The UNSC Myrmidon was a Leonidas-class Heavy Battleship under the command of Commander Sylvie Grey. It served with great distinction throughout the entirety of the Human-Covenant War, surviving numerous engagements with the Covenant Navy, and was critically damaged during the late-war Battle of Manheim. Its crew went on to form a guerrilla warfare campaign against the Covenant on the surface of the planet, which lasted for several months. When peace was made with the Sangheili, the Myrmidon was partially repaired and made the Slipspace jump back to Earth, where it served as a base of operations for the 10th Shock Troops Battalion. It saw service until 2581, when it was officially retired from the fleet.