This is the story of John Stewart, but he's not a member of the Corps. we know him to be in, at this point in time, he's still a member of the Marine Corps. who has been sent into Gotham to help evacuate the city, mainly a football stadium, as they don't want another Katrina scenario. The only problem is, the person who has taken charge in the football stadium is none other than Anarky.
Safe to say, Anarky gives his whole... deal, and his forces don't take kindly to the Marines, and attack them in mass, eventually locking them up with others Anarky has decided to blame. You see, the stadium, like many in big cities, was meant to "revitalize" the neighborhood, but it had to be built over an old neighborhood, so Anarky sees this as the people taking back their land, so to speak.
Through out the whole ordeal, John is the one Marine who is able to keep his head, and not go overboard. He uses his knowledge as an architect to help all the captured people to escape, and fight back against Anarky. He's also the one Marine to not immediately decide to attack civilians, even though they're being lead by Anarky. After they manage to defeat Anarky, despite not being the leader of the squad, John takes control of the situation to help organize the evacuation, leading to a confrontation with his superior officer who threatens a court martial, which John doesn't give a damn about.
When all is said and done, John questions himself for just a second, but decides he did what was right, and the Marines may not be for him anymore. Batman looks on from the shadows, and approves.