[With Germany defeated, Allied strategists began repositioning men and materiel for a 1946 invasion of Japan's home islands, fully aware of the immense difficulties they would face. Then the use of a new weapon precluded such an invasion and induced Japan to end hostilities.]

(August 13, 1945)

A new era was born--the age of atomic force. Like many an epoch in man's progress toward civilization, it was wombed in war's destruction. The birth was announced one day this week by the President of the United States. His words:

"Sixteen hours ago an American airplane dropped one bomb on Hiroshima, an important Japanese army base. That bomb had more power than 20,000 tons of TNT...It is an atomic bomb. It is a harnessing of the basic power of the universe...What has been done is the greatest achievement of organized science in history..."

Thus to the U.S., already in military and scientific prowess, had come man's most destructive weapon.

The atomic bomb was something more than an instrument to shape 1945's history. It represented a brutal challenge to the world to keep the peace. The scientists had created, and had successfully applied, a weapon which might wipe out with a few strokes any nation's power to resist an enemy.

For scientists and laymen alike, this week's historic blast was the first indication of the progress made in the greatest and most-secret research race of the war. Except for a few breathless tales of mysterious walled laboratories and factories whose workers were interned for the duration, scarcely a word leaked out.

A host of famed scientists, including such bigwigs as Niels Bohr, Ernest Lawrence, Arthur Holly Compton and James B. Conant, were enlisted in it. Hidden under the official designation "Manhattan Project," the vast forbidden areas in Tennessee, Washington and New Mexico got top priorities not only a materiel but on scientific brains and effort.

Principal credit for the fruitful channeling of this rich source of brainpower, announced Secretary of War Stimson, belongs to "the genius and inspiration" of slight, dark Physicist J. Robert Oppenheimer, 41, of the University of California and California Institute of Technology. Long a vanguard authority on atomic structure, he is, says his colleagues, "one of the world's greatest geniuses, no question about it."

The Stretch. When in March 1941, the process was discovered for manufacturing the atomic explosive, chemists feared it would take years to perfect a method of making it in quantity.

But last July 12, the scientists were ready to test their product. In an old ranch house on the New Mexican desert southeast of Albuquerque, a company of jittery men watched Cornell Physicist Robert Bacher assemble the first atomic bomb.

Thunder & lightning rumbled and flashed in the early morning of July 16 when the final test was to be made. The bomb was carefully mounted on a steel tower hung with instruments to record the effects of the explosion. Over five miles away, the scientists lay flat, listening breathlessly to the time signals. At "minus 45 seconds" a robot mechanism took over the controls and the watchers lived the tensest seconds of their lives.

Suddenly there was a tremendous sustained roar. In Albuquerque, 120 miles away, the sky blazed noonday-bright. The scientists close at hand looked up in time to see a huge, multicolored pillar of cloud surging up over 40,000 feet in the sky. But where the steel tower stood, there was only a crater. The tower had completely vaporized.

[The Japanese surrendered on August 14. Two weeks later, the instruments of surrender were formally signed aboard the U.S.S. Missouri.]

(September 10, 1945)

TIME Correspondent Theodore H. White cabled:

"The Japanese had been piped aboard four minutes before MacArthur made his appearance: Japanese Foreign Minister Mamoru Shigemitsu, limping on his wooden leg, solemn-faced Chief of the Imperial General Staff, Yoshijiro Umezu.

"Complete silence greeted them as they ascended the deck. The American generals watched them come to attention in their designated places with varying degrees of emotion.

"MacArthur stepped out from a cabin, stood stiffly erect and began reading with all the mellifluous, sonorous qualities of his magnificent voice. The only sign of his emotion was the trembling of the hands in which he held his paper.

"As he closed the introductory remarks he half turned and faced the Japs with a piercing stare and said: `I announced it my firm purpose...to insure that the terms of surrender are fully, promptly and faithfully complied with.'

"Shigemitsu, doffing his silk hat and peeling a yellow glove from his right hand, limped forward to sign the document and was assisted to a chair. Umezu followed.

"In almost unbroken silence the ship's crew assembled as witnesses and watched one delegate after another affix their signatures. Grey, overcast skies had hung over the ship all during the ceremony. As the New Zealand delegate stepped forward to sign his name as the last on the list, the skies parted and the sun shone bright through the clouds.

"MacArthur stepped forward and said slowly `Let us pray that peace be now restored to the world and that God will preserve it always.'

"He lifted his eyes from the script, faced the Japanese, and declared: `These proceedings are closed.'

"As the Japs departed, grey skies closed in again on the grey ships, and there was a steady drone in the sky. The drone became a deafening roar, and a mass of U.S. planes swept over the ships--400 B29s and 1,500 fleet carrier planes--in a final salute. Then it was quiet again. The ceremony--and the war--were over."