After head coaching stints at the San Diego Naval Academy,
Pasadena City College, and the
University of Denver, Blackman was named head coach at
Dartmouth College in 1955, where he was universally known among players and students alike as "The Bullet." In 16 seasons under Blackman, Dartmouth had a record of 104–37–3, including undefeated seasons in 1962, 1965, and 1970 while leading Dartmouth to their first conference title in 60 years in 1958. They would win it six more times in his tenure, including his final season in 1970. In his final season at Dartmouth, Blackman received the
Walter Camp Coach of the Year Award. In 1971, Blackman became the head coach at the
University of Illinois at Urbana-Champaign. In six seasons with the
Fighting Illini, Blackman had a record of 29–36–1. Blackman returned to the
Ivy League in 1977, where he replaced
George Seifert as head coach of the
Cornell University Big Red until 1982. ==Later years and death==