Augustus and the Roman Military

• Augustus reduced the number of legions to a sustainable level, settling veterans in 28 new Roman colonies
• The number of legions remained close to that level throughout the Principate (varying between 25 and 33 in number)
• The new term of service for legionary recruits was deeply unpopular with the troops, and was prohibited from marrying
• Augustus offered land instead of cash in Roman colonies established in the newly annexed frontier provinces
• The imperial authorities could not compromise on this issue, as the planting of colonies of Roman veterans was a crucial mechanism for controlling and Romanising a new province
• Legionary recruitment was localised in the early Empire, with over half of recruits not Italian-born.
• Augustus modified the command structure of the legion to reflect its new permanent, professional nature.
• In the late Republic, military tribunes were eclipsed by higher-ranking officers of senatorial rank called legati.
• A proconsul (Republican governor) might ask the senate to appoint a number of legati to serve under him.
• These commanded detachments of one or more legions at the governor's behest and played a critical role in the conquest of Gaul.
• Augustus appointed a legatus to command each legion with a term of office of several years.
• The ranking senatorial military tribune (tribunus militum laticlavius) was designated deputy commander, while the remaining five equestrian tribunes served as the legatus' staff officers.
• In addition, Augustus established a new post of praefectus castrorum (literally "prefect of the camp"), to be filled by a Roman knight (often an outgoing centurio primus pilus, a legion's chief centurion, who was usually elevated to equestrian rank on completion of his single-year term of office).
• The prefect's primary role was as the legion's quartermaster, in charge of legionary camps and supplies.
• The auxilia numbered around 250 regiments by the end of the 1st century AD.
• Each regiment consisted of around 120 infantrymen and 80 cavalrymen.
• The auxilia were ethnically based and recruited from the same regions as the legionaries.
• The auxilia were designed to complement the legions, and their role was unchanged until after the Social War.

Test your knowledge of Augustus's reforms and the military structure of the Roman Empire during the Principate. Explore the changes in legionary recruitment, command structure, and the role of auxiliary units.