After Pearl Harbor, Japan won a string of victories: the Philippines, where thousands of American and Filipino prisoners died on the Bataan Death March (1942), Guam, Wake, Hong Kong, Singapore and the Dutch East Indies. The U.S. fought back across the largest ocean on Earth.
Key idea
After the turning point at Midway (June 1942), U.S. forces "island hopped" toward Japan (Guadalcanal, Iwo Jima, Okinawa). Atomic bombs struck Hiroshima (August 6, 1945) and Nagasaki (August 9). Japan announced its surrender August 15 and signed it September 2, 1945.
Why it works
At Midway, American code breakers learned of Japan's plan, and U.S. planes sank four Japanese aircraft carriers in one battle; Japan never regained the initiative. Island hopping meant seizing key islands for airfields and bases while bypassing others, cutting them off. Each step closer to Japan cost more: at Iwo Jima nearly 7,000 Americans were killed, and at Okinawa about 12,000, with far greater Japanese military and civilian losses. Meanwhile the secret Manhattan Project built an atomic bomb, first tested in New Mexico on July 16, 1945. President Harry Truman, who had taken office in April, approved its use after Japan rejected the Allies' call for unconditional surrender.
The bombs killed about 140,000 people in Hiroshima and about 70,000 in Nagasaki by the end of 1945. On August 8 the Soviet Union declared war on Japan. On August 15 Emperor Hirohito announced Japan would surrender; the formal surrender was signed aboard the USS Missouri on September 2.
| Argument for the decision | Argument against |
|---|---|
| An invasion of Japan, planned for late 1945, could have cost hundreds of thousands of American lives and many more Japanese | Japan was already weakened by blockade and bombing, and might have surrendered without the bombs |
| Okinawa and Iwo Jima showed how fiercely Japan would fight | The Soviet entry into the war, or a promise to keep the emperor, might have brought surrender |
| The bombs ended the war quickly, before more of Asia suffered | A demonstration on an empty area might have been tried; the bombs killed vast numbers of civilians |
Work it through
Worked example: Order the final weeks
Order: Japan announces surrender; Nagasaki; the Soviet Union declares war on Japan; Hiroshima.
- Hiroshima: August 6.
- Soviet declaration of war: August 8.
- Nagasaki: August 9.
- Surrender announced: August 15 (signed September 2).
Answer: Hiroshima, Soviet entry, Nagasaki, surrender.
Common mistake
Students often present the decision to use the bomb as settled one way or the other. Historians debate it: supporters stress the lives an invasion would have cost; critics point to Japan's weakening position and other options. Practice questions here ask what each side argues, not which is right.