Lloyd F “Mickey” McGuire was born in Waukegan, Illinois. As a third baseman he signed with the Chicago Cubs organization and played for the Hopkinsville Hoppers of the Class D Kitty League in 1937, where he batted .242 in 122 games. In 1938, he raised his average to .285 with the Hoppers, and his .334 batting average in 1939 was among the best in the Kitty League. In 1940, McGuire was with the Madison Blues of the Class B Three-I League where his manager was Merv “Bud” Connolly, a former Red Sox infielder. He batted .237 in 121 games that season and entered military service at the end of the year.

McGuire served as a medical aid man through the North African and Sicilian campaigns and the Italian invasion. He carried litters and treated wounded soldiers under heavy shellfire for which he was awarded the Silver Star.

McGuire rose from the rank of sergeant to second lieutenant in December 1943, the first medical soldier to be commissioned in the Medical Administration Corps. “A lot of soldiers,” remarked McGuire to the Stars and Stripes at the time, “have the impression that the first aid man is a goldbrick who hasn’t the nerve to carry a gun. In my own experience, I’ve found first aid men in the field as courageous and devoted to duty as any hero in the thick of the fight.” 

Fifty per cent of all medics McGuire served with were casualties themselves and his own squad spent 103 days in the frontlines treating and evacuating the wounded.

McGuire returned home in late 1945. In January 1946, he attended the Cubs’ advanced spring training group for former servicemen at Lake Worth, Florida. He was assigned to the Portsmouth Cubs of the Piedmont League for the season where he batted .213 with 8 home runs and 80 RBIs in his last year in organized baseball.