The Fire Nation serves as the series antagonist in Nickelodeon's Avatar: The Last Airbender, an ambitious kingdom with a penchant for world domination. Over the three seasons of the animated television show, the Fire Nation has committed some pretty atrocious crimes both in the forward story and the tales of the distant past.

RELATED: Myers-Briggs Personality Types Of Avatar: The Last Airbender Characters

Led by the tyrant Lord Ozai, the world lives in fear of the fire bending army and their advanced technology, which sweeps across the globe subduing everything under their feet. What are some of the worst crimes Fire Nation has committed in the process? Here are the top ten according to CBR, ranked.

10 The Siege Of Ba Sing Se

The Siege of Ba Sing Se is one of the show's more infamous moments. The city serves as Earth Kingdom's global capital, and a major center of commerce and industry in the world of Avatar in general.

The siege itself took place during a campaign led by Fire Nation's General Iroh, who finally managed to breach the outer wall after a six hundred day assault. However, despite Iroh's best efforts, the city's defenses held, forcing the wizened warlord to abandon the invasion until a later time.

9 Attempted To Murder Aang

aang in avatar the last airbender

What would Avatar: The Last Airbender be if Fire Nation weren't constantly making attempts at Aang's life. After all, the child prodigy is the only living Avatar -- capable of bending all four elements of each tribe. In other words: Aang is Jesus, so naturally, Fire Nation wants him dead and buried as soon as can be.

RELATED: 15 Reasons Avatar: The Last Airbender Is An Anime

Thus, Aang is constantly living under threat of assassination, fending off one attempt after the other throughout three seasons of television. However, fortunately for the Avatar, these attempts are easily thwarted thanks to help from his friends.

8 Built Machines Of War Capable To Obliterate Its Enemies

Another dastardly deed committed by the Fire Nation is its construction of machines of mass death. The machines were built during the reign of Azulon the Great, father of Ozai and grandfather of Prince Zuko, who was renowned for his military prowess and ruthless nature.

Whether it's tanks, warships, fire harnessing projectiles, or battleships capable of sailing across the world at high speeds, the Fire Nation has dealt many deadly blows to the Earth Kingdom and the Water Tribes of the north and south. The machines continue on during the reign of Ozai, securing great victories for the Fire Lord and expanding the empire.

7 Demolished The Southern Water Tribe

One of the major causalities of the Hundred Year War was the annihilation of Southern Water Tribe -- a peaceful people who dwelt in the glacial ice lands of the South Pole. The tribe, like their northern counterpart, joined the Hundred Year War and contributed to some major battles within the campaign.

RELATED: Avatar's Most Powerful Nation Wasn't the Earth Kingdom OR the Fire Nation

However, unlike the Northern Tribe, the south suffered major losses, facing a genocide similar to the air nomads years prior. Fortunately, the south survived, though few in numbers thanks to the wrath of the fire benders.

6 Colonized Much Of Earth

aang fire nation

It's no secret colonization is a great evil that has done much damage in the real world. The same is true for the Avatar universe as the Fire Nation sought to bring all four kingdoms under its rulership.

One way the legion of fire benders did this was through the process of conquering cities and then populating them with their own people, forcing native survivors to adopt the Fire Nation's culture, customs, and general way of life. However, despite their earnest efforts, the Earth and Water Tribes fought back, resisting the Fire Lord's will at nearly every turn.

5 Killed Avatar Roku

Avatar Roku in the Avatar State in The Last Airbender.

This little atrocity is brought to you by Fire Lord Sozin who participated in the death of Avatar Roku when he left his old friend to die on a volcanic island. Ironically, this was an act of civil war on Sozin's part as Roku was the first avatar to arise out of the Fire Nation itself -- one who Sozin envied due to Roku's great abilities.

RELATED: Avatar: The 25 Most Powerful Characters In The Universe, Ranked

The slaying occurred after a major volcanic eruption on an island chain, trapping Avatar Roku and encasing him with toxic fumes. When Sozin arrived to save his mentor and friend, he decided to eliminate Roku by leaving him to die, believing that with the Avatar out of the way, there would be no one to stop him in his quest for Fire Nation supremacy.

4 Captured the Water Spirit To Demolish The Northern Water Tribe

Zhao smile in Avatar

Led by Admiral Zhao, the siege of the North Pole was an attempt to completely destroy the Northern Water Tribe, kill the exiled Prince Zuko, and capture Avatar Aang. Knowing that the water tribe received their powers from the moon, Zhao captured the moon spirit which turned the sky red, resulting in all water benders losing their powers.

Because of this, Zhao was allowed to move forward unchecked, ravaging the water tribe with flame and steel. If it weren't for the avatar and allies like General Iroh himself, Zhao would have likely completely wiped the tribe off the face of Earth.

3 Scorched Earth Kingdom With Sozin's Comet

Despite being the largest of the four kingdoms, the Earth Benders were easily overtaken by the unrelenting tenacity of Fire Nation. Several cities fell as the Hundred Year War raged on, losing strongholds such as Ba Sing Se.

RELATED: 15 Best Avatar: The Last Airbender Characters

When it comes to worst lists, subjugating the Earth Kingdom is one bad feat. Not only this, but Lord Ozai used Sozin's Comet to burn the kingdom to the ground, killing many earth benders in the process.

2 Started The Hundred Year War

A map showing the Four Nations: Water Tribe, Fire Nation, Earth Kingdom, Air Nomads, in ATLA.

This is the event that started it all. The Hundred Year War was an invention of none other than Fire Nation's Lord Sozin, designed to expand the empire and bring the four tribes under one banner. Under Sozin's leadership, the Fire Nation kicked off its campaign by murdering the entire tribe of air nomads, setting the tone for what was to come: a scorched Earth gauntlet of blood, death, and destruction.

For the next one hundred years and three Fire Lord's later, the campaign comes to a climax as a new avatar arises to unite the tribes. But with each life the nation of fire benders claims, the stronger they become, leaving the world wondering if even their new avatar can save them.

1 Genocide of Air Nomads

Speaking of Sozin, this is obviously the worst thing Fire Nation has ever done: eradicating the entire race of air nomads. It is this atrocity that kicks off the infamous Hundred Year War, leaving Aang the last Airbender frozen in ice while the nation of fire-wielders executes its scorched earth war.

As mentioned above, Fire Nation subdues the Earth Kingdom and then nearly kills off the southern water tribe in the process, establishing itself as one of the most feared entities in the Avatar universe.

NEXT: Avatar: The Last Airbender: 10 Life Lessons That Are Still Relevant Today