Admiral is the highest military rank in most navies. It also may refer to the highest group of ranks (i.e., "general officer", sometimes interchanged with the naval term "flag officer"). Some South American navies, among others, have only one rank of admiral.
While some navies have a higher grade of "admiral of the fleet" or "fleet admiral", they are no longer used in Western navies. In the U.S. system, however, "admiral" it is one grade higher than NATO; a U.S. admiral is officer grade O-10, not O-9.
In modern militaries, typical command assignments at this level would be a theater command (e.g., U.S. Unified Combatant Command), or a very high staff position, such as senior officer of a service or Chairman of the Joint Chiefs of Staff Typical modern assignments for an admiral not commanding operational fores include, in the U.S., the Director of National Intelligence, a major support or training/readiness organization such as the Pacific Fleet (above the numbered operational fleets), or Chief of Naval Operations.
Lower flag grades
While there are national differences, there are usually three grades of admiral, possibly with a higher rank and a lower rank in wartime.
- Fleet Admiral, Admiral of the fleet; rarely used
- Vice admiral
- Rear admiral
- Commodore (some navies, especially the U.S., treat "commodore" as a temporary rank, and have "Rear Admirals of the Upper Half" and "Rear Admirals of the Lower Half", who wear the same insignia as a rear admiral. Periodically, in the U.S., the other military services scream loudly enough that the "one-star" commodore rank is reinstituted. When that happens, a naval officer of commodore grade no longer wears insignia that appears higher than another one-star of equivalent seniority).
Many countries follow U.S. or British usages. Both wear sleeve insignia of one broad and three full rings. As shoulder or collar insignia, U.S. admirals wear four stars, while the Commonwealth uses a crown, crossed baton & sword and three stars.
- NATO codes for grades of military personnel: Agreed English texts, 1992, NATO Standardization Agreement (STANAG) 2116