The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, ending the war. By the end of July 1945, the Imperial Japanese Navy (IJN) was incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of Japan in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction".
While publicly stating their intent to fight on to the bitter end, Japan's leaders (the Supreme Council for the Direction of the War, also known as the "Big Six") were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea (in addition to South Sakhalin and the Kuril Islands) in fulfillment of promises they had secretly made to the US and the UK at the Tehran and Yalta Conferences.
On 6 August 1945, at 8:15 am local time, the United States detonated an atomic bomb over the Japanese city of Hiroshima. Sixteen hours later, American president Harry S. Truman called again for Japan's surrender, warning them to "expect a rain of ruin from the air, the like of which has never been seen on this earth." Late on 8 August 1945, in accordance with the Yalta agreements, but in violation of the Soviet–Japanese Neutrality Pact, the Soviet Union declared war on Japan, and soon after midnight on 9 August 1945, the Soviet Union invaded the Japanese puppet state of Manchuria. Hours later, the U.S. dropped a second atomic bomb on the Japanese city of Nagasaki.
Emperor Hirohito subsequently ordered the Supreme Council for the Direction of the War to accept the terms the Allies had set down in the Potsdam Declaration. After several more days of behind-the-scenes negotiations and a failed coup d'état by hardliners in the Japanese military, Emperor Hirohito gave a recorded radio address across the Empire on 15 August announcing the surrender of Japan to the Allies.
On 28 August, the occupation of Japan began, led by the Supreme Commander for the Allied Powers. The formal surrender ceremony was held on 2 September, aboard the U.S. Navy battleship USS Missouri, at which officials from the Japanese government signed the Japanese Instrument of Surrender, ending hostilities with the Allies. Allied civilians and military personnel alike celebrated V-J Day, the end of the war in the Pacific; however, isolated soldiers and other personnel from Japan's forces scattered throughout Asia and the Pacific refused to surrender for months and years afterwards, some into the 1970s. The role of the atomic bombings in Japan's unconditional surrender, and the ethics of the two attacks, is debated. The state of war formally ended when the Treaty of San Francisco came into force on 28 April 1952. Four years later, Japan and the Soviet Union signed the Soviet–Japanese Joint Declaration of 1956, formally ending their state of war.
Background
By 1945, the Japanese had suffered a string of defeats for nearly two years in the South West Pacific, India, the Marianas campaign, and the Philippines campaign. In July 1944, following the loss of Saipan, General Hideki Tōjō was replaced as prime minister by General Kuniaki Koiso, who declared that the Philippines would be the site of the decisive battle. After the Japanese loss of the Philippines, Koiso in turn was replaced by Admiral Kantarō Suzuki. The Allies captured the nearby islands of Iwo Jima and Okinawa in the first half of 1945. Okinawa was to be a staging area for Operation Downfall, the Allied invasion of the Japanese Home Islands. Following Germany's defeat, the Soviet Union began quietly redeploying its battle-hardened forces from the European theatre to the Far East, in addition to about forty divisions that had been stationed there since 1941, as a counterbalance to the million-strong Kwantung Army.
The Allied submarine campaign and the mining of Japanese coastal waters had largely destroyed the Japanese merchant fleet. With few natural resources, Japan was dependent on raw materials, particularly oil, imported from Manchuria and other parts of the East Asian mainland, and from the conquered territory in the Dutch East Indies. The destruction of the Japanese merchant fleet, combined with the strategic bombing of Japanese industry, had wrecked Japan's war economy. Production of coal, iron, steel, rubber, and other vital supplies was only a fraction of that before the war.
As a result of the losses it had suffered, the Imperial Japanese Navy (IJN) had ceased to be an effective fighting force. Following a series of raids on the Japanese shipyard at Kure, the only major warships in somewhat fighting order were six aircraft carriers, four cruisers, and one battleship, of which many were heavily damaged and none could be fueled adequately. Although 19 destroyers and 38 submarines were still operational, their use was also limited by the lack of fuel.
Defense preparations
Faced with the prospect of an invasion of the Home Islands, starting with Kyūshū, and the prospect of a Soviet invasion of Manchuria—Japan's last source of natural resources—the War Journal of the Imperial Headquarters concluded in 1944:
We can no longer direct the war with any hope of success. The only course left is for Japan's one hundred million people to sacrifice their lives by charging the enemy to make them lose the will to fight.
As a final attempt to stop the Allied advances, the Japanese Imperial High Command planned an all-out defense of Kyūshū codenamed Operation Ketsugō. This was to be a radical departure from the defense in depth plans used in the invasions of Peleliu, Iwo Jima, and Okinawa. Instead, everything was staked on the beachhead; more than 3,000 kamikazes would be sent to attack the amphibious transports before troops and cargo were disembarked on the beach.
If this did not drive the Allies away, they planned to send another 3,500 kamikazes along with 5,000 Shin'yō suicide motorboats and the remaining destroyers and submarines—"the last of the Navy's operating fleet"—to the beach. If the Allies had fought through this and successfully landed on Kyūshū, 3,000 planes would have been left to defend the remaining islands, although Kyūshū would be "defended to the last" regardless. The strategy of making a last stand at Kyūshū was based on the assumption of continued Soviet neutrality.
Supreme Council for the Direction of the War
Japanese policy-making centered on the Supreme Council for the Direction of the War (created in 1944 by earlier Prime Minister Kuniaki Koiso), the so-called "Big Six"—the Prime Minister, Minister of Foreign Affairs, Minister of the Army, Minister of the Navy, Chief of the Army General Staff, and Chief of the Navy General Staff. At the formation of the Suzuki government in April 1945, the council's membership consisted of:
All of these positions were nominally appointed by the Emperor and their holders were answerable directly to him. Nevertheless, Japanese civil law from 1936 required that the Army and Navy ministers had to be active duty flag officers from those respective services while Japanese military law from long before that time prohibited serving officers from accepting political offices without first obtaining permission from their respective service headquarters which, if and when granted, could be rescinded at any time. Thus, the Japanese Army and Navy effectively held a legal right to nominate (or refuse to nominate) their respective ministers, in addition to the effective right to order their respective ministers to resign their posts.
Strict constitutional convention dictated (as it technically still does today) that a prospective Prime Minister could not assume the premiership, nor could an incumbent Prime Minister remain in office, if he could not fill all of the cabinet posts. Thus, the Army and Navy could prevent the formation of undesirable governments, or by resignation bring about the collapse of an existing government.
Emperor Hirohito and Lord Keeper of the Privy Seal Kōichi Kido also were present at some meetings, following the Emperor's wishes. Iris Chang reports that the Japanese destroyed, hid or falsified most of their secret wartime documents before General MacArthur arrived."
Japanese leadership divisions
For the most part, Suzuki's military-dominated cabinet favored continuing the war. For the Japanese, surrender was unthinkable—Japan had never been successfully invaded or lost a war in its history. Only Mitsumasa Yonai, the Navy minister, was known to desire an early end to the war. According to historian Richard B. Frank:
Although Suzuki might indeed have seen peace as a distant goal, he had no design to achieve it within any immediate time span or on terms acceptable to the Allies. His own comments at the conference of senior statesmen gave no hint that he favored any early cessation of the war ... Suzuki's selections for the most critical cabinet posts were, with one exception, not advocates of peace either.
After the war, Suzuki and others from his government and their apologists claimed they were secretly working towards peace, and could not publicly advocate it. They cite the Japanese concept of haragei—"the art of hidden and invisible technique"—to justify the dissonance between their public actions and alleged behind-the-scenes work. However, many historians reject this. Robert J. C. Butow wrote:
Because of its very ambiguity, the plea of haragei invites the suspicion that in questions of politics and diplomacy a conscious reliance upon this 'art of bluff' may have constituted a purposeful deception predicated upon a desire to play both ends against the middle. While this judgment does not accord with the much-lauded character of Admiral Suzuki, the fact remains that from the moment he became Premier until the day he resigned no one could ever be quite sure of what Suzuki would do or say next.
Japanese leaders had always envisioned a negotiated settlement to the war. Their prewar planning expected a rapid expansion and consolidation, an eventual conflict with the United States, and finally a settlement in which they would be able to retain at least some new territory they had conquered. By 1945, Japan's leaders were in agreement that the war was going badly, but they disagreed over the best means to negotiate its end. There were two camps: the so-called "peace" camp favored a diplomatic initiative to persuade Joseph Stalin, the leader of the Soviet Union, to mediate a settlement between the Allies and Japan; and the hardliners who favored fighting one last "decisive" battle that would inflict so many casualties on the Allies that they would be willing to offer more lenient terms. Both approaches were based on Japan's experience in the Russo–Japanese War, forty years earlier, which consisted of a series of costly but largely indecisive battles, followed by the decisive naval Battle of Tsushima.
In February 1945, Prince Fumimaro Konoe gave Emperor Hirohito a memorandum analyzing the situation, and told him that if the war continued, the imperial family might be in greater danger from an internal revolution than from defeat. According to the diary of Grand Chamberlain Hisanori Fujita, the Emperor, looking for a decisive battle (tennōzan), replied that it was premature to seek peace "unless we make one more military gain". Also in February, Japan's treaty division wrote about Allied policies towards Japan regarding "unconditional surrender, occupation, disarmament, elimination of militarism, democratic reforms, punishment of war criminals, and the status of the emperor." Allied-imposed disarmament, Allied punishment of Japanese war criminals, and especially occupation and removal of the Emperor, were not acceptable to the Japanese leadership.
On 5 April, the Soviet Union gave the required 12 months' notice that it would not renew the five-year Soviet–Japanese Neutrality Pact (which had been signed in 1941 following the Nomonhan Incident). Unknown to the Japanese, at the Tehran Conference in November–December 1943, it had been agreed that the Soviet Union would enter the war against Japan once Germany was defeated. At the Yalta Conference in February 1945, the United States had made substantial concessions to the Soviets to secure a promise that they would declare war on Japan within three months of the surrender of Germany. Although the five-year Neutrality Pact did not expire until 5 April 1946, the announcement caused the Japanese great concern, because Japan had amassed its forces in the South to repel the inevitable US attack, thus leaving its Northern islands vulnerable to Soviet invasion. Soviet Foreign Minister Vyacheslav Molotov, in Moscow, and Yakov Malik, Soviet ambassador in Tokyo, went to great lengths to assure the Japanese that "the period of the Pact's validity has not ended".
At a series of high-level meetings in May, the Big Six first seriously discussed ending the war, but none of them on terms that would have been acceptable to the Allies. Because anyone openly supporting Japanese surrender risked assassination by zealous army officers, the meetings were closed to anyone except the Big Six, the Emperor, and the Privy Seal. No second or third-echelon officers could attend. At these meetings, despite the dispatches from Japanese ambassador Satō in Moscow, only Foreign Minister Tōgō realized that Roosevelt and Churchill might have already made concessions to Stalin to bring the Soviets into the war against Japan. Tōgō had been outspoken about ending the war quickly. As a result of these meetings, he was authorized to approach the Soviet Union, seeking to maintain its neutrality, or (despite the very remote probability) to form an alliance.
In keeping with the custom of a new government declaring its purposes, following the May meetings the Army staff produced a document, "The Fundamental Policy to Be Followed Henceforth in the Conduct of the War," which stated that the Japanese people would fight to extinction rather than surrender. This policy was adopted by the Big Six on 6 June. (Tōgō opposed it, while the other five supported it.) Documents submitted by Suzuki at the same meeting suggested that, in the diplomatic overtures to the USSR, Japan adopt the following approach:
It should be clearly made known to Russia that she owes her victory over Germany to Japan, since we remained neutral, and that it would be to the advantage of the Soviets to help Japan maintain her international position, since they have the United States as an enemy in the future.