The Garrison Regiment is the largest military branch within the Walls, responsible for defending the three concentric Walls and the cities within them. Unlike the Survey Corps that ventures outside, the Garrison stays within the Walls to man the cannons, maintain fortifications, and ensure public order. They are stationed across multiple districts including Trost, Karanes, and Yarckel, with each section assigned to defend specific Wall segments. The Garrison forces are divided into standing divisions that patrol the Walls 24 hours a day, ready to respond to any Titan breach or emergency within human territory.
The Garrison Regiment serves as the first line of defense when Titans breach the Walls, deploying cannon fire and coordinated ground defense to contain breaches. During the Fall of Wall Maria, the Garrison was overwhelmed by the Colossal and Armored Titans' coordinated attack, suffering massive casualties and organizational collapse. In peacetime, they manage Wall maintenance, regulate immigration between Wall territories, and enforce quarantines. After the coup d'etat that overthrew the monarchy, the Garrison reorganized under Commander Dot Pixis's leadership to support the Survey Corps' operations, eventually participating in the defense of Paradis against the Marleyan invasion force.
Dot Pixis was the Commander of the Garrison Southern Division, a brilliant military strategist with distinctive red hair and a perpetual drinking habit. He was among the first to recognize Eren's potential value to the military and proposed using the Coordinate ability against the Titans. Hannes was a veteran Garrison soldier who knew Eren, Mikasa, and Armin since childhood, having been one of the soldiers who rescued Mikasa during the attack on Shiganshina. Kitz Weilman was a Garrison officer stationed in Trost who initially ordered Eren's execution after his Titan transformation, later accepting the strategic value of keeping Eren alive.