels of skill and training. Each Phalanx group would be composed of roughly 1,500 men, and be part of a larger group of 9,000 (varied) Pezhetairoi.

Pilip and later Alexander did not use the Phalanxes as their offensive arm in battle, rather using it to hold the enemy down while the hetairoi (cavalry companions) charged from the front and the rear. One famous example of this was Gaugamela in 331 BCE, where Alexander beat Darius III's army of 100,000 by pinning the infantry down at the centre, isolating and defeating the Persian Cavalry on the right, and scaring Darius himself off the field by charging straight at him.