When the Marleyan government recruited Warriors, they had intended to send Zeke Yeager in as an undercover agent, so they instilled revolutionary ideas in him. Instead, Zeke Yeager reported them to the Marleyan government. Every member of the Eldian Restorationists was injected with Spinal Fluid, turned into Pure Titans, and sent to "paradise," Paradis Island.
Just as the executions were about to end, Commander Gross was about to kick Grisha Yeager off the wall to fight the Titans when Kruger shoved him from the high wall instead.
Kruger then revealed his identity—the "Owl," a Marleyan government insider who had secretly led the Eldian Restorationists. Transforming into a Titan, he destroyed the ship and killed every Marleyan officer present. He demanded that Grisha Yeager inherit his Attack Titan and infiltrate the walls of Paradis Island to reclaim the power of the Founding Titan.
That was Grisha Yeager's life.
Humanity's Victory
An inspiring piece of news spread throughout Within the Walls.
"The Survey Corps has returned." A soldier excitedly reported to his superiors. For every soldier, this was news so joyous it could bring them to tears. It meant that Wall Maria had been reclaimed by humanity—the first such tremendous victory against the Titans in a century, perhaps even longer.
"That's wonderful! We finally won."
"The Survey Corps is incredible!"
"This is the first time we've defeated the Titans."
"Future victories will belong to humanity as well."
"Long live the Survey Corps!"
"Long live humanity!"
Cheering residents could be seen everywhere Within the Walls, celebrating their victory in the most direct way possible.
In Grisha Yeager's final memories, Kruger had once said this.
["The remnants of the royal family left on the continent formed a revolutionary army. My father was once one of them, but he accomplished nothing... He was burned alive.