The Roman legion (, ), the largest military unit of the Roman army, comprised 5,200 infantry and 300 equites (cavalry) in the period of the Roman Republic (509 BC–27 BC) and 5,600 infantry and 200 auxilia in the period of the Roman Empire (27 BC – AD 476). Size The size of a typical legion varied throughout the history of ancient Rome, with complements ranging from 4,200 legionaries and 300 equites (drawn from the wealthier classes – in early Rome all troops provided their own equipment) in the Republican period of Rome (the infantry were split into 10 cohorts each of four maniples of 120 legionaries), to 4,800 legionaries (in 10 cohorts of 6 centuries of 80 legionaries) during Julius Caesar's age, to 5,280 men plus 120 auxiliaries in the Imperial period (split into 10 cohorts, nine of 480 men each, with the first cohort being double-strength at 960 men). It should be noted the above numbers are typical field strengths while "paper strength" was slightly higher (e.g., 600 and 1,200 respectively for Imperial cohorts). In the early Roman Kingdom the term legion may have meant the entire Roman army, but sources on this period are few and unreliable. The subsequent organisation of legions varied greatly over time but legions were typically composed of around five thousand soldiers. During much of the republican era, a legion was divided into three lines, each of ten maniples. In the late Republic and much of the imperial period (from about 100 BC), a legion was divided into ten cohorts, each of six (or five) centuries. Legions also included a small ala, or cavalry unit. By the third century AD, the legion was a much smaller unit of about 1,000 to 1,500 men, and there were more of them. In the fourth century AD, East Roman border guard legions (limitanei) may have become even smaller. In terms of organization and function, the republican era legion may have been influenced by the ancient Greek and Macedonian phalanx. Function and constitution For most of the Roman Imperial period, the legions formed the Roman army's elite heavy infantry, recruited exclusively from Roman citizens, while the remainder of the army consisted of auxiliaries, who provided additional infantry and the vast majority of the Roman cavalry. (Provincials who aspired to Roman citizenship gained it when honourably discharged from the auxiliaries.) The Roman army, for most of the Imperial period,