The Battle of Trost District (トロスト区攻防戦 Torosuto-ku kōbōsen?) was a conflict between humanity and the Titans in Wall Rose's southern district, in which humanity prevented the loss of Wall Rose and claimed its first victory against the Titans.
Two years after the fall of Wall Maria, the three surviving warriors of Marley, Bertolt Hoover, Reiner Braun, and Annie Leonhart, joined the 104th Training Corps. Their mission was to obtain the Founding Titan from the royal family in the interior and to wipe out humanity, and the top ten graduates of the 104th Training Corps would be given the privilege of joining the Military Police Brigade. After the three years of training, all three warriors were placed among the top ten, and they openly expressed to their comrades their desire to join the Military Police. On the night before the attack on Trost District, the southern territory of Wall Rose, the 104th Training Corps was formally disbanded.
Shortly after the departure of the Survey Corps, Bertolt Hoover transformed into the Colossus Titan, breaching the southern gate of Trost District as the 104th trainees cleaned the artillery atop Wall Rose, leaving an eight-meter hole. Eren Yeager, who had seen the Colossus Titan for himself during the fall of Wall Maria, confronted the Colossus in an attempt to kill it before disappearing as it did five years ago. However, Bertolt succeeded in escaping before Eren could land a killing blow. Immediately after the Colossus Titan's disappearance, the Trost Garrison initiated their strategy for dealing with a Colossus Titan appearance. As the trainees gathered for briefing, the citizens of Trost were immediately evacuated from the district before the Titans entered the district.
Under the command of the Garrison, the trainees were divided into squads assigned to various streets throughout the district. The main force of the Garrison took up the vanguard where the Titans would enter the breach, while the trainees were assigned to the middle guard for support and communication. The Garrison's elite soldiers took up the rear guard near the northern gate to ensure the best evacuation of civilians, and trainee Mikasa Ackerman was also selected for this position due to her exceptional performance in the Training Corps. It was made clear that desertion from the battle would be considered a capital offense and punishable with execution.
While Mikasa joined the rear guard, Eren was assigned to Squad 34 along with Armin Arlert, Thomas Wagner, Nac Tias, Mylius Zeramuski, and Mina Carolina. Soon into the battle, the Garrison vanguard was overwhelmed by the Titans and the middle guard was called into action. Squad 34 was quickly slaughtered by the Titans upon first contact, and Eren risked his life to save Armin. In the process, he was eaten by a bearded Titan, with his left hand and leg lost in the skirmish. In the belly of the Titan, Eren's Titan power inherited from his father was able to prevent his death. Out of the Titan, Eren's 15 meter Titan form emerged in a state of bloodlust. Eren's Titan would begin to roam Trost District, slaughtering any Titans it encountered. Armin, the last known surviving member of Squad 34, had not consciously seen Eren's Titan emerge due to falling into a state of shock after witnessing the deaths of his squad mates. He was later found by his friends from another squad.
To the north, the citizen evacuation came to a halt when Dimo Reeves, leader of the Reeves Company, attempted to haul an oversized load of goods through the north gate, preventing other citizens from evacuating. As an Abnormal approached the crowd, Mikasa killed the Titan and confronted Reeves, ordering him to allow the other civilians to evacuate. Reeves reluctantly complied, and the evacuation was completed shortly afterward. All soldiers and trainees were then given the order to scale the Wall out of the district. However, many trainees could not evacuate due to low amounts of gas in their vertical maneuvering equipment, which could not be replenished due to the supply depot having been overrun by Titans. As the trainees grew worried for their situation, Reiner, Annie, and Bertolt decided to wait for more Titans to gather before continuing in their plan to breach Wall Rose.
The Mysterious Titan
Rather than scaling the Wall, Mikasa joined the middle guard in search of Eren, only to receive the news that he had been killed in action with the majority of Squad 34. To cope with the news, Mikasa left to kill more Titans as her comrades joined her, though Mikasa ran out of gas soon afterwards and was left alone. As a Titan approached to eat her, Eren's Titan by chance came across her at the same time and prevented her death. Armin pulled Mikasa away from the scene, and together with Trainee Connie Springer he proposed an idea to make use of the mysterious Titan to lead an attack on the supply depot for the evacuation of the trainees.
As the conflict in Trost played out, news reached the Survey Corps of the Titans' sudden movement northwards. Fearing another breach in the Wall, Commander Erwin ordered a retreat to provide support for the Trost District Garrison.
Upon discovering Eren's Titan, thought to be an Abnormal by the trainees, Armin and the others navigated their way through Trost to the supply depot with Eren's Titan following on instinct. At this same time, Jean Kirstein led the surviving trainees to the supply depot in a do-or-die attempt to retrieve the much-needed gas. Once all trainees had arrived at the depot, they made their way to the supply room and, with a strategy formulated by Armin, cleared out the seven Titans that had infiltrated the room as Eren's Titan brawled with the other Titans outside. As the surviving trainees evacuated over the Wall, some stayed behind after noticing that Eren's Titan had become overwhelmed by Titans, who had begun to feed on his body. The Titan regained some strength after spotting the Abnormal Titan that killed Thomas Wagner, killing it in a rage before collapsing to the ground, having killed a total of 20 Titans in his own Titan form. The trainees who witnessed Eren's emergence from his Titan brought him to Captain Kitz Weilman. Mikasa and Armin remained by his side, and the others who left to regroup with the other trainees were forced to comply to an oath of secrecy until further notice. Knowing of the nature of Eren's Titan power, the Marley warriors put their attack on hold, believing that he might possibly be the holder of the Coordinate they are searching for.
The damage of the Titan infiltration was temporarily alleviated due to a harpoon net created by the Garrison technical crew, clustering them by the north gate rather than letting them roam free throughout the district. To the north of the district, Captain Weilman interrogated Eren concerning his Titan nature. Despite Eren's insisting that he is human, Captain Weilman caved in to his fears and ordered for the artillery crew to open fire on Eren. With his Titan power, Eren instinctively created a Titan that blocked the cannonball. After leaving his Titan, Armin Arlert pleaded to Captain Weilman in favor of Eren's humanity, but Weilman would not listen to reason until the arrival of Commander Dot Pixis, leader of the southern Garrison forces. After the Commander was briefed on the situation, Armin Arlert proposed a plan to use Eren's Titan power to seal the breach in the southern gate with a boulder within the district. Pixis agreed with Armin's plan, placing his faith in Eren's Titan power.
Sealing the breach
After concluding preparations with the three trainees, Commander Pixis addressed the remaining soldiers of the Garrison and Training Corps awaiting outside of the district. He introduced Eren to the soldiers, claiming he was the first successful experiment in Titan transformation and stating their goal to have Eren's Titan move the boulder in Trost to the breached southern gate to seal it shut. Many soldiers were rightly skeptical and were prepared to abandon the operation. Commander Pixis guaranteed pardon for all deserting soldiers while reminding them of the threat of the Titans that awaited them should they abandon their duty. Many stayed at his words, and Pixis used the opportunity to state the true nature of the operation to reclaim Wall Maria and the disastrous effects of losing another Wall. Once the briefing was complete, Pixis assigned Garrison elite soldiers Ian Dietrich, Rico Brzenska, and Mitabi Jarnach to the Alpha Squad which would accompany Eren en route to the boulder. Meanwhile, Garrison and Training Corps soldiers acted as a lure on the opposite end of the district, gathering the Titans to ensure the safest possible path for the elite soldiers.
After the plan for Eren to seal the breach was made public, Reiner and Bertolt discussed between themselves about their next course of action. However, Marco Bott, a fellow trainee and leader of the 19th Squad, overheard their conversation involving their Titan forms. To prevent their identities from becoming known, Reiner and Bertolt restrained Marco as Annie reluctantly stole his vertical maneuvering equipment, leaving him for dead as a Titan came by, eating Marco alive as the warriors watched with sadness.
Upon reaching the boulder, Eren transformed into Titan form with Mikasa and the Garrison Alpha Squad standing by. However, Eren's Titan form took on a feral state and instead attacked Mikasa before incapacitating itself. Believing the operation to be unsalvageable, Rico fired a red signal flare to announce the mission failure. Rather than signalling a retreat, Commander Pixis allowed for the operation to continue, having faith in the elite soldiers. Armin Arlert, watching the operation from atop Wall Rose, made his way to the site as fast as possible. Meanwhile, the elite soldiers argue among themselves over what would be done concerning Eren's situation. Believing in Eren's potential, Captain Ian Dietrich urged his comrades to defend Eren's Titan at all costs, and the others reluctantly agreed.
As Alpha Squad defended Eren, Armin arrived at the scene. Using a tactic that would injure Eren's human form within the Titan without killing him, Armin was able to communicate with Eren, who was in a dream-like trance. Mikasa left the area to join with Mitabi's squad in the defense of Eren's Titan. Armin succeeded in awakening Eren after reminding him of his dream to see the outside world, and Eren's Titan lifted the boulder. Elsewhere in the city, Rico Brzenska's squad was wiped out in the defense. Upon seeing Eren's Titan making its way with the boulder to the breach, Ian ordered for the defense of Eren's Titan at all costs. As Mikasa joined Ian's squad in Eren's defense, Mitabi's squad took to the ground in order to lure away the Titans, sacrificing their own lives in the process. Eren continued on his way to the breach, reminding himself of the freedom that the outside world would provide and the necessity to fight for his dream. Ian Dietrich was caught and eaten by a Titan as he saved the life of a comrade while Mikasa and Rico killed the Titans near the breach. With the area clear, Eren succeeded in placing the boulder in the breached gate, saving Trost District from destruction. Rico fired off a yellow signal flare to announce the operation's success before joining Mikasa and Armin to retrieve Eren. At the sight of the mission success, Commander Pixis ordered for reinforcements to retrieve Alpha Squad.
Once Eren, slipping into a comatose state, was successfully retrieved from his Titan, the remaining soldiers were cornered between the sealed breach and the Titans. Fortunately, they were saved in time with the arrival of Captain Levi Ackerman, heralding the return of the Survey Corps. Together, the Garrison and the Survey Corps spent the remainder of the afternoon and the following day cooperating to eliminate the remaining Titans in the district. The Garrison used high-explosive projectiles to wipe out the Titans near the Wall as the Survey Corps eliminated those that remained. In the end, the two remaining Titans were captured alive for study.
On the day after the Titans had been eliminated from Trost District, remaining soldiers gathered the corpses of the fallen which would be cremated in order to prevent a secondary disaster. At this time, trainee Jean Kirstein found the corpse of his friend Marco Bott. Meanwhile, the interior at Wall Sheena fell into a state of confusion at the news of a Titan fighting for humanity. Many suspected the news was propaganda from the Royal Government, while others saw Eren as a hero. Tensions rose between the people of Wall Sheena and Wall Rose, and the threat of civil war was being considered by Military Police Brigade Commander Nile Dok.
In the custody of the Survey Corps, the two captured Titans were subjected to various methods of research by Squad Leader Hange Zoë. These experiments included attempts at communication, activity without sunlight, and pain tolerance. Hange had also affectionately named these Titans "Sonny" and "Bean".
Eren woke up from his coma three days after the battle in a prison beneath a courtroom where a military tribunal would be held some days later in order to determine Eren's fate. While there, Erwin Smith and Levi Ackerman informed him of the aftermath of the battle. Afterwards, Erwin informed Eren of his new plan to prioritize the discovery of Grisha Yeager's basement in Shiganshina District, which was believed to hold the secrets of the Titans. With this new plan, Erwin asked Eren of his intentions, and the latter said that he simply wanted to join the Survey Corps to kill Titans. Seemingly impressed, Captain Levi agreed to take responsibility of Eren, prepared to kill him if his Titan could not be controlled, and Eren was accepted into the Survey Corps.