Around thirty days after Emergence Day, O'Neill was part of the effort to defend the city of Halvo Bay from a huge Locust assault. O'Neill was stationed at the fortress of Onyx Point on an island near the city. When the Locust attacked the island, O'Neill was attempting to radio the mainland for reinforcements when a sniper shot O'Neill in the back. O'Neill's COG Tag was later recovered by Pvt.Augustus Cole of Kilo Squad.