No rivers divided the western part of the Roman empire. If you mean what rivers formed the frontiers of the this part of the Roman Empire, they were the Rhine and the upper Danube. In between them there was the limes germanicus, a line of fortifications which crossed southern and central Germany.

No military activity is allowed on the Antarctic continent, according to the Antarctic Treaty.

The Roman soldiers built the stone-paved road, which had a military purpose, other roads which had a military utility, fortifications and garrisons when they were not campaigning. Since they were professional soldiers, when they were not campaigning their spent their time drilling and training and in construction work needed by the military.

The Roman emperor Marcus Aurelius (121-180 AD).

why did the roman military form