For all of its tactical and strategic ingenuity, the Covenant has always held the advantage in its genocidal war against humanity in two key areas - technological superiority, and numerical superiority. On the ground, the UNSC Army, Air Force and Marine Corps can offset the sheer numbers the Covenant can field against them, and have occasionally been able to rally would-be defeats into unlikely but important victories. But in the battle for orbital supremacy, the UNSC Navy has been unable to hold the Covenant off for more than a few weeks at most, and the UNSC's only available tactic has been to evacuate a planets populace as rapidly as possible before the orbital perimeter falls apart and the orbital bombardment commences. Even then, it is a rare case when a colony has been fully evacuate