Born in Lowell, Massachusetts, on May 4, 1907, Mary Hallaren was educated at the state teachers college in Lowell. While teaching in Lexington, Massachusetts, she traveled extensively in Europe, the Near East, and South America. In July 1942 she entered the Officer Candidate School of the newly organized Women╒s Army Auxiliary Corps. In July 1943, with the rank of captain, she was named commander of the first battalion to go overseas (the WAAC was redesignated the Women╒s Army Corps in that month and became a component of the Army of the United States). She served as director of WAC personnel attached to the Eighth and Ninth Air Forces, and in March 1945, by which time she had advanced to lieutenant colonel, she was appointed director of all WAC personnel in the European theater.
In June 1946 Hallaren became deputy director of the WAC, and in May 1947 she succeeded Colonel Westray B. Boyce as director, taking the rank of colonel. With the enactment on June 12, 1948, of the Women╒s Armed Services Integration Act the WAC became a component of the Regular Army; in consequence, in December of that year, Colonel Hallaren became the first woman to receive a commission in the Regular Army (except for those in the Medical Corps, made part of the Regular Army in 1947). She continued as director until January 1953, when she was succeeded by Colonel Irene O. Galloway, and she retired from the army in 1960.
In 1965 Hallaren became director of the Women in Community Service division of the U.S. Labor Department. She retired from this position in 1978, but continued to consult to WICS and other organizations. In retirement she remained active in civic affairs, serving for many years on the board of directors of the WAC Foundation and lecturing on the history of women in the Army.
