Americans strongly favored isolationism in the early 1930s. With the bitter memory of the first world war and the challenge of economic problems at home, America did not want the nation to become entangled in another war. FDR took no direct action against aggressive dictators in Asia and Europe. FDR also spoke out against aggression in principle and he vowed that the U.S. would be a "good neighbor" and "respect the rights of others."
Hitler announced his plans to absorb Austria and Czechoslovakia into the Third Reich to his advisers. Treaty of Versailles prohibited Anschluss. In March 1938, Hitler sent his army into Austria and annexed it.
After the nonaggression pact with the Soviets repealed, Hitler moved ahead with plans to conquer Poland. His surprise attack took place on September 1, 1939 when German tanks and troop trucks rumbled across the Polish border. German aircraft and artillery were used for a bombing at Warsaw, Poland's capital.
On September 17, Soviet troops occupied the eastern half of Poland. Stalin then moved to annex countries to the north of Poland. Lithuania, Latvia, and Estonia feel without a struggle but Finland resisted. 1 million troops were sent into Finland where they expected a quick victory and were not prepared for winter fighting.
After the fall of France, Great Britain stood alone against the Nazis. Winston Churchill declared his nation would never give in. In the summer of 1940, Germany's air force began bombing Great Britain. At first Germany focused on British airfields and aircraft factories but on September 7, 1940 they began focusing on cities. The Battle of Britain continued until May 10, 1941 when Hitler decided to call off his attacks after British resisted for so long.
With the Balkans in control, Hitler could move ahead with Operation Barbarossa, his plan to invade the Soviet Union. On the morning of June 22, 1942, German tanks and aircraft announced the beginning of the invasion. The invasion went on for weeks unto the Germans had pushed 500 miles inside the Soviet Union. Soviet troops retreated and burned and destroyed everything in the enemy's path.