[1][2] Mann was born in Mobile, Alabama but only lived there six months, since his father worked for the L&N railroad and soon moved his family to Texas and then Florida.

The United States Supreme Court ultimately decided the case in favor of Mann and his fellow northern Virginians in 1964.

Other education-related bills Mann sponsored created Virginia's State Educational Assistance Authority, and made millions of dollars available to construct public schools throughout the commonwealth.

He also sponsored bills to provide for statewide driver education and medical assistance to the elderly, as well as to ban obscene literature and billboards on Virginia's highways.

In the March 1969 special election after the death of his mentor, State Senator Charles R. Fenwick, Mann ran for that seat, but unexpectedly lost to Republican M. Patton Echols, whom he had defeated during his 1963 delegate reelection campaign.

Republicans led by George Mason Green Jr. swept Mann's successor Vivian Kallen and the other three Arlington Democratic delegates to the Virginia house aside.

[4] Mann also was the first President of the Arlington Historical Society and chairman of the Virginia Chapter of Americans for Effective Law Enforcement.