A snapshot of history that may be of interest as to why your grandfather considered himself German heritage. Up to 1918 and the end of WW1 the long established Austrian-Hungary Empire was ruled by the Hapsburgs. In those centuries there were numerous German enclaves and geographic areas all the way to the Volga River and the Black Sea. Large numbers were in the Crimea (Black Sea Germans - Schwartzmeer Deutsche) and Central Russia (Volga Deutsche). These enclaves were hard hit in the Stalin years and most were forced to Siberia. Along the Hungarian/Serbian border were the Donauschwaben - Danube Schwaben. May of these generations are still there today. There are still such enclaves in Hungary and Romania. The area of Kösice (or Kaschau in German) was one of these enclaves. In 1900 it was the capitol of the Hungarian provence of Abauj-Torna, with a population of about 29,000 and was the seat of a Bishop with a cathedral. It remained part of Hungary until 1945. Hope this helps in providing some insight into German heritage in these areas of eastern Europe.