Marines were Naval Infantry named after the equivalent forces in Earth's wet Navy history, such as the UK's Royal Marines or the United States Marine Corps. In Manticoran and other Naval practice, they had special training and equipment optimized for operating in Naval operations such as hostile boarding actions or ground side combat. Duties included ship security, boarding actions, and possibly prize crews. Ground based action was also possible, but was limited due to the small numbers of any ship's Marine complement.