The World They Saw

 is the 3rd chapter of the 19th volume and the 77th chapter overall of the Attack on Titan manga, written and illustrated by Hajime Isayama.

Overview
Bertolt Hoover thinks back to when he, Reiner Braun, and Annie Leonhart were trainees during the recovery of Trost District. He and Reiner contemplate what to do about the situation. Thinking they're alone, Reiner lets it slip that they're Titans. Not far from them, Marco Bott overhears some of ther conversation. Reiner assures him it was just a joke, but as Marco leaves to help with the recovery of Trost, he's tackled by Reiner. Shortly after, Annie shows up, and Reiner orders her to remove Marco's gear. Afterwards the three of them leave Marco behind, they stop to watch in horror as he's eaten by a Titan.

Back in the present, the Beast Titan explains to them that Annie is fine. When they're hesitant to believe him, he vaguely threatens Reiner. Reminding them that they have one goal, regain the Coordinate and stop this "cursed history." After receiving conformation that the Survey Corps are on their way, they get into position. Reiner reminds Bertolt to think and act for himself, because he won't be there to tell him what to do.

After the battle has started, Bertolt wonders why Reiner hasn't given the signal. Meanwhile, the scouts believe they have just defeated Reiner, but Connie Springer and Sasha Blouse aren't in the celebrating mood. Armin Arlert is disappointed by the need to kill Reiner, but is interrupted by Mikasa Ackerman when she notices movement. Reiner lets out a roar, and the Beast Titan grabs Bertolt's barrel and throws it at the Walls. Before Hange Zoë could finish giving orders, Armin realizes it's a signal for Bertolt.