Commander

Common military ranks in English
Navies	Armies	Air forces
Commissioned and Non-commissioned officers
Admiral of the fleet	Marshal or Field marshal	Marshal of the air force
Admiral	General	Air chief marshal
Vice admiral	Lieutenant general	Air marshal
Rear admiral	Major general	Air vice-marshal
Commodore	Brigadier or Brigadier general	Air commodore
Captain	Colonel	Group captain
Commander	Lieutenant colonel	Wing commander
Lieutenant commander	Major or Commandant	Squadron leader
Lieutenant	Captain	Flight lieutenant
Sub-lieutenant	Lieutenant or First lieutenant	Flying officer
Ensign	Second lieutenant	Pilot officer
Midshipman	Officer cadet	Flight cadet
Enlisted grades
Warrant officer or Chief petty officer	Warrant officer or Sergeant major	Warrant officer
Petty officer	Sergeant	Sergeant
Leading seaman	Corporal	Corporal
Seaman	Private	Aircraftman

Commander (French: Commandeur) is a common naval and air force officer rank. Commander is also used as a rank or title in other formal organisations, including several police forces.

Commander is also a generic term for an officer commanding any armed forces unit, for example "platoon commander", "brigade commander" and "squadron commander". In the police, terms such as "borough commander" and "incident commander" are used.

Commander is a rank used in navies but is very rarely used as a rank in armies. The title, originally "master and commander," originated in the 18th century to describe naval officers who commanded ships of war too large to be commanded by a Lieutenant but too small to warrant the assignment of a post-captain and (before about 1770) a sailing-master; the commanding officer served as his own Master. In practice, these were usually unrated sloops-of-war of no more than 20 guns. The Royal Navy shortened "master and commander" to "commander" in 1794; however, the term "master and commander" remained (unofficially) in common parlance for several years. The equivalent American rank master commandant remained in use until changed to commander in 1838. A corresponding rank in some navies is frigate captain. In the 20th and 21st centuries, the rank has been assigned the NATO rank code of OF-4.

Various functions of commanding officers were also styled Commandeur. In the navy of the Dutch Republic, anyone who commanded a ship or a fleet without having an appropriate rank to do so, could be called a Commandeur. This included ad hoc fleet Commanders and acting Captains (Luitenant-Commandeur). In the fleet of the Admiralty of Zealand however, commandeur was a formal rank, the equivalent of Schout-bij-nacht (Rear-Admiral) in the other Dutch admiralties. The Dutch use of the title as a rank lives on in the Royal Netherlands Navy, as the equivalent of Commodore. In the Royal Netherlands Air Force, however, this rank is known by the English spelling of Commodore which is the Dutch equivalent of the British Air Commodore.

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