Commander

Commander, in the British navy, one holding rank between that of a lieutenant and that of a post-captain. The rank of "master and commander" was established in the latter half of the 17th century, and its holders have ever since received the courtesy title of captain. Commanders serve either as captains of sloops, corvettes, and vessels not important enough to be commanded by a post-captain, or as chief executive officer under a post-captain in a large ship. Promotion to the rank is by selection, and the full pay is £1 a day.