Jespen served in the US Army during WW II as a combat infantryman with the 30th Infantry Division in Europe. General Eisenhower's historians rated this division as the #1 division with the most consistent and efficient battle service in Europe during WW II. He landed on Omaha Beach July 4, 1944 and served as Instrument Corporal and Machine gunner in CO D> 120th Infantry Regiment in the five major battle campaigns from Normandy to the Elbe River.