Project TRINITY was the name given to the war-time effort to produce
the first nuclear detonation. A plutonium-fueled implosion device was
detonated on 16 July 1945 at the Alamogordo Bombing Range in
south-central New Mexico.

Three weeks later, on 6 August, the first uranium-fueled nuclear bomb,
a gun-type weapon code-named LITTLE BOY, was detonated over the
Japanese city of Hiroshima. On 9 August, the FAT MAN nuclear bomb, a
plutonium-fueled implosion weapon identical to the TRINITY device, was
detonated over another Japanese city, Nagasaki. Two days later, the
Japanese Government informed the United States of its decision to end
the war. On 2 September 1945, the Japanese Empire officially
surrendered to the Allied Governments, bringing World War II to an
end.

In the years devoted to the development and construction of a nuclear
weapon, scientists and technicians expanded their knowledge of nuclear
fission and developed both the gun-type and the implosion mechanisms
to release the energy of a nuclear chain reaction. Their knowledge,
however, was only theoretical. They could be certain neither of the
extent and effects of such a nuclear chain reaction, nor of the
hazards of the resulting blast and radiation. Protective measures
could be based only on estimates and calculations. Furthermore,
scientists were reasonably confident that the gun-type uranium-fueled
device could be successfully detonated, but they did not know if the
more complex firing technology required in an implosion device would
work. Successful detonation of the TRINITY device showed that
implosion would work, that a nuclear chain reaction would result in a