As 1945 opened, Allied victory was assured. In December 1944, in a desperate gamble, Hitler launched a surprise counterattack in France that pushed Allied forces back fifty miles, creating a large bulge in their lines. The largest single battle ever fought by the U.S. Army, the Battle of the Bulge produced more than 70,000 American casualties. But by early 1945 the assault had failed.
In March, American troops crossed the Rhine River and entered the industrial heartland of Germany. Hitler took his own life, and shortly afterward Soviet forces occupied Berlin. On May 8, known as V-E Day (for victory in Europe), came the formal end to the war against Germany. In the Pacific, American forces moved ever closer to Japan. They had reconquered Guam in August 1944 and landed in the Philippines two months later, where they destroyed most of the remainder of the enemy fleet in the naval battle of Leyte Gulf.
Franklin D. Roosevelt defeated Republican nominee Thomas E. Dewey, the governor of New York, to win an unprecedented fourth term in 1944. But FDR did not live to see the Allied victory. He succumbed to a stroke on April 12, 1945. To his successor, Harry S. Truman, fell one of the most momentous decisions ever confronted by an American president—whether to use the atomic bomb against Japan. Truman did not know about the bomb until after he became president. Then, Secretary of War Stimson informed him that the United States had secretly developed “the most terrible weapon ever known in human history.”
The bomb was a practical realization of the theory of relativity, a rethinking of the laws of physics developed early in the twentieth century by the German scientist Albert Einstein. Energy and matter, Einstein showed, represented two forms of the same phenomenon. According to his famous equation E = me2, the energy contained in matter equals its mass times the speed of light squared—an enormous amount. By using certain forms of uranium, or the man-made element plutonium, an atomic reaction could be created that transformed part of the mass into energy. This energy could be harnessed to provide a form of controlled power, or it could be unleashed in a tremendous explosion.
Having fled to the United States from Hitler’s Germany, Einstein in 1939 warned Roosevelt that Nazi scientists were trying to develop an atomic weapon and urged the president to do likewise. In the following year, FDR authorized what came to be known as the Manhattan Project, a top-secret program in which American scientists developed an atomic bomb during World War II. The weapon was tested successfully in New Mexico in July 1945.
On August 10, 1945, the day after the detonation of the atomic bomb over Nagasaki, the Japanese photographer Yosuke Yamahata captured this image of dazed survivors in the devastated city.