Quote Originally Posted by A.Saturnus
As others have already pointed out, supply lines weren't as important than as in later warfare. Armies lived mostly of the land, which is in Rome represented by the devastation they cause.
History is filled with examples of generals attacking supply bases or engaging in a "scorched earth" policy, leaving nothing for invaders to eat or supply with.

The result is a need for supply lines, which poor nations have difficulty sustaining.