Born in Tennessee, John Foster McMahan was 14 years old when his family moved to Webster County, Missouri. McMahan volunteered for service during the Mexican American War, serving I Company G, 3d Missouri Mounted Infantry. After this war, McMahan headed west in search of riches in the California gold fields, returning to Missouri in 1851 where he engaged in farming and stock trading. In August 1862, McMahan raised a company and was commissioned captain of Company D, 74th Enrolled Missouri Militia. On December 20, 1862, McMahan was promoted to major of the regiment. On October 1, 1863, McMahan was promoted to lieutenant colonel in the 72d En-rolled Missouri Militia. On November 1, 1863, the 6th Provisional Enrolled Missouri Militia was organized with McMahan as the regiment’s lieutenant colonel. In November 1864, the regiment was redesignated the 16th Missouri Cavalry with McMahan as its commander. McMahan was promoted to colonel on March 22, 1865 and mustered out on July 1, 1865. After the war, McMahan was elected to the Missouri State Legislature.
Missouri Adjutant General. Annual Report of the Adjutant General of Missouri for 1864, 52–53.
Southern Historical Press, “Colonel John F. McMahan.” In History of Laclede, Camden, Dallas, Webster, Wright, Texas, Pulaski, Phelps and Dent Counties, Missouri, 865–66.
Fyan, “Colonel John F. McMahan.” Missouri Historical Review 29, no. 1 (October 1934): 56–57.
US Adjutant General, Official Army Register of the Volunteer Force of the United States Army for the Years 1861, ’62, ’63, ’64, ’65, Part VII, 895-898.