The size of a typical legion varied widely throughout the history of ancient Rome, with complements of 4,200 legionaries and 300 equites in the republican period of Rome, (the infantry were split into 30 maniples of 120 legionaries each), to 5,200 men plus auxiliaries in the imperial period (split into 10 cohorts, 9 of 480 men each, plus the first cohort holding 800 men).
As legions were not standing armies until the Marian reforms (c. 107 BC), and were instead created, used, and disbanded again, several hundred legions were named and numbered throughout Roman history. To date, about 50 have been identified. In the time of the Early Roman Empire, there were usually about 25-35 standing legions plus their Auxiliaries, with more raised as needed.
Because of the enormous military successes of the Roman Republic and the Roman Empire the legion has long been regarded as the prime ancient model for military efficiency and ability.
