Harry Matthias devoted 30 years to the Archer Epler Musketeers, from 1955 to 1985, serving in a number of positions. He joined the corps as a bass baritone player, and later served as treasurer, corps director, as a member of the committee which founded the alumni corps, co-director, business manager, and on the board of trustees. He helped organize the first meeting of Drum Corps Associates in 1963 and was instrumental in organizing the Archer Epler Musketeers Alumni Association before the first alumni corps was formed. His drum corps activity began in 1948, with Hattel-Taylor of Philadelphia. He was a member of the Imhof Thunderbirds of Philadelphia from 1950 to 1954.