The Polish September Campaign also known as The Polish-German War of 1939. Started September 1,1936 ended October 6, 1936. Germany attacked quicklu without any warning using the military term Blitzkrieg also known as lighting war. They invaded Poland from the north, south, and west. This event marked the start of World War II as Poland's western allies, the United Kingdom and France, on September 3 declared war on Germany.