Hard to tell. It appears to be a commemorative or memorial medal for some unit or units which fought at Arnhem, Stalingrad, and Normandy, plus one other (lower right) which I can't read in your photo. The emblem in the center (standing lion) looks like some of the Belgian insignia still used today, and could be a German symbol as well. The concept of a single unit or organization which fought at Arnhem, Stalingrad, and Normandy would imply that we are talking about a German unit. Essentially only the Germans and Russians were at Stalingrad (plus a small polish unit supporting the Germans), and Arnhem had the Brits and Americans mostly on the offensive (none of which were at Stalingrad) against the Germans. Normandy sides are well-known. So, bottom line is that I don't know for sure, but I can pretty definitely declare that this is not any kind of a formal military insignia, but some kind of a commemorative one. I would bet German, but this is far outside my collecting expertise.