However, Jachym's baseball and journalism careers were interrupted by World War II. In 1941, Jachym enlisted in the United States Marine Corps and rose to the field rank of captain. He saw combat at New Guinea, New Britain and Guadalcanal, earning a Silver Star. At war's end he relocated to Jamestown, New York, became a successful businessman, and—still in his 20s—purchased the local minor league baseball franchise, the Jamestown Falcons of the Class D PONY League. When he in turn sold the Falcons to the Major League Detroit Tigers, he joined the Tiger front office as assistant director of minor league operations.