Polybius first described the maniple in the mid-second century BC. The manipular legion was organized into four lines, starting at the front: the velites, the hastati, the principes, and the triarii. These were divided by experience, with the younger soldiers at the front lines and the older soldiers near the back.

When did Rome adopt the maniple?

Historical origin. The Manipular system was adopted at around 315 BC, during the Second Samnite War. The rugged terrain of Samnium where the war was fought highlighted the lack of manoeuvrability inherent in the phalanx formation which the Romans had inherited from the Etruscans.

What was so special about the maniple within the Roman army?

More importantly, these maniple formations allowed for a battlefield system of reserves being deployed for better tactical advantage. For example, when the front-lining hastati was drained of his strength during the heat of the battle, he could fall back upon the reserve lines of the principes.