Luna (the Moon) has also been colonized and is home to immense planetary defense lasers charged with protecting Terra from invasion. These defenses inflicted savage losses on the invading Traitor Legion fleets of the Warmaster Horus, during the latter stages of the Horus Heresy. Luna served as the greatest shipyard and naval base in the Imperium of Man at the time of the Great Crusade and the Horus Heresy. Luna also gives its name to a common class of Imperial Navy cruiser, the Luna-class.
