- Two Treknology sources — Heavy Cruiser Evolution Plans and Ships of the Star Fleet — posit that Republic had been refit from an Archon-class vessel, which may explain why it was extant before the launch of Constitution in the 2240s.
In 2254, James T. Kirk served with his friend Ben Finney aboard the Republic with the rank of ensign. On duty, Finney left a circuit open to the atomic matter piles by accident: an event Kirk reported in his log, causing Finney not to be promoted. (TOS: "Court Martial")
- My Brother's Keeper: Republic has this incident taking place three years earlier, during Kirk's first year at Starfleet Academy.
In 2265, the Republic was involved in a confrontation with Klingon forces in the Argalus Indri system where it defeated three Klingon cruisers. (Ship Recognition Manual, Volume 4: Starships of the Original Series Era)
In 2267, during a wargames exercise, Republic (under command of Commodore Jonathan Keller) fired on USS Lexington with phasers at 1/10th power instead of 1/100th power. Keller was given the choice of court martial or retirement from Starfleet. He chose the latter. (Orion Press: "The Price of Peace")
In 2275, the ship received a refit. (Ship Recognition Manual, Volume 4: Starships of the Original Series Era)
In 2294, the Republic was decommissioned. (Ship Recognition Manual, Volume 4: Starships of the Original Series Era)
The Republic was unable to assist the USS Enterprise-D during the Borg attack on Earth in 2367, or with the task force sent to recover survivors at Wolf 359, as she was undergoing a refit at Utopia Planitia Fleet Yards during this time. (Star Trek: The Prospect Chronicles: "The Burnt Child")
During the USS Cantabrian's battle with Samantha Delaney and her Dark Starship, the Republic was again at Utopia Planitia Fleet Yards for routine maintenance and in no state to assist defending Earth. (Star Trek: The Cantabrian Expeditions: "By All Means Necessary")
- We also assume Elizabeth Singh, during one of her stints teaching at Starfleet Academy, served as an instructor aboard the ship, due to her saying the ship seemed to always be in drydock for one thing or another.
Before the 2270s Fleetwide adoption of the Enterprise delta shield as an insignia, the assignment patch for Republic was a rhombus -- within which would be the Command, Sciences, or Operations symbols in black; or the Medicine symbol in red. (Cover art for TOS novel: My Brother's Keeper trilogy: Republic)