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