[1] Messmore next went on to serve in the 31st Wisconsin Volunteer Infantry Regiment during the American Civil War, attaining the rank of colonel.

After the end of the war, Messmore resettled in Washington, D.C., where he was very soon appointed assistant commissioner of the Internal Revenue Bureau.

While in Washington, in 1867, he acquired the Meridian Hill estate, an older property which sat a short distance north of the White House; he then subdivided this tract of land, and its lots were sold to create a new neighborhood.

Messmore subsequently moved to Grand Rapids, Michigan, where he purchased and became, in 1881, the editor and publisher of the newspaper The Democrat.

He relocated to California, in 1886, first to Orange County, and then to Los Angeles, where he formed a successful law partnership with fellow Wisconsin transplant Amasa Cobb.