In the third century of the Common Era (CE), when Rome dominated not only Europe, but also North Africa and the Near East, it was able to deploy fifty legions throughout the empire. In this forward defense strategy even the furthermost areas of the empire were secured by the on-site presence of an adequate number of legions of the Roman army. However, the empire had lost much of its muscle by the fourth century CE and the forces of Rome had diminished to only about twenty-five legions. It had thus become impossible to station legions in sufficient strength at all of the forward positions of the empire without.
