Trekipedia

Starbase 12

An orbiting command post in the Gamma 400 star system, Starbase 12 was established in 2163 as a test of Starfleet‘s remote construction abilites.^[6] In 2167, at the time that the U.S.S. Essex NCC-173 was lost at planet Mab-Bu VI, Starbase 12 was commanded by Admiral Uttan Narsu.^[5] It remained an excellent location for starship maintenance, as well as containing much of the defense traffic for the inner core of the Federation.^[6] In 2266, the U.S.S. Enterprise NCC-1701 set course for Starbase 12 with the sleeper ship S.S. Botany Bay in tow.^[1] Several months later, it was the closest starbase when the Enterprise visited planet Pollux IV.^[2]

Starbase 12 was evacuated for two days in 2364, apparently because key Starfleet officials were under the control of the blue gill parasites attempting to infiltrate Starfleet Command.^[3] In 2366, the U.S.S. Enterprise NCC-1701-D was scheduled for a week’s worth of maintenance overhaul at Starbase 12, following a mission to Gemaris V.^[4]