Hugh Mulcahy was born September 9, 1913, in Brighton, MA.

In high school, Hugh was named to Boston's All-City team, and, in 1932, pitched with the Allston Braves of the semipro Boston Twilight League. Hugh's performance earned him a tryout with the New York Giants in 1933 and an assignment to North Attleboro of the New England League. For 1934, Hugh signed with Manchester in the Northeastern League and compiled a 14-10 record.
Hugh was invited to the 1935 spring training with the Washington Senators, but left for Albany of the International League, where owner Joe Cambria was convinced of Hugh's potential and tried to trade him to the Phillies, who were struggling in pitching.

Hugh was brought in for a tryout and, at age 21, made his Major League debut as a relief pitcher for the Phillies in Pittsburgh's Forbes Field, retiring in succession future MLB Hall of Famers Paul Waner, Lloyd Waner, and Arky Vaughan. In 1937, Hugh was the stronghold of the Phillies' staff, leading the league with 56 appearances and 261 innings as a starter and in relief. In 1938, Hugh made 46 appearances, with 34 starts, pitching 267.1 innings, with a 10-20 record. In 1940, Hugh was named to the National League All-Star team, started 36 games, and completed 21, the third most in the league.

On March 8, 1941, one day before he was to report to spring training, Hugh was drafted into the military, becoming the first Major League player to be drafted for World War II. Instead of throwing fast balls, Hugh spent 53 months in the U.S. Army serving in the Pacific Theater during World War II. Hugh was awarded a Bronze Star for his meritorious service. Upon his discharge on August 5, 1945, Hugh immediately rejoined the Phillies and pitched in five games, receiving a standing ovation from the Philadelphia fans as he took the field for the first time upon his return home from the war.

In 1946, Hugh asked the Phillies to be released, but he was not released until January 28, 1947. Hugh then signed as a free agent with the Pittsburgh Pirates, to be close to his wife in their home in Beaver, PA. In 1947, Hugh finished his Major League Baseball career with the Pirates. Hugh finished his baseball career in 1951 after going 9-15 with the Albany Senators of the Eastern League, completing a circle that began over 16 years earlier on his way to the majors, when he wore an Albany uniform.

The White Sox, impressed by his temperament and experience, hired Hugh as a minor-league pitching coach and scout. He stayed with the White Sox for the rest of his career, retiring more than 20 years later. Hugh ran minor-league training camp for the White Sox for years and in 1955 invented a machine that returned the ball automatically to the pitcher. In 1974, Hugh was named White Sox Man of the Year for his work in improving young pitchers in the club's farm system.

Hugh Noyes Mulcahy died October 19, 2001, at age 87, in Aliquippa, PA.