During the time of the Roman Empire the Roman military was a very powerful "military war machine"(Nardo 259) that conquered most of the known world of that time. The Roman military of the Empire was the best-structured, organized, and maintained military through 31BC-400AD. According to the size of the Roman Empire, which was about 50 million people, the military was relatively small. The Roman military consisted of three main branches: the legions with the auxilia, the Praetorian Guard, and the fleet. Each branch of the Roman military had its own distinct features, which made them different than the others. Due to its structure and leadership it became the greatest power in its time.
             The units called legions formed the core of the Roman army. During the first three centuries of the empire the army contained no more than 25 to 34 legions. Each of these units consisted of about 5000 to 6000 men recruited among the citizen body. "The legion was subdivided into ten regiments know as cohorts and these cohorts were grouped again into centuries"(Mills 418). A centurion who was appointed by the emperor commanded each century. Although the soldiers of the legion were Roman citizens, this did not mean that they were born in Rome. With the rise of population through the conquered territories provincials quickly became the most important source of new recruits for the auxilia. Roman legionary soldiers generally enlisted for a term of twenty years and on the date of discharge legionaries were given 3,000 Denarii in addition to land for retirement. Most discharged legionaries regularly settled in colonies throughout the empire.
             The legions were miniature armies that contained within its rank troops "trained and equipped to perform all kinds of different duties both on and off the battlefield" (Tingay 312). Although the vast majority of soldiers served as heavy infantry, other legions fought as cavalry, arche...