During the Human-Covenant War, the UNSC found itself in an unusual position - being on the defensive in an interstellar war. While the Insurrection was spread across many dozens of star systems, they were largely localised ground-scale conflicts or small-scale space raids. Until 2525, the UNSC had yet to face an enemy that could match it in its element, and in the Covenant they found more than their match. For the first eleven years, humanity was forced to play an exclusively reactive strategy - the Covenant advanced rapidly across hundreds of worlds, giving humanity little room to regroup and make effective counterattacks. The average lifespan of a colony from initial invasion to final abandonment or glassing was usually a matter of days or weeks, compared to the months or, in rare cases,