The Macedonians (Alrexander the Great and his father, Philip) perfected the older Greek Phalanx formation in the 4th cenury BC. This fighting organization consisted of heavily armored infantry carrying a shield and a long (up to 18 feet) spear. The basic formation was 250 men wide and 16 men deep. The Macedonian innovation was to have each rank holding the spear at a different length so that when the spears were held parallel to the ground, the front of the formation was a wall of spear points. When charging at a trot, the Phalanx carried all before it, whether the foe be infantry, cavalry, or even chariots. This formation was unwieldy, and required constant practice to make it work on the battlefield. The Romans beat it by being even more flexible on the battlefield, using tactics which permitted their swordsmen to pass under the spearpoints, and maneuvering to hit the Phalanx on its vulnerable flank or rear.