Everything changed after the atomic bombings of Hiroshima and Nagasaki and the Soviet declaration of war. And on August 10, the cabinet drafted an "Imperial Rescript ending the War" following the Emperor's indications that the declaration did not compromise any demand which prejudiced the prerogatives of His Majesty as a Sovereign Ruler.
On August 12, 1945, the Emperor informed the imperial family of his decision to surrender. One of his uncles, Prince Yasuhiko Asaka, asked whether the war would be continued if the kokutai (national polity) could not be preserved. The Emperor simply replied "Of course."
A faction of the army opposed to the surrender attempted a coup d'état on the evening of 14 August, prior to the broadcast. They seized the Imperial Palace (the Kyūjō incident), but the physical recording of the emperor's speech was hidden and preserved overnight. The coup was crushed by the next morning, and the speech was broadcast.
In less than two weeks the Kwantung Army, which was the primary Japanese fighting force,consisting of over a million men but lacking in adequate armor, artillery, or air support, had been destroyed by the Soviets. Japanese Emperor Hirohito officially capitulated to the Allies on August 15, 1945.
In addition to the bombing of the two bombings, the Soviets, pursuant to the Yalta agreement, invaded Japanese-held Manchuria and quickly defeated the Kwantung Army, which was the largest Japanese fighting force, These two events persuaded previously adamant Imperial Army leaders to accept surrender terms. The Red Army also captured the southern part of Sakhalin Island and the Kuril Islands. On 15 August 1945, Japan surrendered.
On August 15 a recording of the Emperor's surrender speech ("Gyokuon-hōsō", literally "Jewel Voice Broadcast") was broadcast over the radio (the first time the Emperor was heard on the radio by the Japanese people) announcing Japan's acceptance of the Potsdam Declaration. During the historic broadcast the Emperor stated: "Moreover, the enemy has begun to employ a new and most cruel bomb, the power of which to do damage is, indeed, incalculable, taking the toll of many innocent lives. Should we continue to fight, not only would it result in an ultimate collapse and obliteration of the Japanese nation, but also it would lead to the total extinction of human civilization.