Commodore, in the royal navy, is a rank intermediate between an admiral and a captain. It is not permanent, but is bestowed for a time on a captain. Usually a commodore commands more ships than one, detached from a fleet on some special service; he hoists at that time a white broad pennant, with a red cross, at the main if a commodore of the first class, at the fore if of the second class. A commodore is privileged to have a commander under him in his ship, in the same way as an admiral is privileged to have a captain. The commodore, in matters of etiquette, ranks with a brigadier-general in the army. When in independent command, a commodore of the first class receives £7, 10s. a day, and a commodore of the second class about £4, 10s.
Until 1862 the title of commodore, without any commission as such, was given in the United States navy to such captains as commanded, or had commanded, a squadron. In 1862 the rank of commodore became a commissioned one. A commodore ranks higher than a captain and lower than a rear-admiral. His rank is assimilated to that of a brigadier-general in the United States army.