the first cohort being of double strength (five double-strength centuries with 160 men each). By the fourth century AD, the legion was a much smaller unit of about 1,000 to 1,500 men, and there were more of them. This had come about as the large formation legion and auxiliary unit, 10,000 men, was broken down into smaller units – originally temporary detachments – to cover more territory. In the fourth century AD, East Roman border guard legions (limitanei) may have become even smaller. History Roman Kingdom (to c. 500 BC) In the period before the raising of the legio and the early years of the Roman Kingdom and the Roman Republic, forces are described as being organised into centuriae of roughly one hundred men. These centuries were grouped together as required and answered to the leader who had hired or raised them. Such independent organisation persisted until the 2nd century BC amongst light infantry and cavalry, but was discarded completely in later periods with the supporting role taken instead by allied troops. The roles of century leader (later formalised as a centurion), second in command and standard bearer are referenced in this early period. Rome's early period is undocumented and shrouded in myths, but those myths tell that during the rule of Servius Tullius, the census (from Latin: censeō – accounting of the people) was introduced. With this all Roman able-bodied, property-owning male citizens were divided into five classes for military service based on their wealth and then organised into centuries as sub-units of the greater Roman army or legio (multitude). Joining the army was both a duty and a distinguishing mark of Roman citizenship; during the entire pre-Marian period the wealthiest land owners performed the most years of military service. These individuals would have had the most to lose should the state have fallen. Roman Republic (509–107 BC) At some point after the overthrow of the Roman monarchy the legio was subdivided into two separate legions, each one ascribed to one of the two consuls. In the first years of the Republic, when warfare was mostly concentrated on raiding, it is uncertain if the full manpower of the legions was summoned at any one time. In 494 BC, when three foreign threats emerged, the dictator Manius Valerius Maximus raised ten legions which Livy says was a greater number than had been raised previously at any one time. Also, some