14. The Romans Did Not Hesitate to Adopt New Tactics from Their Enemies When Necessary
Roman legions originally consisted of spear-armed soldiers, who fought in dense phalanxes. They switched to a more spread-out legion with sword-wielding legionaries because of the Samnite Wars, fought from 343 to 290 BC. The Samnites inhabited the Apennine Mountains south of Rome, and in that rough terrain, the dense phalanx proved to be unwieldy. By contrast, the Samnites were armed with swords and fought in flexible formations, with smaller subunits known as maniples (“handfuls”). They ran rings around the Romans and dealt them a series of defeats that culminated in the surrender of an entire Roman army at the Caudine Forks in 321 BC. The Romans were pragmatic, and often copied from others what worked. So they abandoned the phalanx and adopted the manipular system around 315 BC, and legions were broken into heavy infantry maniples of 120 men, in three ranks of 40 men.
Until the late second century BC, Roman soldiers paid for their own equipment, and maniples were deployed in three layers, based on experience and wealth. In front of them were the velites, or skirmishers, often the youngest and nimblest. The first heavy infantry line were the hastati, armed with short swords, a squared shield, the scutum, and throwing spears, the pila. Then came the princepes, prosperous men in the prime of their lives, who could afford decent equipment. Finally came the triari, the oldest and often richest men, who could afford the best equipment. Armed with spears, they formed the last battle line. They were seldom used, because battles were usually won by the soldiers ahead of them. They were only committed if things went wrong, and “it has come to the triarii” became a common Roman phrase to mean the need to use one’s last resort.