The Allies Issue an Ultimatum for Japan's Surrender: July 26, 1945

This text comes from our book, The American Venture.

While the German war power was crumbling in Europe, American forces were clearing the Pacific of Japanese resistance. From the island of Saipan, American bombing raids struck Japanese cities, destroying industrial targets and killing tens of thousands of Japanese civilians. The U.S. firebombing of Tokyo destroyed 16 square miles of the city, killing up to 100,000 people. On February 19, 1945, American forces, landing on the island of Iwo Jima, began a bloody battle that would continue until March 26. In the invasion of Okinawa island in the Ryukyus, American forces suffered heavy losses. Japanese kamikaze raids sank 32 ships, badly damaged 61 others, and killed over 12,500 American sailors, soldiers, and aviators. The American invasion that had begun on Easter Sunday, April 1, 1945, did not overwhelm Japanese resistance until late June. 

As in Europe, the Allies demanded nothing short of unconditional surrender from the Japanese. This policy meant that the Allies faced the prospect of a land invasion of Japan that would likely result in the deaths of tens of thousands of Allied soldiers, as well as of countless civilians. The Allies either had to abandon the policy or find some other means to avoid the grim prospects of an invasion. But what other way did they have?

The theater of war around Japan, 1945

The United States had the means to bring Japan to its knees. Even the former vice president, Harry Truman, did not learn of it until he became president after Roosevelt’s death—a new, secret weapon of extraordinary destructive capacity. From a number of physicists, including the German Jew Albert Einstein, the Italian Enrico Fermi, and the Hungarian Leó Szilárd, Roosevelt had learned that German scientists were working on the concept of uranium fission to produce a bomb that could wipe out large sections of cities. In what was called the Manhattan Project, the U.S. began working on the splitting of the atom to develop such a bomb before the Germans did. By 1944, at the laboratories at Los Alamos, New Mexico, the physicist, J. Robert Oppenheimer, had developed the first atomic bomb. On July 16, 1945, this atomic bomb was successfully exploded at Los Alamos. The United States now possessed a weapon that the broken but desperate might of Japan could not withstand. President Truman called it “the Second Coming in wrath.”

With advice from high government officials and atomic scientists, President Truman decided that, if Japan did not agree to an unconditional surrender by August 3, the U.S. should drop two atomic bombs on the mainland of Japan as soon as possible.

On July 26, the Allies issued their ultimatum: Japan must surrender without conditions, give up all lands she had conquered since 1895, and allow Allied occupation of the Japanese homeland until “a peacefully inclined and responsible government” be established. If this ultimatum is refused, said the Allies, “the alternative for Japan is prompt and utter destruction.” No assurance was given to the fulfillment of Japan’s one remaining demand—that the Emperor Hirohito (whom the Japanese considered divine) remain on the throne.

Japan’s reply to the Potsdam ultimatum was, “no comment.”

Three days after Japan’s surrender deadline, on August 6, 1945, the feast of Christ’s transfiguration, a U.S. B-29 bomber, the Enola Gay, set out for an expedition over the Japanese city of Hiroshima. The crew knew their plane carried a new sort of bomb (“The Gimmick,” they called it), but that is all they knew. When, just before 9:15 a.m., they dropped the bomb over Hiroshima, the shock of it and the blinding light it emitted filled them with awe. The next entry in the plane’s log after the explosion was two words: “My God.”

When Truman heard the news, he rejoiced. “This is the greatest thing in history,” he said.

Ruins of Nagasaki after the bombing. The Catholic cathedral rises in the background.

The atomic bomb that struck Hiroshima leveled four square miles of the city and killed 60,175 people—soldiers of the second Japanese army, men, women, the old, and children. Many more would die of radiation poisoning in the weeks and months following the explosion. On August 9, the United States dropped the second atomic bomb on nearby Nagasaki, a city with no military significance. Nagasaki was the Catholic center of Japan; ground zero was near the Catholic cathedral. Thirty-six thousand civilians died in this terror bombing.

With such destructive capacity in its enemy’s hands, Japan surrendered unconditionally on August 14, 1945. The formal act of surrender, signed aboard the U.S.S. Missouri on September 2, ended the Second World War.