His undergraduate studies were interrupted for two years by service in the United States Navy as a communications officer on Okinawa during the Second World War.
Following degrees at Harvard University (BA, 1946) and the General Theological Seminary in New York (STB, 1949), he was ordained to the priesthood in April 1950 by Bishop Oliver Leland Loring of the Episcopal Diocese of Maine.
Garfield is notable primarily for his advocacy of the principles of the Liturgical Movement in the Episcopal Church, and for his work on the committee that revised the 1928 Book of Common Prayer (BCP).
His most significant national role was as rector of the Church of St. Mary the Virgin, Times Square, from 1965 to 1978, when the parish's liturgical usage was an acknowledged important standard for international Anglo-Catholicism.
Garfield notably changed parish practice away from the model of a "non-communicating High Mass" at which only the celebrant had received Holy Communion during the principal service from approximately 1868 to 1965.