Rapid Response Team 59 - the "Fifty-Niners" - were a Starfleet Special Operations unit stationed aboard the USS Monitor. They were involved in several covert actions during the Dominion War. Between 2374 and early 2375, their commander was Lieutenant Therav th'Shan. Lieutenant Chen Yan replaced th'Shan when he became the Acting Chief Tactical Officer. (Eighth Fleet RPG) By the second end of the war, the unit had become integrated more fully with the ship's tactical and security personnel, as the casualties mounted.