World War II in Europe Before dawn on September 1, 1939, German forces crossed into Poland in an attack so fast and brutal, they called it blitzkrieg, meaning lightning war. This time Britain and France decided to fight, and on September 3 they declared war on Germany. Roosevelt declared the United States’ neutrality, but within weeks asked Congress to lift the Neutrality Acts’ arms embargo that prevented Britain and France form buying American weapons. After weeks of debate, it agreed to sell arms to the Allies if they paid cash and carried goods in their own ships.After a lull in fighting over the winter of 1939 and 1940, Hitler launched an invasion of Norway and Denmark for resources such as the fjords.
Next the German armies swept into the Netherlands and Belgium, where for thefirst time they met resistance from the British and French troops. In the spring of 1940, German forces defeated the Allied army and drove it to the sea at the French town of Dunkirk, breaking through the Maginot Line. Cut off from retreat by land, the army was saved when 300,000 British and French troops were evacuated across the English Channel in a heroic nine day rescue effort aided by 600 private boats, known as Operation Sea Lion. In June 1940, Italy suddenly invaded France and declared war on Great Britain.
France surrendered and Britain faced Hitler alone. As the German air force bombed British airfields, factories, and cities to prepare the way for German armies to cross the English Channel, Britain found leadership in its new Prime Minister, Winston Churchill. For months, London suffered bombing day and night by hundreds of German planes. The fighter pilots of the Royal Air Force, however, kept the German from gaining control of the skies over Britain and forced Hitler to abandon his invasion plan. When Hitler attacked Yugoslavia and Greece in the spring of 1941, the Nazis overran those countries before lend-lease aid could reach t.