First Battle: The Struggle for Trost, Part 1 (初陣 ―トロスト区攻防戦①― Uijin -Torosuto-ku Kōbōsen (1)-?) is the 5th episode of the 1st season and the 5th episode overall of the Attack on Titan anime, produced by Wit Studio and Production I.G.
Eren's fight with the Colossal Titan comes to an abrupt halt when the creature vanishes without a trace. The cadets are entrusted with the defense of the city, causing many to panic or lose hope, and Mikasa worries for Eren's life. When the battle begins, Eren's squad is quickly decimated by the invading Titans. Armin is saved from the brink of death by Eren, but Eren is eaten in his place.
While Eren is running on top of the Wall, the Colossal Titan charges at him, destroying the upper portion of it. Eren sees that the Titan aimed for the cannons, realizing that the gate being destroyed is not a coincidence either - the Colossal Titan is intelligent. With his omni-directional mobility gear, Eren rushes towards his opponent, while dodging the Titan's slow attack. However, just as Eren is about to strike a fatal blow, the Colossal Titan releases a huge amount hot steam, slowing Eren down. Eren attempts to approach his target one more time, but as he tries to slash with his blades, he realizes there is no contact - the Colossal Titan has disappeared.
The soldiers quickly begin their attempts at dealing with the Titans, not wanting to repeat the hell from five years ago. While the civilians continue their evacuation, the new recruits are preparing to head into action. Armin panics, claiming that the Titans can annihilate them at any time. Elsewhere, Dot Pyxis plays chess with Lord Wald at his residence. Wald complains that in spite of playing him every month, Pyxis still fails to improve. At that moment, a soldier barges into the room, announcing that the Colossal Titan destroyed the gate at Trost District. Pyxis stands up, taking Wald's bottle of booze. Revealing that he intends to go to Trost, Wald tries to stop him, claiming that his duty is to protect him and his property. However, that has no effect as Pyxis immediately leaves.
At Trost, Woerman gives orders to the cadets, dividing them into individual groups. After telling them the objective - to protect the evacuating civilians - he dismisses them. Most of the soldiers are in a state of panic or despair just as Jean walks through the area, annoyed, knowing that he was supposed to go to the interior next day. He bumps into Eren, which enrages him even more. However, Eren makes him remember how they survived their training, claiming that they'll come out of this alive as well. As Jean leaves, Eren is approached by Mikasa who tells him to look for her in case of trouble. However, they are interrupted by Ian Dietrich who tells Mikasa that she is been specially assigned to the rear squad. Mikasa tries to argue, however, Eren snaps at her, saying that nobody cares about what she wants as it is mankind that is in danger right now. As they are about to part, Mikasa asks Eren not to die.
Some time later, Eren recalls his time as a member of the 104th Cadet Corps. In a class, an instructor is reading a book about Titans, revealing information about them. Eren is seen shocked to hear about their regeneration, them not needing to eat or their unknown means of reproduction. When the instructor is questioned whether the Titans are invulnerable, he reveals their weak spot - the nape of their neck and the two blades used to slice through it. Back in the present, Eren and Armin are standing by, waiting for orders. Eren claims that this is their chance as doing well in the operation before even joining the Scout Regiment will surely lead into their promotion. The rest of his squad is also eager to prove themselves. At that moment, they are ordered to assist the front guards. Running through the city, they find out that the Titans are already inside. Suddenly, they are targeted by an Abnormal Titan who jumps at them. Thinking they have evaded it, the group realizes that it is Thomas being held in the Titan's mouth. Before he can react, the Titan devours him, much to the horror of his teammates.
An enraged Eren then rushes forward with his omni-directional mobility gear in order to slay that Titan, but is intercepted by another Titan who bites off his leg, causing him to fall down. His teammates are in shock just as more Titans appear, killing them one after another, much to the horror of Armin, who starts exhibiting the thousand-yard stare. He is then approached by another Titan who puts him into his mouth. As half-conscious Eren sees all of this, he recalls part of his childhood living in Shiganshina District. At that time, Armin comes looking for him, carrying a book containing the information about the outside world with himself. Eren's interest grows as Armin reveals many secrets of the outside world. Just as Armin wishes to go outside one day like his parents will soon, Eren, now in present, stands up and instantly grabs Armin's hand, throwing him out of the Titan's mouth. Using a blade as a way to keep the Titan's mouth open, Eren states that he will go to the outside world. Armin urges him to hurry, but it is too late, as the Titan shuts its mouth, biting Eren's arm off while devouring the rest of the body. Elsewhere, Mikasa looks towards Eren's direction, sensing that something is off.
Currently Publicly Available Information
Prior to the ODM Gear, cannons were humanity's primary anti-Titan weapon. In order to make up for their lack of mobility, the cannons were placed on the Walls, and defensive improvements were made to the Walls (for clarity) as well.
Grapeshot: Low lethality but effective at stopping Titan movement.
Shells: Deal a large amount of damage, but their extremely low accuracy makes it very difficult to aim and hit a target.