After General Lee's surrender at Appomattox Court House, Mann read law. He began practicing law in Nottoway County in 1867, and became involved in Democratic Party politics, eventually with what became known as the Martin Organization organized by future U.S. Senator
Thomas Staples Martin. In 1890, the Virginia General Assembly elected Mann judge of Nottoway County. However, his judicial career proved brief. Voters from Nottaway County, together with those from adjacent
Lunenburg and
Brunswick Counties elected Mann to represent them in the Virginia Senate in 1899, and re-elected him several times, although after the 1900 census and 1902 State Constitutional Convention redistricting, the state senatorial district (now numbered the 28th) was redrawn to include not only Nottoway and Lunenburg Counties, but
Amelia,
Prince Edward and
Cumberland Counties instead of Brunswick County (which was put into the 25th District along with
Mecklenburg County and represented by F.B. Roberts). (Mann's Senate predecessor,
Robert Turnbull, was also a lawyer and was elected clerk of Brunswick County in 1901 and later to the U.S. Congress). Senator Mann became chairman of the committee to revise Virginia Laws. In 1906 he introduced legislation to construct 450 high schools in Virginia, the most progressive educational funding to that date. Mann also favored
Prohibition, but only at the state level; the "Mann Law" he authored closed about 800 saloons in counties lacking police protection. 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. Upon taking office in January 1910, Mann became the last
Confederate soldier to serve as Governor of Virginia. Governor Mann continued to advocate temperance and public education. 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. ==Later years and death==