New Phoenix Incident

The Battle of Earth was an engagement fought between the UNSC and the Ur-Didact and his Promethean forces in close proximity to Earth in July 2557. The details of the event were covered up by the Office of Naval Intelligence and it was later referred to as the "New Phoenix Incident" in the media.

The battle
Having retrieved the Composer from Ivanoff Station, the Didact set out to attack Earth in his ship, Mantle's Approach. The Didact was unaware, however, that John-117 and Cortana, in a Broadsword fighter, had managed to breach the ship's shields and make the slipspace journey along with it. As the ship emerged near Earth, the UNSC Home Fleet was mustered in Earth's defense; including the, now under the command of Thomas Lasky. Despite this preparation, the fleet's efforts were rendered useless by the advanced technology of the Didact's ship. Hunting for the Composer aboard Mantle's Approach, John-117 and Cortana proceeded to destroy the turrets defending the ship's main weapon, allowing the Infinity to fire upon the Didact's ship to open a hole for the Master Chief's Broadsword. However, the interior defenses made the passage too narrow for the fighter to pass through and caused it to crash, forcing the Chief and Cortana to carry their HAVOK payload to the Composer on foot.

As John-117 and Cortana reached the Composer, the Didact activated the device, killing thousands of people in New Phoenix, a major population center in North America. After fighting past significant opposition from the Prometheans, the Master Chief was able to approach the center structure, only to be ambushed by the Didact. During the struggle, Cortana was able to manipulate the hard light bridge on which the Didact stood, trapping him. This bought the Master Chief enough time to activate a pulse grenade and attack the Didact with it. The resulting explosion pushed the Didact into the slipspace rupture below. As Master Chief activated the HAVOK tactical nuclear weapon, Cortana was able to translocate the Spartan a safe distance away from the blast. The majority of Cortana's processes remained aboard Mantle's Approach, and were presumably destroyed in the nuclear blast. She maintained herself long enough to bid farewell to the Spartan inside a box of hard light she had generated somewhere outside the immediate blast radius. Master Chief was found by a Pelican floating among the debris and was returned to the Infinity.

Aftermath
Following the battle, ONI quarantined New Phoenix and hid the details of the attack from the public, concealing it as a attack by the Covenant remnant. Six months later, however, ONI public relations officer John Sullivan released a statement to the press confirming the Covenant were not responsible for what was now referred to as the "New Phoenix Incident".

Months later, during the Second Battle of Requiem, the UNSC Infinity recovered a Forerunner Durance called the Didact's Gift from the Covenant. The device, said to contain the "soul" of a Promethean Knight, revealed images of New Phoenix during the attack, indicating that the consciousnesses of the composed New Phoenix residents had been transferred back to Requiem and converted into new Prometheans. Adding to the mystery, the images also revealed that another Forerunner artifact had been present in New Phoenix during the attack.

List of appearances

 * Halo 4
 * Spartan Ops
 * Halo: Escalation