Dunn was born in
Grove City, Pennsylvania. In February 1937, Dunn was named head football and basketball coach at Northeastern. He remained with the school until March 1942, when he entered the
United States Army. In February 1946, he elected to remain in the Army and resigned his position at Northeastern. However, five months later, he returned to coaching as an assistant at
Lafayette. In 1947, Dunn became the varsity backfield coach at
Brown. From 1949 to 1951, he was the defensive backfield coach at
Yale. In 1952, Dunn moved to the
Interprovincial Rugby Football Union as an assistant to
Peahead Walker with the
Montreal Alouettes. Walker and Dunn had previously coached together at Yale. In 1961, he became an assistant under
Steve Owen with the
Saskatchewan Roughriders. In 1963, he and Owen joined the Syracuse Stormers of the
United Football League. In 1964, he returned to Canada as the backfield coach of the
Toronto Argonauts. He returned to Montreal the following year as an assistant under
Jim Trimble. Dunn then served as a football coach and teacher at
Sanford High School in
Sanford, Maine. He was relieved of his coaching duties prior to the 1970–71 school year. ==Personal life==