The Ariel Campaign was a minor engagement of the Human-Covenant War, taking place January 8, 2552. While the initial Covenant invasion of Ariel was unopposed, UNSC forces deployed in Operation: FIRESIDE inflicted tremendous casualties on alien personnel. The UNSC successfully denied the Covenant access to a potentially game-changing artifact as well, resulting in a surprising Covenant withdrawal. Much of the population of Ariel was subsequently evacuated, though a small number remained behind to continue excavations.