Opening the Gate

is the 3rd chapter of the 5th volume and the 21st chapter overall of the Attack on Titan manga, written and illustrated by Hajime Isayama.
== Overview ==
After the deaths of Sonny and Bean, all trainees of the 104th Training Corps have their vertical maneuvering equipment inspected. Connie, Armin, and Annie discuss the situation and where they plan to enlist. Later, Eren overhears that no culprit was found among the trainees, and he wonders which of his friends will want to join the Survey Corps. After a brief discussion between Jean and the others, the trainees are called in for their introduction to the Survey Corps.
Standing before the trainees, Erwin Smith tells them of the great losses the Survey Corps has faced in recent years as well as their new advances in knowledge. Erwin gives out the information that the Survey Corps plans to ride to Shiganshina District to locate the basement of Eren's home, causing Armin to wonder. Erwin makes it clear that those who join the Survey Corps are likely to die, and that they must be willing to sacrifice themselves for the good of humanity. Many leave afterward, but those who stay behind are welcomed into the Survey Corps.
One month later in Karanes District, the Survey Corps embarks on the 57th expedition beyond the Walls. The support team keeps a nearby Titan at bay while the rest ride forth to Shiganshina.
== Summary ==
After the killing of Sonny and Bean, six days after the mop-up operation in Trost, all of the trainees are having their vertical maneuvering equipment inspected and the logs checked. Still recovering from the last attack, members of the 104th Training Corps discuss what branch of the military they will join. Armin, Connie, and Annie discuss whether or not they will join the Survey Corps. Connie is frightened at the possibility and asks Annie about her opinion on joining the Military Police Brigade. She tells him that it is his choice to make and not hers. Despite his fears, Armin admits he is joining the Survey Corps. Annie then asks him what he would do if he was told he would have to die and Armin states that if the reasons are good, then he will gladly die. Annie thinks he is weak physically, but also admits he is strong at heart. She states that she is joining the Military Police for a personal reason. Later, Eren hears the news that the inspection has yielded no results, and he wonders which of his friends will join the Survey Corps. Jean, while making it clear that he is nothing like Eren, informs the others that he is also joining the Survey Corps.
The trainees are called to an assembly where Commander Erwin is explaining the situation. He tells them that the Survey Corps is short of personnel. He then brings out Eren and tells them the importance of their new weapon: Eren's Titan powers. With Eren on stage, he tells the trainees the importance it means to mankind and gives a few details of the upcoming mission, even going so far as to reveal the importance of the basement of Eren's home. Reiner and the others are surprised by this information, but Armin begins to suspect the Commander has an agenda in revealing this information so freely. Upon telling the crowd the survival rate of the next mission and the Survey Corps in general, 90% dead in the past four years, he dismisses those that do not wish to join. With most of the people leaving, Jean imagines a possible fate of himself and his friends, while Connie tries to talk himself into becoming a police officer. Sasha tries to convince herself to leave and join another faction. However, her fear prevents her from leaving, and she shares the same sentiments as both Jean and Connie in having to face Titans again. 
When the crowd clears, there are twenty-one people who are inducted into the Survey Corps. Among them Mikasa, Connie, Jean, Armin, Reiner, Sasha and most of the top ten of the 104th Training Corps. Jean is disgusted when he finally realizes that he is now a Scout and not a Military Policeman. Connie does not seem to care anymore, while Sasha is fearful that she might have to face the Titans again. Krista begins to tremble, which disappoints her friend. Bertolt takes one last look as he watches Annie leave to join some other branch.
One month later, the Survey Corps is ready to begin their mission to travel to the Shiganshina District. Due to the closure of the gate in the Trost District, they have to leave from the gate in the Karanes District and travel southward around the Wall. As they depart, they immediately see a Titan, which is intercepted by the support squad. Commander Erwin tells them all to keep advancing on their way to Shiganshina.
== Current Publicly Available Information ==
=== 10. Survey Corps Horses ===
The stable horses used by the Survey Corps are selectively bred to be approximately tall and . They can get on by a simple diet and travel for many hours without complaining. These horses have a mild temperament and rarely panic, even when confronted with Titans. Their top speed is between , and they can maintain a swift gallop. The horses are tenacious, able to maintain a fine speed of even when pulling a carriage. They aren't the Titans' direct goal and are able to outrun the Titans on foot, making them the only method of escape. These horses are extremely valuable. In monetary terms, one is worth an average person's lifetime income.
Author's note: (With thanks to Ukyō Kodachi and Kiyomune Miwa)
== Characters in order of appearance ==
== Navigation ==
de:Kapitel 21
es:Capítulo 21
fr:Chapitre 21
it:L'Apertura del Cancello
ru:Глава 21