In the 1930s, the United States found itself largely preoccupied with the domestic economic troubles of the Great Depression, even as international crises loomed in Europe and Asia. Benito Mussolini, the fascist dictator of Italy, had begun waging an imperial war in Ethiopia using chemical weapons like mustard gas, slaughtering thousands of innocent people. A violent civil war raged in Spain, pitting General Francisco Franco's fascists against a motley alliance of communists and democrats. Josef Stalin had risen to absolute power in Russia after imprisoning and executing many of his political enemies in the Soviet Union. Downtrodden Germans had rallied around Adolf Hitler, their new leader, who called for Aryan redemption after Germany's humiliation in World War I and launched an aggressive campaign to "unify" the German race throughout Europe. And in the East, Japan had invaded Manchuria and threatened to conquer China, virtually unchecked by Western powers preoccupied with problems closer to home.
Through the troubled years of the late 1930s, Americans did everything they possibly could to avoid being drawn into these growing conflicts abroad. In the end, staying out of World War II proved impossible; by the middle of 1941, President Roosevelt had committed American ships to an undeclared (and possibly illegal) naval war with Germany in the North Atlantic, and on 7 December 1941 any question of America's further neutrality in the conflict ended with the devastating surprise attack by the Japanese against the American naval station at Pearl Harbor, Hawaii.
Once committed to the war, Americans committed themselves to achieving total victory on two fronts—victory over fascist Italy and Nazi Germany in Europe and victory over imperial Japan in the Pacific. Having pursued a policy of isolationism rather than rearmament during most of the 1930s, the United States found itself, at first, woefully unready to engage in combat with the fearsome military juggernauts of Germany and Japan. It took the Americans an agonizingly long time to begin to push back against their fascist enemies. The turning point in the Pacific didn't come until June 1943, when American airplanes crippled the Japanese navy at the Battle of Midway. In Europe, it took even longer for the Americans to open up a proper second front against Nazi Germany; by the time American troops stormed the beaches of Normandy, France, on D-Day (6 June 1944), the Soviet Red Army had already been engaged in a desperate battle of attrition against the Germans on the Eastern Front for three years. To an extent that most Americans today do not recognize, the Soviet Union did the lion's share of the work—and took the lion's share of the casualties—in defeating Adolf Hitler.
Victory did eventually come—in Europe in May 1945, in Asia three months later—but it came at a tremendous cost. Worldwide, an estimated 70 million people lost their lives, the majority of them innocent civilians—including 6 million European Jews ruthlessly murdered by the Nazis in modern history's worst genocide. Aerial bombing—targeted against both military-industrial targets and civilian morale—reduced great cities to rubble, from London to Berlin to Tokyo. Atrocious acts of barbarism—war crimes, even—were committed by soldiers on all sides. Nightmarish new instruments of death—gas chambers, unmanned rockets, atomic bombs—were invented and deployed for use against human beings.
World War II was, quite simply, the most deadly and destructive conflict in human history.
Why, then, is World War II remembered as "The Good War"? Despite the destruction, death, and devastation, the war helped usher in a new world order, one in which Hitler's Third Reich in Europe was no more, and some of history's most heinous crimes had been exposed and resisted. In the United States, wartime mobilization pulled the American economy out of depression, employing millions. American women and blacks experienced some freedoms unattainable in pre-war society. And on the world stage, the United States earned a new, powerful and coveted role.
World War II also marked the beginning of the end of world imperialism as nationalist movements began to triumph over weakened colonial empires. One by one, in the decades following the war, colonized peoples all over the world would gain their independence. In these ways, as historian Jay Winter has argued, 1945 marked the moment when the world broke from its past and moved toward a new era.1