<P> Commander (often abbreviated Cdr) is a senior officer rank of the Royal Navy of the United Kingdom . It is immediately junior to captain and immediately senior to the rank of lieutenant commander . Officers holding the junior rank of lieutenant commander are not considered to be commanders . </P> <P> The title (originally' master and commander') originated in around 1670 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, or (before about 1770) a sailing - master who was in charge of a ship's navigation . These ships were usually unrated sloops - of - war of no more than 20 guns, fireships, hospital ships and store ships . The commanding officer of this type of ship was responsible for both sailing and fighting the ship and was thus its' master and commander' . </P>

What is a commander in the royal navy
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