The Colonels were one of few minor league teams to play throughout World War II, and they won pennants in 1944 and 1945.

They won (in 1960, with pitcher Phil Niekro) one of three appearances in the Junior World Series in that time, but in 1962 the American Association folded.

In October 1967, Walter J. Dilbeck purchased the Toronto Maple Leafs of the International League and moved them to Louisville, renaming them the Colonels.

During this stretch, players included Carlton Fisk, Dwight Evans, Luis Tiant, and Cecil Cooper.

The franchise had to move when the Kentucky State Fair Board announced that Fairgrounds Stadium would be renovated for football in a manner that would make it unsuitable for baseball.