In 1939, Poland was invaded by Germany. The Germans said that the Polish troops provoked them along the German-Polish border.The Germans also used issues such as the dispute between Germany and Poland over German rights to the Free city of Danzig and the demand for a passage between East Prussia and the rest of Germany through the Polish corridor as excuses for the invasion.
This is a comparison between Poland in WW2 and Poland now. It was much bigger then than now.