Timeline of the Battle for Earth

This is a timeline of the events slightly before, during, and slightly after the Battle for Earth. The Battle for Earth lasted between October 20 and somewhere around December 3, 2552 or possibly after the later, though notable skirmishes and engagements took place before and after this timeframe. Concurrently with these events, many battles, notably the Battle of Installation 05 and Onyx Conflict, were taking place.

October 20, 2552

 * 1248 hours: Io Station station pings the encroaching Fleet of Sacred Consecration and relays this data to flag headquarters on Cairo Station.
 * At flag headquarters, Fleet Admiral Terrence Hood awards SPARTAN-117, Staff Sergeant Avery Junior Johnson and Captain Jacob Keyes medals for their efforts during the Battle of Installation 04 and subsequent actions, in the case of John-117 and Johnson, now a Sergeant Major. Miranda Keyes received her late father's medal posthumously.
 * 1412 hours: The Covenant Fleet, consisting of 2 s and 13 s exits slipspace just beyond the effective range of Earth's orbital defense platforms Fleet Admiral Joseph Harper prepares all available vessels to engage the Covenant. This order is overruled by Lord Hood, who instead orders the fleet to form a defensive perimeter around the ODP clusters.
 * 1421 hours: The Fleet of Sacred Consecration launches Type-28 Tick boarding crafts toward the orbital defense stations to plant antimatter charges. Two are destroyed in the process: Athens and Malta Stations. Cairo Station is saved from the same fate by the efforts of John-117. The fleet subsequently clears the defensive grid and sends a first wave toward the planet's surface.
 * 1450 hours: John-117 uses the antimatter charge brought aboard Cairo to destroy a the Day of Jubilation, one of the two CAS-class assault carriers in the Covenant Fleet.
 * 1459 hours: The Solemn Penance, the other assault carrier the Prophet of Regret's flagship, blows through the Malta's debris field and jump to New Mombasa, Kenya via slipspace and deploys ground forces. The First Battle of Mombasa begins.
 * 1512 hours: A number of Huragok deployed to New Mombasa are designated tier-one assets by the Office of Naval Intelligence and judged to be exposed to capture or kill. One of these, Asset RD-9743-X, would successfully be acquired by ONI in the hours to come.
 * 1557 hours: A squad of ODSTs, Alpha-Five, confirms the successful procurement of the Conduit, a Forerunner device, from the Covenant pursuant to Operation: WINDOW PANE.
 * 1602 hours: Operation: BUMRUSH is greenlit and ODSTS of the 65th Shock Troops Division are launched from the with the goal of breaching the Solemn Penance.
 * 1603 hours: Solemn Penance makes a sudden slipspace jump only hundreds of meters above the city. The assault carrier is pursued by the, which is in turn followed by two UNSC corvettes and two other frigates. This atmospheric slipspace jump creates a massive overpressure wave and electromagnetic pulse. The ODSTs' drop pods are scattered throughout the city. With Regret gone, Jiralhanae elements in the fleet suddenly turn on their Sangheili compatriots, heralding the Great Schism soon to come.
 * 1606 hours: Gunnery Sergeant Edward Buck exits his drop pod and moves toward Tayari Plaza, the location of Captain Veronica Dare's.
 * 1624 hours: All members of Alpha-Five are designated KIA and the Conduit is determined to be lost.
 * 1636 hours: UNSC Marines launch an attack on Covenant occupiers in Uplift Nature Reserve.
 * 1649 hours: The Mombasa Tether collapses. 38% of New Mombasa is occupied and controlled by the Covenant forces, now without Sangheili, at this time.
 * 1736 hours: Fierce fighting is waged along Kizingo Boulevard.
 * 1810 hours: In cooperation with the NMPD, ODSTs from Alpha-Nine set demolition charges on a bridge leading to ONI Alpha Site, in order to destroy it and slow the Covenant advance in reaching the site.
 * 1852 hours: ONI Alpha Site, the Office of Naval Intelligence's headquarters in the EAP, is destroyed by the UNSC and New Mombasa Police Department in order to deny intelligence to the enemy.
 * 1914 hours: Gunnery Sergeant Buck and Lance Corporal Kojo Agu make their way to the NMPD headquarters for pickup by an NMPD Pelican. The pelican is shot down before it can reach them and a skirmish breaks out between Alpha-Nine and Covenant air units.
 * 2141 hours: Remaining s from the Fleet of Sacred Consecration coalesce over New Mombasa.
 * 2101 hours: Alpha-Nine moves toward Kikowani Station, intending to escape the city through the MagLev train tunnels leading to Old Mombasa.
 * 2206 hours: Lance Corporal J.D., an ODST from Alpha-Nine, awakens after being knocked out after his Single Occupant Exoatmospheric Insertion Vehicle was thrust off-course in the wake of the assault carrier's slipspace jump to careen into the side of a building. He begins to search the city for others from Alpha-Nine.
 * 2215 hours: The excavation of the Excession begins.
 * 2227 hours: The Covenant controls 78% of New Mombasa.
 * 2319 hours: Asset RD-9743-X is sighted and reported by Captain Veronica Dare beneath New Mombasa in its data center.
 * 2324 hours: 94% of New Mombasa is lost to the Covenant.
 * 2359 hours: Gunnery Sergeant Edward Buck rendezvouses with Veronica Dare and Lance Corporal J.D. The Huragok, Asset RD-9743-X, is reported as secured.

October 21, 2552

 * A larger Covenant fleet from the Prophet of Truth arrives above New Mombasa, fully occupying it and its surroundings as they are glassed in efforts to uncover the portal. Alpha-Nine extracts Asset RD-9743-X from the city safely.

October 20 through November 3, 2552

 * Additional Covenant fleets continue to arrive at Earth throughout the invasion of Earth.
 * Spartan-II Blue Team, composed of Frederic-104, Linda-058, and William-043, is deployed on numerous zero-gee operations to repel Covenant warships over Earth. They team also participates in numerous combat missions around the world, including the Battle of Ross Island in Antarctica and an engagement with Covenant forces on the sea floor off of the Yucatan Peninsula.

November 3, 2552

 * 1420 hours: Blue Team is deployed to Cuba, where the Battle of Havana is underway.
 * 1550 hours: The Centennial Orbital Elevator is recaptured from the Covenant but destroyed by the intentional detonation of nuclear devices in close proximity to its upper reaches. Shortly thereafter, the team uses a captured Covenant Destroyer to depart for Onyx.

November 10, 2552

 * The Covenant begins to excavate and occupy built-up positions centered at Free-fire Area OZONE in Arizona, United Republic of North America, while also attempting to activate an artifact there.

November 15, 2552

 * 1725 hours: Avery Johnson interrogates Quick to Adjust, the Huragok recovered from New Mombasa, at the terminus of the Quito Space Tether.

November 17, 2552

 * The Forerunner Dreadnought arrives at Earth. Spartan 117 bails from the ship, landing in a Kenyan jungle. He is recovered by a group of Marines led by Avery Johnson.
 * The Marines, with Spartan-117, make their way to Crow's Nest, where a plan for a counterattack is devised. The base is invaded by the Covenant, and eventually destroyed by the UNSC.
 * The UNSC forces assault the Covenant-held Tsavo Highway, eventually clearing the path to the town of Voi.
 * UNSC Forces neutralize Covenant anti-air defenses in Voi. A battle group from the UNSC Home Fleet initiate the assault on the Forerunner Dreadnought, with no effect. The Portal is activated. Covenant forces flee to Installation 00 through the Portal.
 * Immediately thereafter, a Flood-controlled ship emerges from Slipspace over Voi, crashing to the town. Flood infestation starts spreading around the region. The Sangheili Fleet of Retribution, having given chase, arrives at Earth and glasses Voi as well as its surroundings.
 * A transmission from the UNSC AI Cortana is retrieved from the Flood ship. The Sangheili fleet, along with the UNSC Forward Unto Dawn go through the Portal to the Ark.
 * UNSC forces launch a counteroffensive against the Covenant at free-fire area OZONE.

November 19, 2552

 * 0630 hours: UNSC flagword LUX is declared and UEG emergency broadcast is initiated.
 * 0700 hours: A tactical nuclear deployment is carried out against multiple shielded Covenant positions.

December 3, 2552

 * Operation: MARSH FLASH sees clusters of Jiralhanae leadership eliminated.