Earthbending-powered tank

Earthbending Powered Tanks, nicknamed by some as Earth Kingdom Tanks or Slinky Tanks, are vehicles owned and operated by the Earth Kingdom Military. They first appeared at the Invasion of the Fire Nation, after they were designed by Sokka and the Mechanist.

History
The Earthbending Powered Tanks were first proposed shortly after the fall of Ba Sing Se. Sokka of the Southern Water Tribe decided that if the Earth Kingdom and Water Tribes were going to invade the Fire Nation on the Day of Black Sun, they were going to need vehicles to mow down the defenses. Sokka designed the tanks himself and introduced his plans to the Mechanist, an expert inventor and ally of the Avatar's team. The Mechanist immediately set forth to start building these vehicles. In all, five tanks are known to have been produced.

During the Invasion of the Fire Nation on the Day of Black Sun, those five Earthbending Powered Tanks were deployed on to the shores of the Fire Nation Capital from the Waterbending Powered Submarines. The tanks proved amazingly durable and were able to withstand repeated attacks by opposing Fire Nation tanks. They crushed many of these tanks and entire bunkers, as there were dozens of these small structures lining the Capital grounds. The tanks got the invaders to the Royal Plaza and then proceeded up to the Royal Palace.



During the invasion, these tanks once again overwhelmed enemy troops and eventually captured the Palace. Unfortunately, the Fire Nation was ready for the invasion and once the solar eclipse ended, the Fire Nation launched a fleet of airships to drive out the invaders. The invaders tried to escape the Capital in their tanks, but it was too late to reach the submarines, as the airships destroyed these crafts with their bombs. After the invasion failed and the Avatar's group escaped, the invasion force was left behind to surrender to the enemy.

The tanks all survived the battle, but it is unknown what the Fire Nation has done with these vehicles. Due to the fact that they are not capable of Earthbending, the Fire Nation likely stored away these vehicles or scrapped them to use as materials for new vehicles.

Now that the War is over, it is unknown if these tanks will enter mass production in the regular Earth Kingdom Army due to the lack of fighting currently going on. However, such a vehicle could be a crucial weapon in future conflicts.

Design
Earthbending Powered Tanks are multi-segmented tracked vehicles powered by four Earthbenders. the treads are made of plates of earth strung togeter by a metal wire, which is how the Earthbenders can control the tank. They can carry many troops and can cross over almost any terrain. Their armor is invulnerable to fire, making them ideal for assaults on enemy positions. Powered by Earthbending, these tanks can be manipulated to crush enemy targets, including tanks and even small bunkers. They can swerve around enemy forces easily and make good shields for ground troops. They even sport side hatches that open up so that Earthbenders can launch projectiles like rocks and boulders at enemy troops.

Weaknesses
If Earth Kingdom Tanks are knocked on their sides, they are helpless on the battlefield until they are set up straight again. However, they can be used as cover in the meantime.

Trivia

 * Earthbending Powered Tanks are inspired by caterpillars.
 * Earthbending Powered Tanks were inspired by one of Leonardo da Vinci's tank designs.