National militaries extend operational reach through the use of improved lines of communication and basing. Evidence of Roman roads and fortifications in Gaul reveals a history of physical infrastructure extending operational reach in order to increase the Roman Army's chance of success. This comparison of the Roman roads and basing in ancient Gaul to the modern concept of operational reach and its components (momentum, endurance, and protection) emphasizes the impact of infrastructure on military operations. Three case studies provide a framework for this study. First, Caesar's legions used Gallic folkways to fight in Gaul from 58-50 BC, which caused challenges to momentum, endurance, and protection limiting operations. Second, the Romans projected all forces for the invasion of Britain over roads in Gaul in 43 AD. Third, from 19 BC until the fall of Rome in the fifth century AD, the Germanic frontier exchanged almost all possibility of momentum for a substantial increase in endurance and a significant increase in protection to the greater empire. All three periods of Roman operations in Gaul demonstrate the interplay of the components of operational reach. The increase in one element, in most cases, will cause the drop of another unless technology or infrastructure increases them all. Poor roads and basing restricted Caesar's potential operational reach in Gaul. The deployment toward Britain over Roman roads in Gaul succeeded due to significant increases in infrastructure allowing greater endurance and momentum. On the static frontiers of the Roman empire, the army greatly reduced the potential momentum of its forces as a trade-off for greater endurance and protection.

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