Which Major League Baseball player is the only person to have served in both World War I and II?

The Major League Baseball (MLB) player who was the only person to have served in both World War I and II is Hank Gowdy. He was a member of the 1914 "Miracle" Boston Braves and became one of the first active major league players to enlist and service in World War I.

During WW I while in the Lorraine region of France, Gowdy endured trench warfare. He faced brutal situations as the Germans made a last fierce effort to overrun the Allies on the Western Front. Gowdy carried the colors for the Fighting 42nd and returned to the United States a genuine hero.

At the age of 53, he served in World War II as a captain and was later promoted to major in the U.S. Army. In December 1944, he went to work at Fort Benning, a U.S. Army base on the Alabama-Georgia border next to Columbus, Georgia. He served as Chief Athletic Officer on the base.