Primitive Desire

Gensho-teki Yokkyū (原初的欲求) is the 1st chapter of the 4th volume and the 14th chapter overall of the Attack on Titan manga, written and illustrated by Hajime Isayama.

Overview
While the soldiers are off fighting nearby Titans, Armin manages to wake Eren up from his dormant state in his Titan form. Soon enough, Eren proceeds to continue his mission. The sight of him carrying the boulder gives the Garrison elite soldiers hope, so they plan to continue defending him to ensure humanity's victory. Rico shoots a yellow flare, signifying mission success. Unlike the other soldiers, Mikasa is only keen on leaving as soon as they retrieve Eren. Titans swarm behind them, but a soldier from the Survey Corps comes to their rescue.

Summary
As the soldiers fight the onslaught of Titans drawn to Eren, Armin tries to bring him to his senses, reminding him of his desire to see the outside world. Slowly, Armin is able to bring Eren around in the nick of time. He regenerates him limbs and heaves the stone onto his shoulders, carrying it towards the hole, much to Mikasa and the rest of the escort's amazment. With the mission now on its way to success, the soldiers have a new found energy and vow to protect him even if it costs them their lives

In an attempt to get the Titans' attention off Eren, a small group approaches them on foot. The plan works, but puts them at a disadvantage when they need to escape. Ian orders his team to follow the others so they can hand the target over to them.

Meanwhile, Eren's body feels like it's being crushed under the weight of the boulder. He sees Mikasa and Armin running on the ground and worries that they will fall prey to the Titans, and as Eren struggles with the stone and moves toward the hole, the soldiers are barely able to keep them away. As one Titan manages to get right in front of Armin and Mikasa, another soldier uses his Vertical Maneuvering Equipment and stabs it in the eye, allowing Mikasa time to get behind it and kill it. Armin looks over his shoulder and sees Eren is only a short distance away from the hole now. Eren plugs the hole, but at a great cost. Rico remarks that everyone has died as a result as she fires the yellow flare, marking success.

Atop the wall, Pixis, seeing the flare, orders for reinforcements to immediately be dispatched. With the Titans moving towards them, Rico orders Mikasa to climb up the wall. She replies that she'll only withdraw after Eren is retrieved. Armin, now at the back of Eren's neck, tries to pull him free from the flesh of his Titan form. Mikasa asks about his condition. Armin informs her of his high fever and one part of his body still being stuck. Rico suggests cutting the limb off, but Armin is able to pull him free before she does. As he pulls, they both fall to the ground, nearly at the feet of two Titans. Mikasa rushes to their side, but she won't make it in time. Out of nowhere, a soldier swoops in and dispatches both Titans. When the bodies fall, Eren manages to open his eyes and sees the emblem of the Survey Corps; it's Levi. With the success of the mission, the Survey Corps and the Garrison Engineering Department hurried in and did their part. Wall Rose is sealed and protecting everyone from the Titans again. They delight in humanity's first victory against the Titans, but acknowledge that it came with a high cost.