The ballista is a large crossbow-type weapon that uses torsional force to propel a variety of projectiles, including darts, arrows, and harpoons, much farther and faster than a catapult or similar device. It is mounted on a rotating platform aboard a Fire Navy ship, similar to the catapults and trebuchets also seen on those ships. The weapon is mainly used to fire a metal projectile into the hull of an enemy's vessel at a point below the water line. Once the hull is breached, the projectile opens up to prevent itself from pulling free.
This weapon was used by a Fire Navy officer's ship when its crew tried to destroy a Fire Nation ship that was captured by Team Avatar. Several ballistae were utilized during the invasion to hinder the advance of the waterbending-powered submarines toward the Royal Plaza. One managed to puncture one of the submarines before Katara sliced the chain of the projectile. It was later used at the Boiling Rock to pull in a cooler that Chit Sang, his girlfriend, and another inmate had attempted to escape in.
- ↑ 1.0 1.1 "The Awakening". Aaron Ehasz (writer) & Giancarlo Volpe (director). Avatar: The Last Airbender. Nickelodeon. September 21, 2007. No. 1, Book Three: Fire
- ↑ "The Day of Black Sun, Part 1: The Invasion". Michael Dante DiMartino (writer) & Giancarlo Volpe (director). Avatar: The Last Airbender. Nickelodeon. November 30, 2007. No. 10, Book Three: Fire
- ↑ "The Boiling Rock, Part 2". Joshua Hamilton (writer) & Ethan Spaulding (director). Avatar: The Last Airbender. Nickelodeon. July 16, 2008. No. 15, Book Three: Fire