The Coup of Ba Sing Se, also known as the Fall of the Earth Kingdom and the Fall of Ba Sing Se, was an event in 100 ASC, when Princess Azula of the Fire Nation, along with her friends, Mai and Ty Lee, disguised as Kyoshi Warriors, infiltrated the Earth Kingdom capital city of Ba Sing Se, took control of the Dai Li, and orchestrated a coup of the 52nd Earth King. It was a major defeat for the enemies of the Fire Nation. This coup brought Ba Sing Se and the Earth Kingdom under Fire Nation control, and was the final major military operation of the Fire Nation in the Earth Kingdom, until the coming of Sozin's Comet a few months later. This event also caused Azula's brother, Prince Zuko to join her coup and return to the Fire Nation.
Aang and his friends decided to go to Ba Sing Se after they returned from the Si Wong Desert. This was partly because Sokka had discovered that Firebenders lose their bending during a solar eclipse from information gathered at Wong Shi Tong's Library and needed to tell the Earth King, and partly because Appa had been stolen and sold to merchants, and would likely be taken to Ba Sing Se.
After getting out of the desert the group took a deadly route to get to the Outer Wall, and foiled a Fire Nation plan to invade the city. Once they finally got into the city, however, they discovered that all was not as it seemed. Long Feng, Grand Secretariat of Ba Sing Se, was using his Dai Li agents to keep knowledge of the war suppressed and was controlling the city by manipulating the Earth King.
Zuko and Iroh had also entered Ba Sing Se, but as unnoticed refugees. However, Jet suspected that they were Firebenders. Iroh quickly gained a reputation as the "best tea-maker in Ba Sing Se". Unable to stand observing Iroh and Zuko fail to Firebend any longer, Jet declared that Iroh and Zuko are Firebenders at the tea shop at which Iroh and Zuko worked, and engaged Zuko in a sword duel. Jet was then captured by the Dai Li and brainwashed.
Team Avatar made a sustained effort to find Appa. While the group were pasting flyers to walls around the city, they discovered a brainwashed Jet and later, two members of the Freedom Fighters. After making Jet recall earlier memories, the group infiltrated the Dai Li base in an attempt to rescue Appa. They fail however, and Jet is killed. Meanwhile, after harsh words from Iroh, Zuko freed Appa from his prison beneath Lake Laogai. Appa flew out and immediately rescued Team Avatar from the Dai Li before reuniting with Aang.
The Avatar eventually confronted the Earth King, successfully proving to him both that the Earth Kingdom was at war, and that Long Feng was corrupt. Long Feng was imprisoned, pending trial for crimes against the Earth Kingdom, but was soon satisfied that the Dai Li were still loyal to him.
Princess Azula and her friends Mai and Ty Lee were tracking the Avatar using a fur trail Appa left behind. However, instead of finding Aang, she found the Kyoshi Warriors who were taking care of Appa. Declaring that any friend of the Avatar was an enemy of theirs, Azula and her friends successfully attacked and captured the warriors, sending them back to a Fire Nation prison. Making a plan to infiltrate Ba Sing Se, Azula and her friends donned their uniform.
Team Avatar meanwhile had just received various pieces of good news and had split up temporarily, mostly for personal goals. Two had even left Ba Sing Se. Azula and her friends were thus able to penetrate the city without coming under the scrutiny of Aang and his friends, which would have surely exposed them. Instead, Azula was welcomed warmly by an unsuspecting Earth King.
Having successfully infiltrated Ba Sing Se without meeting her most obvious obstacle, Azula immediately set to work on a plan for a coup knowing that the Dai Li were listening to the three's conversations. When arrested by the Dai Li, Long Feng talks to her from inside his prison cell and the two agree on a plan to overthrow the Earth King and the Council of Five by temporarily handing control of the Dai Li to the Fire Nation Princess. Azula agrees to this with plans of betrayal forming in her head.
An immediate threat to Azula's planned coup was Katara who had direct access to the Council of Five and the Earth King and could inform them of threats. Katara was quickly eliminated however because she did not realize who they actually were at first sight and blurted out that Zuko and Iroh were in Ba Sing Se. Ty Lee quickly blocked her chi and Katara was thrown into the Crystal Catacombs of Old Ba Sing Se.
Now with the knowledge that her uncle and brother were in the city, Azula attempted to remove them as threats. She lured them to the Royal Palace by telling them through a letter that the Earth King had asked them to serve tea to him. Although partially successful, Azula failed to capture her uncle who escaped after breathing fire against the Dai Li agents to buy time. She does however capture Zuko and the Dai Li throw him into the catacombs.
Aang and his friends had meanwhile returned to Ba Sing Se because of Aang having a vision that Katara was in danger. The Earth King reassures them that she is alright. Aang and his friends' fears were quickly realized when they returned to their house, which was empty. Iroh then arrived moments later pleading for their help. After finding out crucial information from a captured Dai Li agent, Aang and Iroh go to rescue Zuko and Katara from the Crystal Catacombs while Sokka and Toph rush to the Earth King to inform him of the planned coup.
Sokka and Toph were too late despite their efforts. Having already done an "inspirational" speech, Azula had put the plan into action. Sokka and Toph watched as General How was placed under house arrest. Rushing into the throne room, they tried to inform the Earth King, but were also too late, and when Azula threatened the Earth King's life, the two surrendered and were thrown into prison along with the Earth King.
A freed Long Feng then appears in the throne room with his Dai Li agents, and unsuccessfully ordered the Dai Li to arrest Azula. Azula then explains the situation to Long Feng; the Dai Li didn't know which of them is more powerful. She guesses that he is lower class by birth, but had managed to get his power through incredible work all his life; however, she declares that she has “divine right to rule,” and confidently takes the Earth King's throne. Long Feng surrenders, bowing to Azula, admitting how she beat him at his own game. Azula replies that he was never even a player.
In the catacombs, Katara and Zuko have a deep discussion with unprecedented civility, and Katara offers to use her Spirit Oasis water to heal Zuko's scar. They are interrupted however by their rescuers, Aang and Iroh. Zuko is not impressed by the Avatar's presence, questioning his uncle about it. After Aang and Katara quickly leave to help Sokka and Toph, Iroh attempts to convince his Zuko to turn to good, but is interrupted in turn by the arrival of Azula, whose Dai Li agents trap Iroh in crystal. Azula then tells Zuko that he could gain his honor and their father's love by helping him with her final obstacle to a successful coup, the Avatar, before leaving to intercept Aang, leaving Zuko pondering his options.
Battle in the Crystal Catacombs Edit
Aang and Katara rush to save Toph and Sokka, however, Azula finds them and attacks them, beginning a short engagement eventually resulting in Azula feeling fearful, being clearly outmatched. Zuko appears, but instead of fighting Azula, which would certainly bring about her defeat, he attacks Aang. He and Aang fight evenly, but Azula is outclassed by Katara. Eventually, in the midst of the battle, the two pairs switch, with Zuko now fighting Katara, both using element whips on opposite sides of a river. Azula and Aang charge at each other, but Azula quickly knocks him to a side.
Back in the Palace, Ty Lee is trying to teach Bosco the Bear how to walk on his front legs, but she soon is trapped by Toph. Toph and Sokka take a fighting stance against Mai, who in her nonchalance says to take the bear, and the King reunites happily with his pet.
Underground, Katara fights both Azula and Zuko, before Aang manages to get back up from being thrown earlier. He attempts to advance towards Azula and Zuko but is stopped by the Dai Li. They are soon joined by dozens of Dai Li agents, and Katara assumes the Octopus stance. Horribly outmatched, Aang realizes there is no other choice and creates a crystal shelter, attempting to enter the Avatar State. He nearly succeeds, but as he rises into the air, Azula shoots him in the back with lightning. Katara stops him from falling to his death. Iroh suddenly appears, tells the two to escape, and states that he will hold the enemy off. Once they escape, Iroh surrenders himself to the Dai Li.
Team Avatar successfully escapes from Ba Sing Se, and Aang is revived with Katara's spirit water. However, as the Earth King sadly states, "The Earth Kingdom, has fallen".
Azula's successful coup in Ba Sing Se had significant repercussions for the rest of the Earth Kingdom, which was severely weakened by the loss of their last great stronghold. The Earth Kingdom military in particular was damaged, as their leadership, the Council of Five, was arrested. The victory was so complete that Katara remarked later that "the Fire Nation pretty much won the war when they took Ba Sing Se".
With the fall of the Earth Kingdom, the Water Tribe became the last of the Four Nations yet to be conquered by the Fire Nation. However, given the losses they suffered during the war and their small army, they alone could not hope to defeat the Fire Nation.
The coup also dealt severe damage on a strategic level to the plan to invade the Fire Nation. It reduced the number of troops available to carry out the operation. Hakoda, under the direction of his son, was only able to gather a small "rag-tag" force for the invasion.
After Avatar Aang was defeated in the battle, much of the world believed him to be dead and many lost hope that the war could be won. Aang himself remained unconscious for weeks afterward and the lightning blast disabled his ability to enter the powerful Avatar State. The only advantage gained from this defeat was that the Fire Nation would not expect his intervention during the aforementioned invasion.
During the time that Aang was recovering the Dai Li, using Earthbending, bring down the great walls of Ba Sing Se and the Fire Nation invades soon after, signifying that the Earth Kingdom had fallen.
Zuko was now able to return to the Fire Nation, and was honored by his father and his people. However, he begins to regret betraying his uncle almost immediately.