All the actors who played the major Nazi characters on the show were Jewish and all had served in the US Army or assisted the US Army overseas in some way. That was info I learned from one of the retro TV sites that broadcasts the old show. Everyone involved with Hogan’s Heroes was very proud of that fact.
Major Hochstetter was played by Howard Caine (born: Howard Cohen) who fought with the US Navy in WW II fighting the Japanese in the Pacific Theater of War.