As Americans celebrated “V.E.” (Victory in Europe) Day, they redirected their full attention to the still-raging Pacific War. As in Europe, the war in the Pacific started slowly. After Pearl Harbor, the American-controlled Philippine archipelago fell to Japan. After running out of ammunition and supplies, the garrison of American and Filipino soldiers surrendered. The prisoners were marched 80 miles to their prisoner of war camp without food, water, or rest. 10,000 died on the Bataan Death March.

But as Americans mobilized their armed forces, the tide turned. In the summer of 1942, American naval victories at the Battle of the Coral Sea Coral Sea and the aircraft carrier duel at the Battle of Midway crippled Japan’s Pacific naval operations. To dislodge Japan’s hold over the Pacific, the US military began island hopping: attacking island after island, bypassing the strongest but seizing those capable of holding airfields to continue pushing Japan out of the region. Combat was vicious. At Guadalcanal American soldiers saw Japanese soldiers launch suicidal charges rather than surrender. Many Japanese soldiers refused to be taken prisoner, and they refused to take prisoners. The war against Japan was fought with more brutality than the war against Germany.

Japanese defenders fought tenaciously. Few battles were as one-sided as the Battle of the Philippine Sea, or what the Americans called the Japanese counterattack “The Great Marianas Turkey Shoot.” Japanese soldiers bled the Americans in their advance across the Pacific. At Iwo Jima, an eight-square-mile island of volcanic rock, 17,000 Japanese soldiers held the island against 70,000 marines for over a month. At the cost of nearly their entire force, they inflicted almost 30,000 casualties before the island was lost.

By February 1945, American bombers were in range of the mainland. Bombers hit Japan’s industrial facilities but suffered high casualties. To spare bomber crews from dangerous daylight raids, and to achieve maximum effect against Japan’s wooden cities, many American bombers dropped incendiary weapons that created massive fire storms and wreaked havoc on Japanese cities. Over sixty Japanese cities were fire-bombed. American fire bombs killed 100,000 civilians in Tokyo in March 1945.

In June 1945, after eighty days of fighting and tens of thousands of casualties, the Americans captured the island of Okinawa. The mainland of Japan was open before them. It was a viable base from which to launch a full invasion of the Japanese homeland and end the war.

Estimates varied but, given the tenacity of Japanese soldiers in islands far from their home, some officials estimating that an invasion of the mainland could half-million American casualties and perhaps millions of Japanese civilians. These would be the numbers used later to justify the use of atomic weapons.

Early in the war, fearing that the Germans might develop an atomic bomb, the U.S. government launched the Manhattan Project, a hugely expensive, ambitious program to harness atomic energy and create a single weapon capable of leveling entire cities. The Americans successfully exploded the world’s first nuclear device, Trinity, in New Mexico in July 1945. Two more bombs—“Fat Man” and “Little Boy”—were built and detonated over two Japanese cities. Hiroshima was hit on August 6^th. Over 100,000 civilians were killed. Nagasaki followed on August 9^th. Perhaps 80,000 civilians were killed.

Emperor Hirohito announced the surrender of Japan on August 14^th. The following day, aboard the battleship USS Missouri, delegates from the Japanese government formally signed their surrender. World War II was finally over.