Maniple (military unit)
In 390 BC, the Gauls sacked Rome after defeating the Roman Republican army at Allia River.
One of the weaknesses of the Roman army that the Gauls had exposed was the inflexibility of their Hellenic style phalanx formation that they inherited from the Etruscans. To overcome this sort of limitation, the army was split up into subsets called Maniples (it translates roughly to English as 'handfuls') which could perform actions with more independence from one another.
The army was organized into 3 lines during the Roman Republic, the hastati, the principes, and the triarii. Each of these lines was divided into maniples of 120, 120 and 60 men, respectively. Thus, the legion proper consisted of about 3,000 men.
There were also very light troops called velites. Unarmored and armed with stones or slings, they stood in front of the line to launch missiles first and screen the army's formation and size from the eyes of the enemy, but then they moved off when the battle began. The velites were not separated into maniples.
Primary sources for early Roman military organization include the writings of Polybius and Livy.
