McIntyre was born in 1908 in Boston and was educated at the Boston Latin School 1919-1924, graduating from Newton High School in 1925. He attended Yale University, receiving his BA degree in 1929.
At Yale, Mac was president of his fraternity, made Phi Beta Kappa, and held a Harkness Scholarship, as well as becoming a Rhodes Scholar. He attended Oxford University from 1930-32, receiving both a BA and his Bachelor of civil law degrees. He returned to this country and attended the Yale Law School, graduating in 1933 with a J.S.D. degree.
Mac was a fine high school athlete, but did not have the opportunity to play lacrosse at that time. Upon entering Yale, Mac played freshman football in the fall and lacrosse in the spring. He won four letters at Yale, being the captain of the 1929 team, and was elected to the All-American first team in his senior year.
Upon reaching Oxford, Mac continued playing lacrosse, winning three letters there, and captained the 1932 team. The 1932 team was the champion of England, and Mac organized the combination of Oxford-Cambridge team that toured the United States in 1931, playing 15 games and losing only to St. John's. Among their victories were wins over both Army and Navy. Mac had the distinction of being picked three times on the All-Star English team.
Mac was an associate in the law firm of Sullivan and Cromwell from 1933 until 1942, when he entered the service as an Air Force lieutenant and reached the rank of colonel before he was demobilized in 1946. He was awarded the Legion of Merit and three Battle Stars. He became a partner of the law firm of Debevoise Plimpton Lyons & Gates and was with this firm until 1957, when he became Under-Secretary of the United States Air Force, serving for two years.
Mac was president of Eastern Airlines from 1959 until 1963 and started the famous "Air Shuttle" between Boston-New York-Washington. He was an executive at the Martin Marietta Corporation from 1964-1972, then he practiced law until his retirement in 1987. He was a director of several large corporations, and very active in all community affairs, having been elected mayor of Scarsdale in March 1967.
Mac McIntyre passed away in 1992.