The period you refer to was the Occupation. No way to tell whether he actually served during the war. You've discovered the scarcity of local information. The only "government" was the American Constabulary (and their duties didn't include recording vital statistics). I've sent you a list of telephone numbers (if you score a "hit" he/they can give you an address). A couple are possible relatives/next of kin, the rest may be he himself (try #3 on the list first). Send (e-mail) me a progress report.