First Battle

Climbing the Colossus Titan's arm alone, Eren realizes the giant is striking with intent, smashing the cannons and going after the vulnerable district gate, behavior suggesting an intelligence no other Titan displays. Knowing this is a rare shot at the one creature able to destroy the Walls, he goes straight for the nape, but a scalding burst of vapor blinds him, and when it clears the Titan has vanished into thin air, leaving smoke and two huge footprints exactly as it did five years earlier.

A Garrison soldier orders everyone who made contact with the Colossus Titan to report to headquarters, and the response plan spins up. With the Survey Corps away on an expedition, the Garrison must repair the Wall and mount the defense, and the manpower shortage presses the just-graduated trainees straight into combat. Armin frantically lays out the arithmetic: the breach stands eight meters high, and the boulder that could seal it has never even been excavated, so the city will be abandoned and Wall Rose left exposed. Eren steadies him. The trainees are divided into front, middle, and rear guards under warning that fleeing the enemy carries capital punishment. Mikasa, posted to the elite rear guard protecting civilians on account of her abilities, asks Eren to find her if the fighting turns bad; he snaps at her for imposing her own rules in a crisis, and she settles for one request, that he stay alive.

Eren thinks back to classroom lessons on how little humanity understands. Titans lack reproductive organs, show no appetite for anything but humans, and survived a century largely without them, so eating cannot be about nourishment. Their vitality lets them heal from devastating wounds, and only the nape of the neck cannot regenerate, a weak point best struck from vertical maneuvering equipment.

Posted on the rooftops, Eren talks up how quickly they could climb the Survey Corps ladder by proving themselves now, and Thomas proposes a Titan-hunting contest among the trainees. The bravado dies when they meet Titans already pouring past the overwhelmed front guard. A lunging Titan catches Thomas in its mouth and gulps him down; Eren charges after it in a rage and a second Titan leaps up to bite through his leg below the knee. Mina's wire snags and she is slammed unconscious against a building, Mylius and Nac are devoured, and Armin, the only one left untouched, freezes until a Titan simply picks him up. Bleeding and half-conscious, Eren remembers Armin excitedly showing him his grandfather's book about the outside world. Powered by that shared dream, he hauls himself upright, pulls Armin from the Titan's mouth, and throws him clear. As the two reach for each other, the jaws slam shut through Eren's arm, and Armin watches in terror as his friend is swallowed. In the distance, Mikasa turns toward her friends' position with a stab of unease.

Eren attacks the Colossus Titan and concludes it possesses intelligence, moments before it evaporates without a trace.

The 104th's graduates are conscripted into Trost's defense, with Mikasa pulled away to the rear guard while Eren's group deploys as middle guard.

The squad is annihilated: Thomas, Mina, Mylius, and Nac die, and Eren loses a leg, then an arm, and finally is swallowed rescuing Armin from a Titan's mouth.

In Isayama's original vision, this chapter's main events were slated, with alterations, for the second rough-draft chapter of his magazine pitch. The bonus page gives a basic overview of the vertical maneuvering device: secret black-box operating units, twin independently spinning axes feeding steel wire, and a gas-driven fan system fed from compressed cylinders, with the author thanking a scientist friend for the design help.

First Battle ends volume 1 as its fourth chapter, published in Japan in December 2009 during the Wall Sealing arc. The anime covers it in First Battle: The Struggle for Trost, Part 1.