Mann studied at Southern Methodist University, where he was twice named to all-conference football teams and was nicknamed the "Little Red Arrow." He subsequently worked his way through Harvard Law School; first with a job at a garment factory, later as a minister at a Congregationalist church.
After returning to Texas, Mann worked as an assistant attorney general under James V. Allred. Mann was a progressive and a strong supporter of Franklin D. Roosevelt. He was elected attorney general of Texas in 1938 and held that post until he resigned in December 1943.[1] Mann aggressively pursued an agenda of trust-busting.
After resigning as Attorney General, Mann resumed private law practice in Dallas. Remaining active in Democratic politics, he was Texas director of the Kennedy-Johnson campaign in 1960.[2]
