The year 1939 turned out to be a fateful one for Europe and the world. On September 1 of that year, Nazi Germany's invasion of Poland began a conflict so vast that it quickly received the designation of World War II, requiring that the earlier so-called Great War become World War I. Germany felt confident about its move east, because on August 23, 1939, Hitler and Stalin had agreed to a non-aggression treaty, eliminating for a time the possibility of a two-front war in the east against the USSR and in the west against France and Great Britain (who had come to Poland's defense). The treaty contained secret protocols laying out German and Soviet spheres of influence in eastern Europe, in which the eastern Baltic littoral figured prominently. Germany ultimately declared itself to have no interest in the littoral, in effect giving the USSR a free hand in the region. The Soviet Union responded quickly, invading Poland on September 17 and in fact occupying a slightly larger but less populous section of the country than Germany brought under its control. It might be added that earlier, in March, Poland itself had benefited from Hitler's earlier dismemberment of Czechoslovakia by demanding and receiving that country's Teschen region, with some 240,000 inhabitants. In any event, Great Britain and France declared war on Germany on September 3.