The commanding officer of a starship, starbase, or installation is the highest authority of a particular assignment. He or she is responsible for the actions and safety of the crew under his or her command.
In Starfleet, the commanding officer of an installation or starship is the highest-ranking officer and ultimate authority for crew assigned to that particular posting. Starfleet Command provides a general outline of the minimum rank an officer can hold as commanding officer for a specific vessel according to the vessel's size and armament.
Hull Class Minimum Rank Dreadnought Captain Battleship Captain Battlecruiser Captain Carrier Captain Escort Carrier Captain Heavy Cruiser Captain Supermax Freighter Captain Superman Transport Captain Tactical Cruiser Commander Light Cruiser Commander Heavy Freighter Commander Heavy Transport Commander Medium Destroyer Lieutenant Commander Destroyer Lieutenant Commander Frigate Lieutenant Commander Medium Freighter Lieutenant Commander Medical Corvette Lieutenant Corvette Lieutenant Transport Lieutenant Auxiliary Starship Lieutenant (JG)
Bajoran Defense Force
Hull Class Minimum Rank Dreadnought Captain Battleship Captain Battlecruiser Captain Carrier Captain Heavy Cruiser Captain Escort Carrier Commander Tactical Cruiser Commander Light Cruiser Commander Medium Destroyer Commander Destroyer Commander Fast Destroyer Lieutenant-Commander Frigate Lieutenant-Commander Medical Corvette Lieutenant-Commander Corvette Lieutenant-Commander Fast Frigate Lieutenant Auxiliary Starship Sublieutenant Heavy Freighter Sublieutenant Medium Freighter Warrant Officer Light Freighter Warrant Officer Transport Warrant Officer
Unit Size Minimum Rank Division (10,000+) Brigadier Regiment (2,000+) Colonel Battalion (300+) Major Company (80+) Lieutenant Platoon (15+) Second Lieutenant Squad (8+) Master Corporal Fireteam (3+) Corporal