The service cap resembles a Polish officer peaked hat. The brim looks patent leather with a silver edge. Difficult to be certain from the photo. Insignia on cap resembles Polish cat. As an officer he may be wearing shoulder boards, can't be certain.
Much of the Polish officer corp was killed by the Russians in 1940 at the Katyn Forest.

If the link doesn't work Google: WW2 polish officers peaked hat.

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