After he was healed to full health again he helped train new recruits for the UNSC. Years after he had trained a fair share of recruits he backed away from the job and switched to building ships in the UNSC shipyards. During the battle Marcus went into shock and almost died from it. He lost his memory of things that happened recently and long ago. While everyone during the battle thought only of themselves, Marcus received no medical attention and was forgotten and left to die. No one knew who he was and what he previously did.