C81 Solving difficulties with small trial

The ballista was a chariot equipped with a crossbow. The ballista stood in formation and used a flag to block the ballista. The ballista had a bed crossbow on it, and the crossbow was as big as a ballista.

The ballista could be said to be the most powerful and lethal weapon in the era of the cold weapons. "The power and range of a catapult is far less than that of a ballista