2nd Lieutenant Samuel B. Ashby enlisted in Captain Henry Mulrennan’s Florida Volunteers Coast Guards on November 27, 1861 as a coxswain. He was promoted to 3rd Lieutenant on January 31, 1862, and later brevetted to 2nd Lieutenant. He served with this organization until April 25th, 1862.
He was enlisted in Captain Smith’s Company (Key West Avengers), 7th Florida Infantry Regiment on April 25th, 1862 by Major R. B. Thomas at Tampa, Hillsborough County, Florida for 3 years or the war. His name appears on a Register containing Rosters of Commissioned Officers, Provisional Army Confederate States as being elected 2nd Lieutenant on April 25, 1862. He is reported as present on all company rolls from that point until the period April 30 through November 14, 1862, where he is reported absent sick at Knoxville, Tennessee since November 1.
He submitted his resignation to Secretary of War James A. Seddon on December 1st, 1862. This letter was forwarded with favorable endorsement by Brigadier General W. G. M. Davis on December 26, 1862, stating in part that “…I am informed by the Lt. Col. commanding the 7th Regt. that he ( Lt. Ashby) has tendered his services to act as Pilot to a Gunboat built by the C.S. Navy now ready for sea on the Chattahoochee River and that the Navy Department wish to employ him at once.”
His name appears on a Register containing Rosters of Commissioned Officers, Provisional Army Confederate States as resigning on January 15, 1863.
He last appears on a roster of the ''CSS Chattahoochee" dated 1863, as “S. B. Ashby, assistant boatswain”.