There's no doubt that Attack on Titan is more Eren's story than anyone else's. Not only is he the face of the show and continues to move the narrative forward, but with the Founding Titan in his possession, it seems like everyone wants to get their hands on him. While Season 4 of the anime will definitely touch on how he's acclimated to a world in which the Titans are no longer his main enemy, he didn't get this far on his own.
Erwin Smith, the former commander of the Survey Corps, lost his life at the hands of the Beast Titan towards the end of Season 3, and while he definitely won't be returning to the battlefield, there were a fair amount of moments where it seemed like he was the main character as all eyes fell upon him. He's played a vital role in the story, and without him, Attack on Titan's plot wouldn't have evolved to the place it is today.
When He Defeated Levi And Forced Him Into The Survey Corps
At the beginning of the special side story No Regrets, Erwin and Levi clashed for a brief few seconds before the commander forced Levi and his companions to join the Scouts.
When he made his debut in the special, he almost looked like a villain, grinning with pleasure at the sight of Levi's instinctive proficiency with ODM gear, which he knew would only aid him in uncovering the secret behind the Titans. Despite not being an Ackerman himself, this scene made it all too clear that Erwin could've had Levi killed if he wanted.
When He Reflected On The Lives Lost Due To His Commands
Part of Erwin's job consisted of sending his soldiers out onto the field with the knowledge that most would die.
He does this with such conviction that it almost seems like he enjoys this, and yet many fans can never forget that iconic scene from Season 3 where he's shown standing atop a mountain of corpses as he reflects on everyone whose lives were lost due to his orders all so he could see what lay in Grisha's basement.
When He Ordered His Men To Advance Despite Having His Arm Bitten Off
In an effort to reclaim Eren from Bertholdt and Reiner after leading them into a group of Titans, Erwin ordered his men to charge into the fray. Not only did he get one of his arms bitten off by a Titan, but even when things looked extremely grim for him, he ordered his men to keep pushing onward as though he weren't staring death in the face.
This made it difficult to focus on the remainder of the operation, as many viewers found themselves wanting to know if the Titan that took Erwin's arm managed to take the rest of him.
When He Put His Coup Into Action
After learning that the true royal family within the Walls was the Reiss family, the Survey Corps set out to debunk the current government and make Historia the rightful ruler of Paradis. Unfortunately, the government within the Walls wasn't too happy about this, and while his skilled subordinates were on the run as outlaws, Erwin himself was sentenced to death.
He wasn't at all fazed by this, since his plan to upstage the government went into motion seconds after his sentence. Erwin's level of poise and confidence in the face of such uncertainty is definitely admirable and showed just how much of a strategist he is even when he's completely unarmed.
When He Surrendered To The Military Police
While many of Erwin's methods don't seem sensical at first, there's always a method to his madness. While it was Armin who figured out that Annie was in fact the Female Titan, Erwin was the one who authorized the plan to capture her in the Stohess District.
When she and Eren waged their final battle in the middle of the city, many civilians lost their lives as a result, and Erwin was arrested due to putting so many people in harm's way. Despite having multiple guns pointed at him and the city collapsing in every direction, Erwin maintained his resolve, accepting punishment for a course of action that he believed to be the best for the people of Paradis.
When He Wounded Bertholdt And Freed Eren
In Attack on Titan, it's not uncommon for characters to lose entire limbs only to jump back in the fight after recovering from such devastating wounds. Of course, these characters are typically Titan Shifters who can not only endure this pain but do so with the knowledge that their bodies will regenerate with time. And yet even after getting his arm bitten off, Erwin played a crucial role in retrieving Eren from Bertholdt and Reiner.
While Armin distracted Bertholdt, Erwin swooped in and took a swing at the Colossal Titan holder, wounding him and detaching Eren from his back. Not only was this a surprise twist, since most probably expected Mikasa or Jean to save Eren, but the look on Erwin's face that seemed to be a combination of pure abhorrence and pain was one that highlighted Erwin's dynamic personality.
When He Gave A Speech To The 104th Training Corps
After the Battle of Trost District, the 104th Training Corps were given a few choices: they could either join the Military Police, Garrison, or the Survey Corps. Though the Survey Corps was in drastic need of fresh bodies, Erwin didn't pull punches with the new recruits.
He told them that many of them would die over the course of the next few years in a spine-chilling speech that apparently was so effective that some of the best graduates of this particular class didn't hesitate to devote their lives to his cause.
When He Led The Charge Against The Beast Titan
When Erwin Smith first addressed the 104th Training Corps, he asked them would they be willing to die if they were ordered to, and yet he did just that when he led most of the Survey Corps on a suicide charge for the Beast Titan in order to make an opening for Levi.
Despite wanting to uncover the secret in Grisha's basement, Erwin knew that he had to risk his own life for the other Survey Corps members to do the same. His speech to spur them to action was nothing short of inspirational, as he filled the Scouts with reassurance that their deaths weren't meaningless in the slightest.
When He Stared Reiner Down
During the Battle of Shiganshina District, Reiner hopped atop the Wall to confront Eren and the others. Erwin, who hadn't yet joined the fray, stood mere feet apart from the Armored Titan, staring him down as though he too had a Titan transformation under his belt.
He showed no ounce of fear despite the fact that Reiner could've easily crushed him and still carried on his mission. The intensity in Erwin's stare is definitely one for the books and honestly had many fans wondering if Erwin would be able to take down Reiner given the opportunity.
When He Refused The Titan Injection On His Deathbed
At the end of the Battle of Shiganshina District, Levi was forced to make an important choice: give the Titan injection to Erwin or Armin. He seemed determined that reviving Erwin from the brink was the best thing he could do for humanity, and yet on his deathbed with his final dying breaths, Erwin managed to smack the injection right out of Levi's hand when the needle was mere inches from his arm.
While this was due to the fact that he was acting out a flashback during his final moments, Levi took this as him refusing the injection, since he already gave up on his dream when he charged for the Beast Titan. Even on his deathbed, Erwin became the center of attention, and as the remnants of the Survey Corps continue the fight without him, it's certain that he'll remain one of the reasons they continue to give it all they've got against their opponents, even if they're fighting on shores that aren't their own.