The Fire Nation cruiser is a type of formidable steam-powered warship that makes up the bulk of the Fire Nation Navy. Heavily armed and armored, the cruiser was the most powerful and advanced warship used by any of the four nations during the Hundred Year War, and as such, saw prominent use by the Fire Nation in its assaults on the other nations.
The oldest known model of the Fire Nation cruiser was already in use at the beginning of the Hundred Year War. One of these ships was immobilized by waterbenders during the Southern Water Tribe raids and became the shipwreck of the South Pole. Later, a cruiser of this particular class fell into the hands of Prince Zuko, who used it to search for the Avatar and, upon his discovery of Aang, to chase after him.
By the time the Avatar had returned, the Fire Navy deployed enough of these vessels for Commander Zhao to maintain an elaborate Fire Navy blockade, although the blockade failed to stop Aang from getting through right before the winter solstice. Zhao, after being promoted to admiral, later used his fleet to prohibit access to a bay through which he was searching for the Avatar.
The largest known engagement in which the cruisers participated was the Siege of the North. Realizing that the Avatar was heading north to complete his waterbending training, Zhao gathered a "massive invasion force" to launch an attack on the Water Tribe while Aang was there. This grand armada consisted of hundreds of Fire Nation cruisers, as well as Zhao's larger flagship. The battle commenced by bombarding the massive ice wall protecting the city with fiery projectiles shot from the ship's trebuchets, then several cruisers closed in to land a force of firebenders, tundra tanks, and komodo rhinos. Aang remarked that he took out at least a dozen of the cruisers, but that there were just too many ships. Despite this, the battle ended in a disaster for the Fire Nation, as an enraged La, the Ocean Spirit, merged with Aang and destroyed the entire fleet.
Even after this battle and the tremendous material loss for the Fire Nation, cruisers remained a common sight in the Fire Navy. The ships were known to patrol the Fire Nation controlled Western Lake, near Full Moon Bay and the Serpent's Pass, and after the fall of Ba Sing Se, they patrolled the whole bay.
One of these patrol ships was hijacked on Sokka's suggestion by Team Avatar and the Southern Water Tribe warriors, who used it to escape the bay without notice by the Fire Nation when they needed to hide to give the fallen Aang time to recover. They were intercepted by another cruiser, and after a failed attempt at trickery, the second cruiser gave chase. Toph launched boulders at the enemy cruiser to disable its weapons, but the cruiser was able to damage the hijacked ship and pierce through the hull underwater with a harpoon. Katara used her waterbending to temporarily seal the hole with ice and form some fog for cover. Eventually the giant sea serpent appeared, and attacked the pursuing ship, allowing the hijacked ship to escape. When Aang tried infiltrating the Fire Nation soon after, he was forced to dive under the blockade of Fire Nation cruisers that guarded the border of the Fire Nation waters.
The Fire Nation cruiser is an example of the Fire Nation's advanced technology and industry. Each cruiser is fueled by the combustion of coal, the exhaust of which comes out of two smokestacks. The power provided by the coal in turn rotates propellers under the stern of the ship, allowing for propulsion not dependent on wind or currents.
Below deck, the cruisers have considerable cargo carrying capacity. This allows the ships to function as transports, shuttling soldiers, equipment, even tanks and komodo rhinos, wherever they need to go. Cargo and passengers are usually sent ashore via the spiked bow that lowers to form a ramp. Cruisers can also deploy smaller oceangoing craft from a bay in the back of the ship. Above deck is the impressive conning tower, containing the high-ranking officers' quarters and the bridge.
Above all else, the Fire Nation cruiser is a warship, and this is reflected in its heavy armament. Modern cruisers are armed with trebuchets, loaded with boulders covered in a highly flammable oil. Before discharging the trebuchets, firebenders ignite the oil, resulting in a lethal and intimidating projectile. Special crew members maintain and operate the trebuchets. Some variants of Fire Nation cruisers are armed with three trebuchets in a line along the deck, while others are armed with five. Cruisers can even be armed with ballistae, which launch harpoons and explosive shells.
There are many variants of the Fire Nation cruiser.
- Empire-class battleship - An enormous battleship twice the size of a cruiser. This was Zhao's flagship during the Siege of the North.
- Old Fire Nation cruiser - This smaller and older variant of the cruiser was taken out of official service by 100 ASC. However, one of these ships was used by Zuko to follow the Avatar until its destruction.
- Royal barge - A large decorative ship used for transporting royalty. Azula and Ozai were both known to travel on one.
- Southern Raiders frigate - A smaller and faster ship used by the Southern Raiders unit for raiding the Southern Water Tribe.