Rome’s prolonged success was largely due to their political innovation and their ability to effectuate it on such a large geographic scale. Both the governments of the Republic and the Empire enjoyed a massive array of political achievements—but their unparalleled defense system and their general knack for foreign diplomacy were important components to their overall success.

Rome’s political achievements were largely possible because of their unmatched military capacity. In their initial acquisition of land throughout the Italian peninsula during the early Republic, they secured military manpower by recruiting conquered peoples to join the Roman alliance army in exchange for protection and a share in the profits from victories. Allies naturally turned to Rome whenever their interests were threatened, so they complied with this arrangement long enough for Rome’s military to acquire the necessary momentum for eventually dominating huge territories around the Mediterranean. Because of its highly evolved sustainability, the Roman army can be described as a self-perpetuating war machine that was very effective with protecting its people.

Earlier in history, the Romans were perceived as destructive bullies—but their diplomatic tactics later evolved to become more sophisticated to accommodate for the vast amount of conquered lands and peoples. By the time of the Empire, Rome had established such productive incentives for submitting to their dominion, that many kings were more or less content to be their subordinates. For example, Roman foreign policy became more focused on preserving a degree of power for domestic kings over their own people, allowing them to maintain their traditional culture. Over time, the cultural influence of Rome slowly filtered throughout conquered territories, thereby avoiding instant widespread foreign resistance. Thus, the Romans learned how to create a pragmatic and organized foreign diplomatic system that was very innovative for its time and arguably one of their most valuable political achievements.