Battle of Trost District

The Torosuto-ku kōbōsen (トロスト区攻防戦) 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.

Prelude
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 Coordinate 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.

The next morning, the Survey Corps led by Commander Erwin Smith departed on an expedition beyond Wall Rose. In their absence, Trost District was much more susceptible to attack from the Titans.

Early conflict
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 Corporation, attempted to haul an oversized load of goods through the north gate, preventing other citizens from evacuating. As an Abnormal approached the crowd, Trainee 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. 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. When Mikasa left to kill more Titans, 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.