I checked a reference I have published by the Dept of the Army called " Unit Citation and Campaign Participation Credit Register " and this is what I found . The 559th FA Bn earned the following Battle Credits:
1. Ardennne-Alsace. 2. Central Europe 3. Normandy 4. Northern France 5. Rhineland.
No unit citations given.
Assuming this was his unit overseas ,from day 1 on landing in Europe with the unit, and not only at the time of discharge he would have had 5 battle Stars on his ETO ribbon (translates into 1 silver one )