The Galactic Alliance Marine Corps became its own branch of the Alliance Defense Force after the liberation of Coruscant and the formation of a Galactic Alliance. It remains one of the most highly trained and specialized units, with its roots in the Alliance Special Forces. As the former New Repulic grew, the defense of member worlds took higher priority than assault. The newly-fashioned Alliance Defense Force needed a mobile element that could be staffed aboard the vessels of the Alliance Defense Force Fleet.