World War II
World War II, second global conflict lasting from 1939 to 1945 that involved civilian populations on an unprecedented scale. Military deaths probably amounted to some 17 million, but civilian deaths were undoubtedly much higher because of mass bombing of cities, starvation, epidemics, massacres, and other war-related causes. The parties to the conflict involved nearly every major power in the world, divided into 2 groups: the Allies (principally Great Britain, the United States, the Soviet Union, and China) and the Axis Powers (principally Germany, Italy, and Japan). The development—and use—of the atomic bomb late in the war ushered in the nuclear age.
Causes of the war
The conflict arose because of the increasing military might of the aggressive, totalitarian regimes in Germany, Italy, and Japan following World War I. The harsh terms of the Treaty of Versailles after World War I had left Germany bitter and unstable, and hard economic times plagued much of the world in the 1920s and 1930s. These conditions fostered fascistic dictatorships in Germany and Italy, and Japan became aggressively militaristic and expansionist in Asia. Attempts to contain the aggressive impulses of these states through the League of Nations (which the U.S. did not join) proved ineffectual. With the rise of Hitler and Nazism to power in Germany (1933), the Versailles arrangements began to crumble. Germany rearmed and, on the pretext of defending German ethnic nationals in certain neighboring countries, laid claim to some of their territories. Hitler annexed Austria in Mar. 1938 (the Anschluss) and obtained the Sudetenland (in Czechoslovakia) through the Munich Pact (Sept. 1938). The policy of appeasement practiced at Munich failed, however, as Germany in Mar. 1939 occupied the rest of Czechoslovakia. On Aug. 23, 1939, Germany signed a non-aggression pact with its former arch enemy the Soviet Union, clearing the way for Hitler to move westward.
Outbreak of the war
Germany invaded Poland on Sept. 1, 1939. France and Britain responded by declaring war on Germany (Sept. 3). Germany, using the blitzkrieg strategy of speed and surprise, soon overran most of Poland, and on Sept. 17 Soviet forces invaded Poland from the east. By the end of September the Soviets had occupied the eastern third of Poland while Germany held all the rest. The Soviet Union continued with invasions of Finland and the Baltic states, as Germany went on to swift conquests of Denmark and Norway (Apr. 1940), and in May overran the Low Countries and invaded France. By June German troops had swept through France to the English Channel. British forces, almost trapped by the Germans, effected a desperate evacuation from Dunkirk back to England. France accepted an armistice on June 11, although Free French forces led by Gen. Charles de Gaulle continued the struggle. With Germany and Italy dominant on the continent, Hitler turned his sights on Britain, and attempted to bomb the nation into submission. Inspired by their leader, Winston Churchill, the British held firm and the Royal Air Force thwarted the effort in the Battle of Britain. In May 1941 Hitler broke off the massive air attack and began rebuilding his depleted air force. He continued, however, to harass British shipping with submarine warfare in the North Atlantic principally. On June 22 Germany invaded the Soviet Union, bringing that country, under its leader Joseph Stalin, into the war. Surprised, the Soviet forces initially suffered heavy losses. However, with Moscow and Leningrad surrounded and under siege, resistance stiffened. Also, a severe winter in 1941 caused enormous hardship for the German army, and they were never able to fully capture either city. Late in 1941 Germany and Italy found a new ally in Japan, whose aggressive militarism was bent on the conquest of Eastern Asia and the Western Pacific. On Dec. 7,1941, Japan surprised and crippled the U.S. fleet at Pearl Harbor, Hawaii. President Franklin Roosevelt asked for, and obtained, an immediate U.S. declaration of war.
Turn of the tide
Though the United States initially fared badly in the Pacific, its first major victories were recorded at Coral Sea and Midway (June 1942). In North Africa, Allied supremacy was established at the Battle of El Alamein (Oct.-Nov. 1942). On the eastern front the Germans lost an army at the siege of Stalingrad (early 1943), and Soviet forces began to push the invader back. Sicily fell to Anglo-American forces in July 1943, and the Italian dictator Benito Mussolini was driven from power.
D-Day (June 6, 1944) signaled the last phase of the war in Europe, as Allied troops stormed across the Channel and invaded Normandy. By Sept. 1944 German forces, already expelled from the Soviet Union, had been driven out of France and Belgium. The Battle of the Bulge (Dec. 1944) proved to be the final German counter-offensive. By Jan. 1945 the Allies resumed their drive into Germany; the Russians captured East Germany, and the Allies broke the Siegfried Line in March. As Russian forces at last entered Berlin, Hitler committed suicide (Apr. 30, 1945) and 8 days later all German resistance ended. The fate of conquered Europe was subsequently settled at the Yalta Conference and the Potsdam Conference, although Germany itself was not reunited into one country until 1990.
Defeat of Japan
Since 1943 Allied forces had been eroding Japanese power in the Pacific and Asia. By mid-1945 island-hopping assaults by U.S. forces, culminating in Iwo Jima and Okinawa, had largely swept Japan from the Western Pacific. The Soviet Union declared war on Japan and occupied Manchuria, and U.S. and Allied forces were massing in the Pacific for an invasion of the Japanese homeland. President Harry Truman ordered the dropping of the atomic bomb on Hiroshima and Nagasaki (Aug. 6 and 9), and on Aug. 14 Japan accepted unconditional terms of surrender.
Aftermath of the war
The stupendous destruction of World War II left much of the world in ruins, with the Soviet Union and the United States emerging as the 2 world superpowers. A struggle, known as the Cold War, soon developed between the Communist world, led by the Soviet Union, and the non-Communist world, led by the United States. Perhaps most important of all, the horror of nuclear devastation was introduced as a possibility in any future global conflict.