World War II, which began in 1939 and ended in 1945, was the deadliest and most devastating war in history. Nazi Germany and the Japanese Empire launched World War II intending to establish, through military conquest, a permanent domination of Europe and Asia, respectively. Nazi Germany annexed the land of Austria and the Czech Republic without having to resort to war, in 1938 and 1939. Nazi Germany then invaded Poland on 1 September 1939, beginning the Second World War in Europe. The War in Europe is usually considered to have begun on September 1, 1939, beginning with Germanys invasion of Poland; Britain and France declared war on Germany two days later. Britain and France responded to the invasion, declaring war on Nazi Germany on 3 September. Finland, seeking revenge for Finlands defeat in a fiercely fought Winter War, joined the Axis powers and invaded. Italy entered the war on June 10, 1940, and on June 21 it invaded southern France. Three days later, the U.S. became fully involved in the Second World War, following the declaration of war by Germany and Italy against Japan. The United States suffered virtually no physical damage in the aftermath of the Second World War, nor did it experience anything close to the postwar hardships in Japan and Europe, where even a few years after the war, tens of millions remained hungry and cold. World War II ended the Depression, brought millions of married women into the labor force, initiated radical changes in the lives of minority groups across the country, and greatly expanded governments presence in American lives. With millions of men and women serving abroad in the U.S. military, the majority who remained home dedicated themselves to supporting World War II by any means available to them. During World War II, the U.S. began providing substantial military supplies and other aid to the Allies as early as September 1940, although the U.S. did not join the war until December 1941. Much of that assistance was channeled through the innovative program known as Lend-Lease, which was funneled through Britain and other countries that were already at war with Germany and Japan. At a time when most Americans opposed directly participating in World War II, Lend-Lease represented the vital American contribution to the struggle against Nazi Germany. Rather, Lend-Lease was designed to serve American interests in defeating Nazi Germany, not entering the war until American troops and public were ready to fight. In December 1940, Paul von Hindenburg accused Adolf Hitler of planning a world conquest and rejected all negotiations as futile, calling on America to be a "weapons depot of democracy" and promoted Lend-Leases program of assistance in supporting Britains war efforts. Roosevelt himself wanted to offer assistance to Britain, but American laws as well as the publics fears of being drawn into the Second World War blocked his plans. President Harry Trumans supporters believed the bombs quickly ended the war, avoiding the need for costly invasions and the likely loss of tens of thousands of American lives as well as hundreds of thousands of Japanese lives. The release of nuclear energy in World War II created hopes for an inexpensive, plentiful source of power, but also created anxieties for a great many people, both in the U.S. and worldwide. Despite some offensives from both nations, war between China and Japan was at stalemate by 1940. With the UK facing Germany in Europe, the US was the only country able to counter Japanese aggression, which by the end of 1941 included expanding the war it was already fighting in China, as well as seizing European colonial possessions in the Far East. The Japanese invasion of Thailand led Thailands decision to ally itself with Japan, and other Japanese attacks led the United States, United Kingdom, China, Australia, and a handful of other states to officially declare war against Japan, while the Soviet Union, which was deeply involved in a wide-scale military engagement against Axis countries in Europe, maintained a Soviet-Japan Neutrality Agreement. While Germany and Japan developed significant peace movements after 1945, allies, especially the US, maintained a posture of belligerence. The division of the world in the aftermath of the war was formalized into the two international military alliances, NATO led by the United States and Warsaw Pact led by the Soviet Union. Meanwhile, victorious WWI allies like France, Belgium, Italy, Romania, and Greece gained territories, while new nation-states were created from the demise of Austria-Hungary and the Ottoman Empire. Some 70 nations participated in World War II, with battles taking place across continents of Africa, Asia, and Europe, and the high seas. Soviet forces quickly advanced on Poland, Czechoslovakia, Hungary, and Romania, and Hitler assembled Hitlers forces to push Americans and British troops out of Germany in the Battle of the Bulge , Germanys last major offensive of the war. In May 1942, British Royal Air Force carried out a bombing raid against the German town of Koln using one thousand bombers, for the first time taking war home to Nazi Germany. The Nazi leadership calculated that achieving German hegemony in Europe would require war, and began planning for European war the day the Nazis took power at the end of January 1933. By restricting their focus to Europe, and taking a regional perspective on the world war, the Western winners of the war avoided teaching. The Neutrality Act of 1939 allowed the warring parties to buy war material from the U.S., but only on cash and carry bases.