[2] Born in North Adams, Massachusetts, he attended Drury High School where he was captain of the baseball team in 1920.

[2] After graduating, he went to Williams College, where he continued to play baseball and was captain during his final season in 1925.

[1] In 1932, O'Brien was a member of the United States men's field hockey team, which won the bronze medal.

[1] In 1934, he was appointed to the American Olympic committee, in recognition of the role he played as secretary and treasurer of the Field Hockey Association of America.

[3] In 1936, he was a member of the American field hockey team, which lost all three matches in the preliminary round and did not advance.