Captain (ground forces)
From Halopedia, the Halo wiki
Captain(Marine) is a rank of commissioned officers that is a ranked above a First Lieutenant and below a Major. And is the equivalent to the UNSC Navy's Lieutenant.The ground based military rank of captain is ranked three pay grades lower than a Captain in the UNSC Navy and has no special authority with respect to a ship a marine captain is just another passenger or crew member while on board.
Captains in the Marine Corps generally command and control company-sized units (62 to 190 Soldiers), together with a principal Non-commissioned officer assistant.
