Whose defeat ended the anti-Polish campaign that began with the idea to unify all the German and possibly also Germanic-speaking peoples in a single nation-state known as "Großdeutschland".?
Expulsion of Poles by Germany: The Expulsion of Poles by Germany was a prolonged anti-Polish campaign of ethnic cleansing by violent and terror-inspiring means lasting nearly half a century. Pan-Germanism:  Pan-Germanists originally sought to unify all the German and possibly also Germanic-speaking peoples in a single nation-state known as "Großdeutschland".
i don't know