Roman Siege Weapons ... Designed to overcome fortified positions and enemy defenses. Some of the most notable Roman siege weapons include: Ballistae: These were large crossbows capable of launching bolts or stones over long distances. They were used to breach walls and fortifications, as well as to target enemy soldiers. Ballistae were known for their precision and could be adjusted for different ranges and types of ammunition. Onagers: Also known as "wild asses," these were torsion-powered cata