Commander Erwin Smith is a supporting character in the anime/manga series Attack on Titan. He is the 13th commander of Survey Corps, known and respected for his foresight, intelligence, and boldness.
Attack on titan when focusing on the military and its soldiers in particular, becoming one and becoming a Survey Corps soldier is certainly a death wish. These are roles that essentially ask their members to sacrifice themselves for the greater good, which will, in turn, save mankind and Commander Erwin is himself responsible for these sacrificial decisions, earning him the title of the devil.
Personality
Erwin Smith’s character in all aspects his strong features, his imposing frame, standing at 6’2. His body language and voice all of this reflect his confidence and power.
He possesses all of the qualities a leader should have, he is brave, intelligent, and decisive, he has an eye for talent as he sought out the abilities of Levi, Armin, and Hange Zoe. But his best attribute is his charisma. He is an inspiration for people around him; he knows how to capture their hearts and can appeal to their emotions. Only Erwin can lead to their deaths by taking advantage of their fears, and their dreams.
As the series has proven the high-ranking military officials only care for themselves but, Erwin seems different than the rest. He deeply cares for the lives of his soldiers and the future of mankind. But he did not hesitate to sacrifice them for the good of mankind. It’s how he became the commander in the first place. Erwin isn’t selfish. A selfish man couldn’t consider himself replaceable.
Backstory of Erwin Smith:

As the series progress, we see where Erwin’s true motivation is born. The commander’s father had a theory He mentioned that the history books, distributed by the government, were full of contradictions. He believed that it was near impossible for humanity not to have passed down oral history. He further adds that the King had altered their memories to make them easy to rule. Erwin has spoken about this possibility to his classmates and military police came to question him and his father didn’t come home that day, he died in some mysterious accident. Erwin has made it his duty to seek the truth of their world. As he says to Levi Ackerman, finding the truth about this world was more important to him than humanity’s victory. The dream he shared with his father kept him going.
Motivation
Family is often the driving force of many characters in this story. Erwin was no different if the dream was the one thing that connected him with his father and he was somehow responsible for his father’s death, this served as a reminder of what he has done as the result of his guilt, so avenging his father is the only way forward. This was his father’s goal and he owes it to him to see it fulfilled.
All of his decision and action revolved around this goal-saving Eren Yaeger and allowing him to join the survey corps even if he lost control because he might be the key to getting to the truth. Erwin was unstoppable in pursuit of knowledge so he isn’t called a devil for nothing.
Erwin Smith :The Final Stand
The commander thinks back to all of the people he led to their deaths, how many people he told to dedicate their lives to humanity, Erwin then saw a he is standing atop all the bodies alone, it highlights the blood on his hand. He felt the loss of every single member, it was his responsibility he was not Levi or Pyxis.

Erwin alone had to climb the pile of corpses to achieve a dream and in that time, he was been lying to himself and his comrades. Saying that it has been for humanity, when its hasn’t been.
Levi Ackerman when getting attacked by the Beast titan made a decision for him, “Give up on your dreams and die for us”. Erwin finally given the okay to let go of his dream and Erwin thanked him. Erwin then made of most inspiring speech, he told what recruits wanted to hear.