What justified Germany attacking Poland? France and the UK both made it quite clear that if Germany attacked Poland they would be forced to declare war on Germany.
You claim to know about ww2 but no idea whats the Danzig Corridor? etc, etc?

THE TERM IS 'TERRITORIAL CLAIMS'
pre ww1

after ww1

Europe 1950

long after ww2, all of eastern Europe was part of the soviet uninion, now independent states.

Its not that I don't like English, I just don't like any place (or individuals) that points at Germany and says 'the bad guys' - they had rights too.