[3] Initially, the 12th Virginia guarded the vital Norfolk naval yard and port, and the city of Petersburg (an important rail hub and transshipment point).

Mann was severely injured during its first significant combat, the Battle of Seven Pines, on June 1, 1862, and during his recovery, he briefly served as a clerk in the Confederate Treasury department in Richmond.

[4] Upon partially recovering from his wounds, Mann resumed his office as Deputy Clerk in Nottoway County as the war ended.

[6] Mann was elected Virginia's governor in 1909 with 63.35% of the vote, defeating Republican William P. Kent and Socialist Labor candidate A.H. Dennitt.

[6] During his governorship, Mann refused to prevent the execution of the teen-aged Virginia Christian, a black house maid who was convicted of murdering her white employer, and the subject of a nationwide campaign for clemency.

[7] In 1911, Mann shook hands with President William Howard Taft as part of the Manassas Peace Jubilee marking the 50th anniversary of the First Battle of Bull Run.

Upon leaving office in 1914, Mann returned to his legal practice in Nottoway County and continued to remain active in the Democratic Party.