He was born in Sweetwater, Texas, played high school football there, and was one of the top high school players in the state.
He led the NCAA major colleges in 1942 with 403 receiving yards.
[3] Flanagan sustained a knee injury in 1943 that prematurely ended his season, nonetheless he was named 2nd Team All-Southwest Conference.
[4][5] After the 1943 season, Flanagan spent two-and-a-half years serving in the United States Navy during World War II.
He opted not to return to football in 1947, stating that he was retiring from the game due to the lingering impact of the knee injury he sustained in 1943.