Algernon Sidney Mountain Morgan was born on May 9, 1831 in Morganza, Pennsylvania. He graduated from Western University in Pittsburgh in 1849, and worked as a civil engineer and coke manufacturer.
On April 25, 1861 he became Second Lieutenant of Company K in the 12th Pennsylvania Volunteer Infantry, a ninety day regiment which mustered out on July 31. The next day, August 1, 1861 Morgan became lieutenant colonel of the 63rd Pennsylvania Volunteer Infantry.
In March of 1862 the regiment was moved to the Peninsula as part of Heintzleman’s Third Corps. At the Battle of Fair Oaks on May 31, 1862, Morgan was shot in both hips. While still invalided due to his injury – he was forced to lie face down for 13 months after his wound – he was promoted to colonel on September 29, 1862. Morgan never returned to field command, and was discharged for disability on April 18, 1863.
On December 5, 1863 he was appointed Military Storekeeper in the Ordnance Department at the Allegheny Arsenal with the rank of captain in the Regular Army. At one point in 1875 he was to have been transferred to the Rock Island Arsenal, and fearing his delicate health would not survive the change, submitted his resignation. On the intervention of Senator Simon Cameron, he was allowed to stay on at the Allegheny Arsenal, and retired from the Army on June 6, 1894. He then became a bank president.
Algernon S.M. Morgan died on March 10, 1914. He is buried in Allegheny Cemetery in Pittsburgh.