In 2276, San Diego was one of over a half-dozen Starfleet vessels, under the command of Commodore Jono Danilov, that intervened in a Romulan conflict that Captain James T. Kirk's USS Enterprise had become involved in, the Battle of Augo. San Diego, along with al-Burak, Speedwell, Hemalat, Lake Ponchartrain, Lake Onondoga, Kilimanjaro, Dauntless and Marathon all departed shortly after the engagement, with the only loss being Danilov's Ortisei. (TOS novel: The Empty Chair)