Towards the end of the
Mexican–American War, Marvin left his Boston law practice for the West Coast. He was with the
Quartermaster Corps of the
United States Army. He left the military in 1849, becoming editor of the
Sonora Herald, and settling in
Tuolumne County. Known locally as "Judge Marvin", he became a prominent citizen and part-time official. Marvin laid out the settlement of Empire City on the
Tuolumne River in
Stanislaus County, California (at that time in
Tuolumne County). It became the county seat of the new Stanislaus County in 1854, and an army supply center. Marvin was the first
California State Superintendent of Public Instruction. He came to
San Jose at the end of 1850 to assume the position, finding nothing of which he could take charge. There was a legislative vacuum, which he proceeded to fill through the state legislature in stop-gap fashion, having consulted
John C. Pelton who had recently set up a school in San Francisco. A clumsy and much amended school bill of 1851 was signed into law by Governor
John McDougall, as California's first schools legislation. At the 1853 state Democratic convention, Paul K. Hubbs was nominated for Superintendent of Public Instruction ahead of Marvin. A John G. Marvin Elementary School is now in
San Diego, founded in 1956. Concurrently with his activities on behalf of education, Marvin associated with
Jim Savage. At the end of the
Mariposa War, he became quartermaster of the
King's River Reservation, and business partner of Savage. Marvin was present at the quarrel between Savage and Walter Harvey in 1852, when Harvey shot Savage dead. ==Death==