Early campaigns centered on the Italian peninsula before expanding into Sicily, North Africa, Spain, Greece, and Asia Minor. Later conquests reached Gaul, Britain, the Balkans, Egypt, the Levant, and parts of Mesopotamia. The Mediterranean linked the empire's provinces, while the Rhine, Danube, and eastern borderlands became major military frontiers. Roads, rivers, ports, and mountain passes supported the movement of legions and the administration of conquered territory.