How was the growth of the republic aided by the roman army's use of legions in warfare?

Back in that time, the Roman Army was considered to be the most advanced army in strategy, ect. They created the Roman Empire. However, Rome itself, actually benefited from them because of the money and treasures brought back from the territory's that they conquered.

The Roman's would divide and conquer because legions were faster than traveling in one huge group. Because they were faster, they could take over the enemy city, state, or country. The more they defeated the more prosperous they became.

What biome? i can just which