I think there's a barrier there that isn't what it seems. They still live under the "jews do no wrong" "jews are best friend" mindset. Ignoring the fact, like stated in the title, that it was jewish poles and jewish russians who were killing the Germans in what was German territory of Danzig. So until you're able to break through the "jews oppressed" lie and able to tell a truthful recount of history they won't be able to see it for what happened. Because to them Germany did invade and attack poles and russians on polish territory thanks to the (((treaty of versailles))). Get past that and the rest is easy. Keep in mind I don't live in Europe so I don't know firsthand at all if what I wrote is correct, but it doesn't seem like it would be too off.