Wall Rose invasion

The Wall Rose invasion was a crisis that began when the Beast Titan turned the Ragako inhabitants into mindless Titans to wander throughout Wall Rose. Eren Yeager was nearly captured by the Colossus and Armored Titans, though through the combined efforts of the military he was retrieved and Wall Rose was cleared of all Titans.

Prelude
In the aftermath of the 57th Expedition Outside the Walls, the Survey Corps was summoned to Mitras in order to hand Eren Yeager over to the Military Police Brigade as per the agreement made during Eren's trial a month prior. However, Commander Erwin Smith devised a secret mission for the Survey Corps to confront and capture Annie Leonhart, a former trainee of the 104th Training Corps suspected of being the Female Titan which sabotaged the 57th Expedition. This operation would commence in Stohess District, Annie's stationing as a recruit in the Military Police and the half-way point between Karanes District and Mitras.

With the identities of the Colossus Titan and the Armored Titan remaining unknown at the time, the Stohess District operation was made known to only the most trusted members of the Survey Corps. In order to isolate Annie from any potential accomplices, a majority of the new recruits from the 104th Training Corps were sent to a remote base in Wall Rose under the watch of Squad Leader Mike Zacharias and his subordinates.

Sighting and evacuation
For reasons unknown, Wall Rose was infiltrated by Zeke Yeager, the warchief of the warriors of Marley. Some time after his infiltration, he made his way to the village of Ragako in the southwestern region of Wall Rose and by some means turned the residents of the village into Titans. These Titans began to wander Wall Rose under Zeke's command as the Beast Titan.

Shortly afterwards in the early morning, Squad Leader Mike Zacharias detected the presence of the Titans in Wall Rose. He quickly sent out his subordinate Thomas to warn the residents of Ehrmich District of the invasion and to deliver a report of the sighting to Commander Erwin Smith in Stohess District. Thomas departed immediately as Mike's comrade Nanaba alerted the recruits of the incident. After Mike and Nanaba briefly assessed the situation, Mike's squad and the recruits set out on horseback to start an evacuation of Wall Rose.

Mike organized the soldiers present into four teams which would spread news of the invasion north, south, east, and westwards. Due to the direction of the incoming Titans, the breach was estimated to lie somewhere between Krolva District in the far west and Trost District to the far south. The south team was assigned the most soldiers in order to assess which area of Wall Rose was breached after spreading information as necessary, starting near to Trost and working westwards. The west team would do the same, investigating Wall Rose starting from Krolva and working southwards. As the teams began to disperse, the nine Titans spotted began running at an erratic pace. Mike chose to break away from the teams in order to act as a decoy, leaving command of the south team to his subordinate Gelgar.

Mike succeeded in slaying five of the nine Titans present before he encountered the Beast Titan, believing it to be an Abnormal. Before he could act, Zeke's Beast Titan caught Mike's horse and hurled it towards him, sending Mike into the mouth of a gluttonous Titan. Before Mike could be eaten, Zeke began to speak with Mike in his Titan form. With Mike too terrified to respond, Zeke chose to steal Mike's vertical maneuvering equipment for inspection, leaving Mike to be devoured alive by his Titans.

Five hours after the sighting, Sasha Blouse on the north team encountered a Titan in a newly established village, much farther north than it was expected the Titans would advance in that time. She succeeded in saving a young girl from a 3-meter Titan, and she afterwards encountered a group of riders led by her father spreading information to the villages of Wall Rose. Sasha remained with her father's riders rather than rejoining with the north team. Seven hours after the sighting, the west team led by Nanaba successfully spread news of the invasion to Wall Rose's western settlements and began their southward ride to search for the breach in Wall Rose.

Eight hours after the sighting, Thomas arrived in Ehrmich District and warned the residents of Wall Sheena of the invasion and the incoming refugees. He immediately continued on his route to Stohess District to warn Commander Erwin and the other participants of the Stohess District raid of the invasion. At this same time, the south team succeeded in alerting Commander Dot Pixis in Trost District of the invasion. The Garrison counter-measures unit led by Captain Hannes was sent out to assist the Survey Corps in locating the breach in Wall Rose. The Garrison 1st Division led by Captain Kitz Weilman was also sent out to establish an eastern line of defense to prevent the spread of the Titans into Wall Rose's eastern villages.

Nine hours after the sighting, the Garrison 1st Division's line of defense was successfully established as Captain Hannes' unit continued to investigate Wall Rose. Elsewhere, Gelgar's south team came across the ruins of Ragako. Connie Springer, a recruit and former resident of the village, frantically began searching for his family. No signs of human life were found, though the south team discovered many strange signs left by Zeke's actions. While there were no corpses or blood to be seen and all the village's horses were still tied in the stables, many houses were broken apart as if something had burst out from the inside. Furthermore, Connie discovered a Titan with underdeveloped limbs lying atop his house with no explanation as to how it got there. Lynne proposed that the citizens had safely evacuated, attempting to lessen Connie's worries, but Gelgar and the others remained suspicious of the scene. Leaving Ragako behind, Gelgar initiated the south team's investigation of Wall Rose. As Connie left the ruins of his house, the Titan spoke to him saying "Welc...ome... home...".

Eleven hours after the sighting, when night had fallen over Wall Rose, the west and south teams met up alongside Wall Rose much to their surprise. Both Gelgar and Nanaba reported that no breach had been located in Wall Rose. A second investigation was proposed, but it was decided that the exhaustion of the recruits would compromise their focus, making an immediate second investigation ineffective. Instead, the south and west teams made their way to Utgard Castle nearby to rest for the night, since the Titans would not be active in the absence of sunlight.

Twelve hours after the sighting, Thomas arrived in Stohess District and warned the leaders of the Survey Corps of the Titan invasion. The participants of the Stohess District mission immediately set out for Ehrmich District to assist in the evacuation of the citizens of Wall Rose. Squad Leader Hange Zoë chose to bring Minister Nick of the Church of the Walls with them due to his apparent knowledge of the Titan within Wall Sheena that was spotted in the aftermath of the Stohess District mission. On the way to Ehrmich, Hange, Armin Arlert, Mikasa Ackerman, and Eren discussed the possibility of using hardening power similar to Annie's to seal the breach in Wall Maria, since the Walls and Annie's crystal were found to be made of the same substance.

Sixteen hours after the sighting, the Survey Corps arrived in Ehrmich. Once Nick had seen firsthand the reality of a Titan invasion, Hange questioned him a second time concerning what he knows. Nick once again refused to speak, but mentioned that Krista Lenz, a new recruit of the Survey Corps, would have the ability to learn and speak the truths about the Walls. With this information, a part of the Stohess participants led by Squad Leader Hange made ready to enter the battlefield. The remaining participants led by Commander Erwin made their way further south to Trost District in order to gather reinforcements from Commander Pixis' Garrison forces as well as the Trost Military Police.

Before departing, Hange received background checks on Annie Leonhart as requested, discovering that she was registered as originating from the same region as Reiner Braun and Bertolt Hoover. The connection between the three was questioned, and Armin recalled that Annie had changed her plan of attack during the 57th Expedition after her encounter with Reiner, realizing that Reiner must have informed her of Eren's true position in the scouting formation. With the possibility of Reiner and Bertolt being Annie's accomplices becoming very likely, all soldiers present agreed to remain quiet about the topic until Reiner and Bertolt could be confronted in an underground location.

Seventeen hours after the sighting, the Stohess District mission participants under Hange's command set a course for Utgard Castle, where a proper view of Wall Rose could be established.

Utgard Castle
Upon arriving at Utgard Castle over eleven hours after the sighting, the south and west teams discovered that the castle had been inhabited by an unknown individual or group. Various supplies had been left in the castle, with labels marked in an unknown writing. The recruits discussed the events of that day, and Connie mentioned the Titan that was found in his house, noting how it resembled his mother. Reiner and Ymir dismissively called his idea stupid to bring the conversation to a halt.

As Ymir searched through the supplies left by the previous inhabitant of the castle, Lynne spotted Titans moving in the moonlight and called for all the soldiers and recruits. As they wondered at the situation, Zeke's Beast Titan passed by the castle heading for Wall Rose. Nanaba ordered the recruits, who lacked vertical maneuvering equipment, to remain in the castle as the soldiers engaged the Titans.

During the combat, the smaller Titans managed to break into the tower. Lynne ordered the recruits to set up barricades to prevent them from infiltrating too far into the tower. Reiner descended the castle as the others gathered barricade supplies, and he was nearly caught and eaten by a Titan until Bertolt saved his life. The other recruits used an antique cannon to block the door, but a smaller Titan came through and nearly killed Connie. Reiner risked his life to send the Titan out of a window, injuring his arm in the process. Outside, the fighting continued as Nanaba and Gelgar killed several Titans while Lynne and Henning went to the top of the castle to check on the recruits. At that moment, Zeke began hurling projectiles at the castle from atop Wall Rose, destroying the stables and killing Lynne and Henning with a boulder thrown at the top of the tower.

Twenty hours after the sighting, after many hours of combat with the Titans, Nanaba and Gelgar had run out of gas in their vertical maneuvering equipment and were killed by the Titans. With all commanding officers absent or deceased, the recruits of the south and west teams were left to fend for themselves. Seeing their hopeless situation, Ymir chose to fulfill a promise made to Krista Lenz a long time ago: when she chooses to publicly reveal her secret, Krista would go by her true name that she had abandoned long ago. As the sun began to rise, Ymir dove into the horde of Titans swarming around the castle and transformed into her Titan form. Ymir's Titan began to slaughter and incapacitate the Titans below, and Reiner and Bertolt recognized Ymir's Titan as the one that ate their comrade Marcel five years ago during the fall of Wall Maria.

Ymir's battle with the Titans began to damage the castle structure, and she chose to be overwhelmed rather than escaping and damaging the castle further. Krista gave encouraging words to Ymir, disregarding the safety of the castle for Ymir's sake. Ymir ascended the castle and told the recruits to mount her Titan's back, and Utgard Castle collapsed on top of the horde of Titans. Ymir attempted to kill the Titans as they began to escape the rubble but was soon overwhelmed, but before the Titans could kill her the Survey Corps participants of the Stohess District mission arrived at Utgard, slaughtering the remaining Titans. Ymir was extracted from her Titan, slipping into a comatose state from her injuries, and Krista revealed to Ymir her true name Historia Reiss.