Roman legion

A Roman legion (Latin legio, from legere "to read" in the sense of: "to select", "to choose") was an independently operating large military unit in the Roman Empire, which usually consisted of 3000 to 6000 soldiers of heavy infantry and a small detachment of legionary cavalry with about 120 men. As a factor for the success of the Roman legions, besides superior equipment and the united use in battle formations, the intensive training and discipline in battle, but also tactical flexibility are seen. It thus formed an essential factor in the expansion of the Roman Empire. To secure the world empire on three continents, about 25 to 30 legions were sufficient in the heyday of the empire in the Roman Imperial period, which could be quickly deployed via marching roads and by ship.

In the early days of Rome, legion was the name given to the entire military contingent of the city, raised and commanded by the two consuls. With the growth of the Ager Romanus and when special needs arose, additional legions were raised. From the doubling of the army during the Samnite Wars in the penultimate decade of the 4th century BC, there were normally four legions. The legion of the classical era emerged as part of the professionalization of the Roman army during the 2nd century BC, associated in traditional historiography with the so-called army reforms of Marius. With these reforms, the transformation of the legion from a citizen army to a professional army also took hold. During his time in Gaul, Gaius Iulius Caesar had eight to twelve legions, some of which he had raised himself (56 BC). In the turmoil of the civil wars, the number of legions grew to about 70, though often with reduced strength. Emperor Augustus created a standing army whose legions were stationed in the provinces on the borders of the empire. For a long time in the imperial period the total number was about 30 legions. In the late period of the Roman Empire, the heavy infantry of the legions became less important, especially compared to the cavalry. In the course of the Diocletianic and Constantinian reforms, which marked the last heyday of the classical Roman army, the legions were reduced to total strengths of often less than 1000 men, but their numbers were increased to about twice that.

In the classical period, the legions usually operated together with auxiliary troops, usually in roughly equal numbers, who were initially provided by the Italic confederates and other subjugated peoples and later recruited in the provinces and consisted of peregrines (provincial inhabitants) without Roman citizenship. They essentially provided the contingents of mounted men, archers, and slingers, in addition to additional infantrymen. The auxiliary troops were not part of the legion, but were led by it in action and directly supported it with their specialized skills. After Emperor Caracalla's civil rights reform in 212, which placed all provincial inhabitants on an equal footing with Roman citizens, the distinction between legionary and auxiliary troops was also increasingly abolished in the army and lost its significance.

Roman legions existed from the 6th/5th century B.C. to the early 7th century A.D. During this long period they were subject to considerable changes in strength, composition, equipment and deployment. In the West they disappeared in the course of the 5th century, in the Eastern Roman Empire then finally in the 7th century with the transition from the late Roman to the Byzantine army.

See also

• List of ranks and types of troops in the Roman army
• Legion Camp
• List of the Roman legions
• Thebaic Legion
• Roman Navy
• Roman fighting technique
• Military law in ancient Rome