onsisting not of the annexed provinces but of all the territory over which Rome exercised power.
The nature of the system of defense used by the romans serves as a rationale for some of the expansion and fits with the idea that the Romans were not consciously attempting to expand their power. The imperial system of defense is described by Luttwack, and he sees it as surprisingly less controlled and less comprehensive than might be believed considering the degree of success it had and the stability it enforced. In the early period, the army was used primarily for defensive purposes, to provide security against the sudden emergence of unforeseen threats. Luttwack says that such threats were primarily internal. There were sporadic transborder incursions by Germans, Dacians, and Sarmatians. The major security problems for Rome, however, came from internal native revolts. What was done was to create several instruments of strategic control that enabled Rome to maintain overall stability and to put down, discourage, or lessen the impact of these internal revolts--as long as there was no credible outside force to threaten the borders, relative stability coul
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