In 850, Connie graduates then participates in the Battle of Trost District. Despite his fear of Titans and his want to please his mother by joining the Military Police Brigade, he eventually joins the Survey Corps.
That same year, a mysterious Titan appears in Wall Rose and turns Ragako inhabitants in mindless Titans. Connie thus makes an unplanned return to his village to make sure the villagers are fine. Once arrived, he worriedly calls out for his family members. Eventually, Connie comes across his old house destroyed by a Titan laying on it. Later on, Connie leaves the village with the Survey Corps but is distracted when he hears the Titan saying welcome back to him. As Reiner calls him, Connie tells him what he just heard and adds that the Titan looks like his mother but Reiner urges him to focus on their mission.
Connie comes back to Ragako and hands Hange Zoë a portrait of his parents. Hange notices the common features between Mrs. Springer and the Titan lying on the Springers' house. Connie recalls the Titan spoke to him and Ymir and Reiner's claim it was not possible. Hange then orders to put ropes instead of the stakes that retained Mrs. Springer and gives Connie the portrait back. Acknowledging all was lasting of his family was his mother and the portrait, Connie cries. This discovery, along with the known information about Titans' physiology and Hange's experiences led her to believe the Titans that appeared in Wall Rose were Ragako inhabitants.
During Marley's attack on Shiganshina, the Survey Corps capture Falco Grice, who had gained the power of the Jaw Titan in the midst of battle. When Jean Kirstein considers feeding Falco to a Titan in the district, Connie insists that Falco should be fed to his mother. Armin Arlert is against feeding Falco to any Titan in fears of prolonging hostility with the Warriors, but Connie decides to kidnap Falco and escape the battlefield as the others are preoccupied with approaching Titans.
At Ragako village, Connie attempts to feed Falco to his mother's Titan, but is foiled when Armin arrives and decides to sacrifice himself, forcing Connie to abandon his plan and save Armin. Connie realizes that even if his mother became human again, she would have suffered if she had inherited the Colossus Titan, lamenting how she told him to become a great soldier, but instead he almost killed a child and one of his friends. Instead, Connie hardens his resolve to save the people of the outside world, in order to do his mother proud.
After Eren Yeager is killed by Mikasa Ackerman, Connie and his mother were able to revert back into human form.