The 104th Training Corps represents far more than a simple boot camp in the world of Attack on Titan. It is the crucible where raw teenagers are shaped into soldiers, and where the tangled dynamics of military hierarchy and deep personal friendships first take root. Within the walls of the training compound, the series lays down its foundational exploration of how human beings cope with fear, ambition, and the constant threat of annihilation. The relationships forged here—and the rigid command structure that oversees them—echo through every major arc of the story. To understand the full weight of the betrayal at Trost, the revelations of the Warriors, and the eventual division of the Survey Corps, you must first understand what happened inside the 104th.

The Formation and Purpose of the 104th Training Corps

After the fall of Wall Maria in the year 845, humanity retreated behind Wall Rose, and the military faced a critical shortage of capable soldiers. In response, the Training Corps system was expanded, and the 104th Southern Division was formed. Its mission was straightforward: take promising young recruits from the refugee camps and interior districts, break them down, and rebuild them as soldiers who could one day join the Garrison, the Military Police, or the Survey Corps. The cadets came from disparate backgrounds—farmers, merchants, city dwellers, and children of fallen soldiers—all united by the shared reality that the Titans might one day breach their new home as well.

The training grounds, nestled in a forested region south of Wall Rose, offered a controlled environment to simulate the terror of combat without the immediate risk of being eaten. Here, recruits ranging from age twelve to fifteen would spend three years learning everything from Titan biology to ODM gear operation. The class of the 104th drew particular attention because it contained an unusual concentration of talent and secrecy. Among its ranks were future members of the Survey Corps’ elite, two Titan shifters hiding in plain sight, and the secret heir to the true royal family. This convergence of fate was no accident; the chaos of Wall Maria’s fall funneled desperate souls into the same place, and the corps became a microcosm of the entire conflict. For a visual and episode-by-episode breakdown of how the class was introduced, you can refer to the official character guides on Crunchyroll’s Attack on Titan series page, which chronicles the early recruitment arcs.

The Rigorous Training Regimen

Daily life in the 104th was a punishing grind. Under the iron fist of instructor Keith Shadis, cadets rose before dawn and pushed their bodies to the limit. The program combined long-distance running, hand-to-hand combat, sword drills, and most critically, training with the omni-directional mobility gear. Maintaining balance while suspended from harnesses required a unique sense of spatial awareness and core strength, and not everyone adapted equally. Early failures were common and humiliating—Shadis made sure of that, singling out weakness with his infamous psychological breakdowns, like when he publicly exposed Eren’s inability to stay upright during the initial balance test.

But the physical torment had a dual purpose. First, it filtered out those who would only be a liability on the battlefield. Second, it created a shared experience of suffering that inadvertently bound the cadets together. When recruits collapsed from exhaustion, they often helped one another to their feet even as Shadis barked at them. The training ground thus doubled as a laboratory for human resilience. According to the detailed lore page on the 104th Training Corps fan wiki, the grading system was weighted heavily toward practical ODM skill and tactical decision-making, which directly shaped the final rankings. Those who refused to help struggling peers fell behind socially, while those who offered support—like Armin sharing his Titan knowledge—created bonds that transcended the competition.

Psychological Conditioning and the Philosophy of Sacrifice

Beyond physical drills, Shadis ingrained a harsh philosophy: your life belongs to the state, and your death must have meaning. Recruits were taught to view themselves as replaceable assets in the fight for humanity’s existence. This indoctrination was necessary to steel them against the paralyzing terror of a Titan’s approach. Yet it also created a dangerous tension. How could you form genuine friendships if you expected your comrades to die tomorrow? The answer emerged organically: the cadets learned to compartmentalize. They practiced killing with brutal efficiency during daytime sparring sessions, then sat around the mess hall at night, laughing and stealing bread from Sasha. That duality—the cold duty of a soldier and the warm heart of a friend—became the signature psychological burden of the 104th, and it haunted many of them long after graduation.

Hierarchy: Competition and Command

Within the walls of the training compound, hierarchy was both explicit and unspoken. The formal structure placed instructors at the top, followed by the graduating class rankings. The top ten graduates earned the right to choose their preferred military branch, a prize that dangled the golden ticket of the Military Police—a life of safety inside Wall Sina—before every cadet. This system deliberately pitted individuals against one another. Eren Yeager, driven by a burning desire to join the Survey Corps and see the outside world, found himself clashing with Jean Kirstein, who openly admitted he wanted only a cushy post in the interior. Their friction was the purest expression of how the ranking system separated ambition from idealism.

The Role of Keith Shadis as a Hierarchical Enforcer

Keith Shadis embodied the hierarchical power of the military state. He was not merely a trainer but a judge, a father figure, and a prophet of doom all at once. His infamous evaluations broke spirits and rebuilt them according to the military’s needs. When he singled out Eren as a potential titan-slaying prodigy, then dismissed him as a failure moments later, he illustrated the fickle nature of rank. A cadet’s worth could change in an instant based on a single performance. This environment forced recruits to constantly reevaluate their place in the pecking order. Mikasa Ackerman, who routinely dominated every physical test, was placed on an unreachable pedestal, while Armin Arlert, whose strategic mind was unmatched, found himself ranked closer to the bottom because of his lack of physical prowess. The hierarchy was an incomplete measure of human value, and the series never lets us forget it.

Ranking also influenced informal social dynamics. Those in the top tier, like Reiner Braun and Bertholdt Hoover, commanded natural respect from their peers. Lower-ranked cadets like Connie Springer often deferred to them. Yet this external shell of hierarchy masked a deeper truth: some of the highest-ranked cadets were the enemy. The Warriors—Reiner, Bertholdt, and Annie Leonhart—had deliberately climbed the ranks to gain strategic access. They understood the system and exploited it. This betrayal of trust, when eventually revealed, highlighted how the rigid structure of the corps could be weaponized by those with hidden agendas.

Friendship as a Survival Mechanism

If hierarchy provided the skeleton of the 104th, friendship provided its beating heart. The central trio of Eren, Mikasa, and Armin is rightly celebrated as one of the most powerful bonds in anime. Their connection predated the corps: Eren rescued Mikasa from traffickers, and Armin defended Eren from bullies with nothing but his words. Within the training corps, that bond deepened into something life-sustaining. Mikasa’s protective instincts, often criticized by Eren as overbearing, were her way of preserving the only family she had left. Armin’s quiet encouragement during Shadis’s brutal critiques gave Eren the psychological strength to persevere. Without that emotional scaffolding, Eren’s eventual transformation into the Attack Titan might have been a tragedy of isolation rather than a spark of hope.

Friendships Beyond the Core Trio

The 104th was rich with other meaningful connections. Jean and Marco Bott shared a defining friendship that shattered Jean’s selfish worldview. Marco’s death during the Battle of Trost, and the revelation that it was caused by the Warriors’ betrayal, became the cornerstone of Jean’s moral evolution. Their late-night conversations about leadership and fear showed that friendship in the corps wasn’t just about comfort—it was a catalyst for identity change. Similarly, the comic duo of Sasha Blouse and Connie Springer provided levity but also demonstrated unwavering loyalty. When Sasha stole from the mess hall, the group covered for her, affirming that they were more than soldiers; they were a makeshift family.

Ymir and Historia Reiss (then known as Krista Lenz) formed a bond shrouded in secrecy. Ymir’s knowledge of Historia’s true identity and her willingness to sacrifice everything for her revealed that love could exist even amidst the lies. Their relationship challenged the military’s emphasis on self-sacrifice for the sake of humanity by proposing a different priority: sacrifice for the sake of a single person. That idea resonated deeply when Ymir chose to leave with Reiner and Bertholdt, a decision that still divides fans but underscores the complex interplay between friendship and duty that the 104th fostered.

Conflict, Rivalry, and Reconciliation

Conflict within the corps was as common as camaraderie, and it often strengthened the group. Eren and Jean’s rivalry was visceral—fistfights in the mess hall, shouting matches during drills—but it was rooted in philosophical disagreement. Eren believed in fighting no matter the cost; Jean believed in surviving by any means necessary. Their reconciliation began with mutual respect earned through shared trials. After watching Eren’s reckless courage during an ODM exercise, Jean admitted privately that he admired him, even if he’d never say it aloud. That uneasy respect later transformed into genuine trust when they fought side by side against the Female Titan. The series used these small moments of conflict resolution to show that hierarchy and friendship are not opposites but forces that can temper each other.

The Interplay of Hierarchy and Bonding

The genius of the 104th Training Corps narrative lies in how it refuses to let hierarchy and friendship exist in separate spheres. The ranking system constantly threatened to pull friends apart, yet the emotional bonds pulled them back together. When the top ten cadets had the chance to choose their branch, Mikasa and Armin could have easily opted for the Military Police, leveraging their ranks for safety. Instead, both followed Eren into the Survey Corps, an act of personal loyalty that defied the structural incentives of the army. Similarly, Jean surprised everyone—including himself—by joining the Survey Corps after Marco’s death, proving that friendship could override the careerist logic of the hierarchy.

This tension also played out in the daily enforcement of discipline. Shadis punished collective infractions by having the entire corps run laps, deliberately using group punishment to foster unit cohesion. The method was harsh, but it worked: cadets learned that their individual actions affected everyone, and they began policing each other. This created a hybrid culture where the formal chain of command was reinforced by peer pressure born out of friendship. By the time the Colossal Titan breached Trost, the 104th functioned as a single organism, capable of improvised teamwork that no drill instructor could have scripted. The scene where the remaining cadets rally to protect Eren’s Titan form from attacking Titans is a direct payoff of this dual dynamic.

Pivotal Moments That Shaped the Corps

Several events during the training period itself—and immediately after—became turning points that revealed the true character of the 104th. The night exercise in the forest, where the recruits had to set up a camp and share watch duties, exposed anxieties that morning drills concealed. It was during such moments that Reiner’s big-brother persona and Bertholdt’s quiet nervousness were on full display, painting them as reliable teammates rather than hidden enemies. In retrospect, these scenes are laden with dramatic irony, and they show how the training corps was itself a stage for performance, where Titan shifters and ordinary humans alike played their roles.

The Impact of the Female Titan Arc on 104th Dynamics

Although the Female Titan arc occurs after graduation, its roots are firmly in the 104th. Annie’s exposure as a traitor shattered the group’s trust in a way that no training exercise ever could. Reiner and Bertholdt’s subsequent betrayal sealed the wound. The friendships formed during those three years suddenly seemed naive, even dangerous. Yet those same bonds are what enabled the Survey Corps to eventually break through the Warriors’ armor. Armin’s ability to deduce Annie’s identity relied on his intimate knowledge of her habits and demeanor, knowledge gained through friendship. Similarly, Eren’s rage at Reiner’s betrayal was so explosive precisely because he had looked up to him as a big brother. The 104th had inadvertently created a network of empathy so deep that it could be weaponized for intelligence and manipulation, as when Armin manipulated Bertholdt’s affection for Annie during the Return to Shiganshina arc. This complex legacy is explored in many fan analyses, including thoughtful pieces on Polygon’s examination of Attack on Titan’s core relationships, which discuss how early bonds laid the groundwork for later decisions.

Legacy of the 104th Training Corps

The 104th Training Corps ceased to exist as a formal unit after graduation, but its influence never faded. The graduates scattered across the three military branches, each carrying the lessons—and the scars—of their time together. Members of the Survey Corps such as Eren, Mikasa, Armin, Jean, Sasha, and Connie formed the backbone of the Special Operations Squad and later the main assault force. Their shared history allowed them to communicate with minimal words, turning them into an elite team that even veterans like Levi acknowledged. The internal hierarchies established during training, such as Mikasa’s physical dominance and Armin’s strategic authority, were adapted rather than discarded, proving that the corps’ structure had real adaptive value.

Beyond the practical battlefield advantages, the 104th’s legacy is thematic. The entire series questions whether humanity should be ruled by a rigid military state or by the chaotic freedom of individual choice. The training corps, in miniature, tested both. It showed that authority without compassion creates resentment, and friendship without discipline breeds chaos. The survivors who made it to the final confrontation against the Founding Titan carried within them the memory of every fallen comrade—Marco, Thomas, Mina, and countless others—and that memory fueled their determination to create a world where such sacrifice would no longer be necessary. The hierarchy had taught them to follow orders; their friendships taught them what orders should never be followed.

Conclusion: A Microcosm of the Human Struggle

The 104th Training Corps is far more than a setting; it is the thematic seedbed for the entirety of Attack on Titan. In its barracks, mess halls, and training forests, the series perfected its meditation on how we balance the need for structure with the craving for connection. The hierarchy pushed cadets to compete and climb, while friendship pulled them back into mutual aid. Neither force was pure, and neither was sufficient on its own. Eren’s eventual radicalization can even be traced back to the contradictions he absorbed during those three years: the world demanded sacrifice but gave him people worth sacrificing for. That tension never resolved, but the 104th showed that within overwhelming darkness, the smallest unit of resistance is a group of friends who refuse to leave one another behind. Their story remains a powerful reminder that even in a world full of Titans, the bonds we form in our training days can shape the fate of nations.