I have a quick question - why was Silesia divided in two after the first world war? I can't find any reason for it online.
Short and dirty version: First idea was to give the whole region to Poland, but GB vetoed that. Instead, "pure" Polish or German regions excluded, the plebescite was held, which Germany won 60 to 40. The British-Italian solution, who offered only minor concessions (about 25% of Silesia) in line with the results to Poland, did not go down well with Polish nationalists. Thus they started with support from the Polish Army the third Silesian uprising, hindered by Italian, but not French occupation troops on their way. The compromise afterwards gave the important industrial parts, including some predominantly German areas, to Poland, leaving the larger, but mostly agrarian region for Germany. In Germany that was seen as a unilateral renegotiation of the already hated Versailles treaty by the victors and an occupation of German core territory by Poland, making a border revision a crucial goal for every German party including the communists, at least as important as a revision of Versailles.