Operation: RED FLAG was a planned UNSC ONI Section III operation conceived to put an end to the Human-Covenant war. The operation was never executed due to the Fall of Reach and the UNSC's subsequent retreat to Earth.
The operation was to be executed in four phases.
The first phase consisted of the disabling and capture of a Class-Five Covenant vessel. As such vessels only appeared in combat zones to collect Forerunner artifacts, this phase would require the use of a colony located on a planet with a high concentration of such items as bait. It would also require the retrofit of a cruiser, either Halcyon or Marathon-class, to be capable of conducting in-atmosphere operations and surviving the punishing firepower of a Covenant capital ship. For the first phase, Dr. Halsey selected Captain Jacob Keyes to command the newly fitted cruiser UNSC Pillar of Autumn for his exemplary performance during the Battle of Sigma Octanus IV.
The second phase involved the boarding of the captured Covenant vessel by the SPARTAN-IIs, who would then neutralize the onboard defenses and take control of the ship. They, with help from a then-unidentified mission specialist, would then crack the navigation database of the ship and discover the location of the Covenant homeworld.
In the third phase, the Spartans would use the captured Covenant vessel to travel to the Covenant homeworld with the help of Cortana.
The fourth and final phase of the operation involved the infiltration of the Covenant homeworld and the capture of a Covenant Prophet for negotiating purposes. The UNSC hoped that by capturing a Prophet and holding it hostage, they could force the Covenant into agreeing to a truce, ending a war that the UNSC would most certainly have lost.
- Halo: The Fall of Reach (First appearance)
- Halo: Reach
- Dr. Halsey's personal journal (Mentioned only)
- Halo: First Strike