Groves. Special acknowledgement to those whose work contributed
largely to this report is made to:

The Special Manhattan Engineer District Investigating Group,
The United States Strategic Bombing Survey,
The British Mission to Japan, and

The Joint Atomic Bomb Investigating Group (Medical). and particularly
to the following individuals:

Col. Stafford L. Warren, Medical Corps, United States Army, for his
evaluation of medical data,

Capt. Henry L. Barnett, Medical Corps, United States Army, for his
evaluation of medical data,

Dr. R. Serber, for his comments on flash burn,

Dr. Hans Bethe, Cornell University, for his information of the nature
of atomic explosions,

Majors Noland Varley and Walter C. Youngs, Corps of Engineers, United
States Army, for their evaluation of physical damage to structures,

J. 0. Hirschfelder, J. L. Magee, M. Hull, and S. T. Cohen, of the Los
Alamos Laboratory, for their data on nuclear explosions,

Lieut. Col. David B. Parker, Corps of Engineers, United States Army,
for editing this report.

INTRODUCTION

Statement by the President of the United States: "Sixteen hours ago an
American airplane dropped one bomb on Hiroshima, Japan, and destroyed
its usefulness to the enemy. That bomb had more power than 20,000 tons
of T.N.T. It had more than two thousand times the blast power of the
British Grand Slam, which is the largest bomb ever yet used in the
history of warfare".

These fateful words of the President on August 6th, 1945, marked the
first public announcement of the greatest scientific achievement in
history. The atomic bomb, first tested in New Mexico on July 16, 1945,
had just been used against a military target.

On August 6th, 1945, at 8:15 A.M., Japanese time, a B-29 heavy bomber
flying at high altitude dropped the first atomic bomb on Hiroshima.
More than 4 square miles of the city were instantly and completely
devastated. 66,000 people were killed, and 69,000 injured.

On August 9th, three days later, at 11:02 A.M., another B-29 dropped
the second bomb on the industrial section of the city of Nagasaki,
totally destroying 1 1/2 square miles of the city, killing 39,000
persons, and injuring 25,000 more.

On August 10, the day after the atomic bombing of Nagasaki, the
Japanese government requested that it be permitted to surrender under
the terms of the Potsdam declaration of July 26th which it had
previously ignored.

THE MANHATTAN PROJECT AT