Roman soldiers came from all parts of the Roman Empire. They were loyal, because they chose to become soldiers. Also, after at least twenty years’ service, soldiers were given either some land or a large amount of money, or both.
The Roman army developed some advanced weapons, which also helped them conquer new lands. They used powerful sling-shot catapults to smash the walls of castles. Rocks were loaded into a sling at the end of a long wooden post. This was then pulled back like a spring and released.