They had a number of war machines including the ballista, which was a giant crossbow-like weapon with two levers, torsion springs, and a slider where the ammunition would be loaded. It was originally a Greek invention the Romans improved it. The ballista was used by Julius Caesar a lot.

Another war machine used by the Romans was the Onager, which also used torsion for power like the ballista. But unlike the ballista, the onager was mainly used as a siege engine to destroy fortifications and buildings. The onager was a type of catapult that had a large frame on the ground, a vertical frame on the front, and an arm in the middle. The onager was used to throw big stones. It was famously used against the Greek city states during the siege of carthage.