The USS William O. Darby is a Spectre Class Destroyer re-fit. Originally designed in 2297 for exclusive use by Star Fleet Intelligence, and kept under wraps until 2337. The design was re-evaluated and upgraded in the 2370's and approved for use by the Starfleet Special Operations Rangers. 

   The USS William O. Darby is the only Spectre Class ship in operation at this time, and serves as the flagship for the SOR.