This is an interesting topic, CJH, because I think that this was one of the unsung causes of WW2. The hundreds of thousands of Germans were forcibly evicted from the East so that the state of Poland could come into existence surely added a lot of fuel to Hitler?s arguments that Germany was being persecuted and needed a strong leader to take the reins. The scale of the deportations from some of these areas was staggering. I don?t have the stats handy, back offhand it seems to me that 90% of Germans living in Slask (Silesia) were forcibly deported. Remember that there was no resettlement assistance or compensation: these were forced deportations that caused considerable suffering. Also remember that these disenfranchised people would be ready recipients of Hitler?s xenophobic rhetoric. Germany was, in its collective mind, losing the battle of "Social Darwinism".
However, today, the chances of a German/Polish war over land is scant. Germany officially agreed to the new borders after the war and has no claims that I am aware of. (though some German maps still use German rather than Polish names, I note, for certain cities ---- Danzig/Gdansk for example)
As for the Eastern border, it?s a mess. Much of Russia?s heritage is in Ukraine as is much of Poland?s. Lwow is considered by many to be a center of Polish culture. Kiev was once a center of Russian culture.
All things considered, I think the main demands come from the Russians (Black Sea access, Crimea) and I don?t think the Poles have any serious territorial demands in the Ukraine. (Though I could be mistaken).
As a catalyst for war, I think it is quite possible. A major displacement of people, a civil war, a referendum on national identity, any of these factors could lead to war quickly drawing in the neighboring countries who all have territorial interests and agendas.
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