An empire, if you can keep it

National Interest, The, Spring, 2003 by Stephen Peter Rosen

The formation of a monopoly on military power is greatly facilitated by the decision of other potential powers not to compete. The Roman Empire effectively had two components, one in the west and one in the east (centered on Byzantium). As is well known, the eastern empire persisted long after the sack of Rome in 476 CE. Less well known is the fact that the internal factors associated with the fall of the Roman Empire -- the rise of Christianity, increasing social rigidity and the bureaucratization of imperial governance -- were just as powerful in the east as they were in the west. The difference was that there were fewer organized military challenges in the east, and the one potential challenger to Byzantium, the Parthian Empire, chose to accept Rome's dominant role. (3) Similarly, the British monopoly on seapower began to emerge in the early 18th century, when French Continental concerns led to the virtual disappearance of the French battle fleet. The withdrawal of competitors was even more marked followi ng the wars of the French Revolution, at which time British naval mastery rested, according to Paul M. Kennedy, on the "simple wish of other nations not to spend the time or energy to challenge the British." (4)

The same phenomenon is at work today. The American empire did not emerge simply as the result of the growth of American power, but as a result of the collapse of Russian power, the decline of European and Japanese military spending relative to the United States, and the unwillingness of those countries to take military action or make military preparations in response to a host of security problems. A surprising number of major states are not now engaging in the self-help that Waltz says is at the heart of interstate relations, but are relying instead on the United States for their security.

The creation and maintenance of a U.S. monopoly, or near-monopoly, on organized military power could not and did not arise simply from the abdication of non-imperial powers, however. Historically, either enduring differences in the social organization of imperial versus non-imperial states, or active and effective imperial strategies, have led to gross disparities in military power. The ability of republican Rome to develop military power from a population of free adult males from Rome and its Italian allies (totaling approximately 2.75 million men) was the basis of Roman expansion. From this base it built an army that controlled an imperial population of approximately fifty million people. Rome's ability to develop more military power than its rivals rested primarily on the organizational practices of the Roman Legions, which created a unified and coordinated fighting force that could routinely defeat opposing armies five times its size. Drill and discipline produced formations that could withstand uncoordin ated infantry and cavalry attacks mounted by less well-organized adversaries. The internal divisions and lack of social cohesion among the rivals of Rome, with the exception of the armies of Hannibal, created an enduring military advantage that cascaded over time, for as Rome's area of control expanded, the population base from which it could draw military recruits expanded, too. (5)