The Fleet of Sacred Consecration was the Covenant task force under the command of the Prophet of Regret. Originally composed of thirteen CCS-class battlecruisers and two CAS-class Assault Carriers, the fleet suffered tremendous losses when it accidentally stumbled upon the heavily-defended planet Earth.
After the Prophet of Regret accidentally discovered the location of the Ark Portal in his search for relics, he quickly conjured a small excavation fleet to uncover it. He was unaware that the relic he sought after was located on Earth. His significantly outnumbered and out-classed fleet was quickly attacked by a fleet of eight Marathon-class heavy cruisers and sixty-seven frigates under the command of Fleet Admiral Harper.
The Covenant Fleet then deployed dozens of boarding craft at the orbital defense platforms defending the planet, in hopes of destroying a cluster with antimatter charges. They managed to destroy two orbital stations; the Athens and Malta station, clearing a path for Regret's flagship, the Solemn Penance to reach Earth.
Meanwhile, the UNSC ships split into echelons, where one group of ships attacked the carriers and a second covered the cruisers. The combined firepower of Fleet Admiral Harper's fleet ensured the rapid destruction of many of Regret's ships, in spite of the numerous losses the human fleet was sustaining. The Fleet's second carrier, Day of Jubilation, stayed in orbit and disabled at least one Marathon-class cruiser with an Energy Projector. At some point during the battle its shields were destroyed by the Home Fleet's concentrated assault, allowing a pair of Longsword fighters to punch a hole into the carrier's hull, thus exposing the hollow center housing the ship's reactor core. John-117 managed to disable the Covenant bomb meant for Cairo and threw himself and the device into vacuum, activating it next to the core and propelling himself to safety, thus destroying the carrier.
After UNSC forces in New Mombasa began to push Covenant troops back to Regret's landing zone, Regret was informed of the location of Halo Installation 05, and proceeded with an in-atmosphere Slipspace jump, with UNSC ships UNSC In Amber Clad, UNSC Dusk, UNSC Coral Sea, UNSC Paris and UNSC Redoubtable following. At least one other Covenant ship escaped the battle, the cruiser Pious Inquisitor, which would eventually become part of the Fleet of Retribution.
The battle in Earth orbit destroyed the vast majority of Regret's fleet, whose loss was compensated for by the arrival of Truth's fleet, which proceeded to invade Earth.