In the Munich agreement of 1938, Britain and France had caved in to Hitler’s aggression. In 1939, the Soviet Union proposed an international agreement to oppose further German demands for territory. Britain and France, who distrusted Stalin and saw Germany as a bulwark against the spread of communist influence in Europe, refused. Stalin then astonished the world by signing a nonaggression pact with Hitler, his former sworn enemy. On September 1, immediately after the signing of the Nazi-Soviet pact, Germany invaded Poland. This time, Britain and France, who had pledged to protect Poland against aggression, declared war. But Germany appeared unstoppable. Within a year, the Nazi blitzkrieg (lightning war) had overrun Poland and much of Scandinavia, Belgium, and the Netherlands. On June 14, 1940, German troops occupied Paris. Hitler now dominated nearly all of Europe, as well as North Africa. In September 1940, Germany, Italy, and Japan created a military alliance known as the Axis.
A newsreel theater in New York’s Times Square announces Hitler’s blitzkrieg in Europe in the spring of 1940.
For one critical year, Britain stood virtually alone in fighting Germany. Winston Churchill, who became prime minister in 1940, vowed to resist a threatened Nazi invasion. In the Battle of Britain of 1940-1941, the German air force launched devastating attacks on London and other cities. The Royal Air Force eventually turned back the air assault. But Churchill pointedly called on the “new world, with all its power and might,” to step forward to rescue the old.