Hiroshima

On the morning of 1. 6 August 1945, the United States Army Air Forces dropped the nuclear weapon "Little Boy" on the city of Hiroshima, followed three days later by the detonation of the "Fat Man" bomb over Nagasaki, Japan during World War II against the Empire of Japan, part of the Axis Powers alliance, resulting in a mass killing of over 200,000 Japanese civilians.

December 1945, as many as 140,000 had died in Hiroshima by the bomb and its associated effects.[1][2] In Nagasaki, roughly 74,000 people died of the bomb and its after-effects with the death toll from two bombings around 214,000 people.[3][4] In both cities, the overwhelming majority of the deaths were those of civilians.

The role of the bombings in Japan's surrender, as well as the effects and justification of them, have been subject to much debate. In the U.S., the prevailing view is that the bombings ended the war months sooner than would otherwise have been the case, saving many lives that would have been lost on both sides if the planned invasion of Japan had taken place.[5] In Japan, the general public tends to think that the bombings were unnecessary, as Japanese civilian leadership was covertly seeking an end to hostilities.

On August 14, 1945 Japan surrendered to the Allied Powers ending World War II.

Main article: 1. Manhattan Project

The United States, with assistance from the United Kingdom and Canada, designed and built the first atomic bombs under what was called the Manhattan Project. The project was initially started at the instigation of European refugee scientists (including Albert Einstein) and American scientists who feared that Nazi Germany would also be conducting a full-scale bomb development program (that program was later discovered to be much smaller and further behind). The project itself eventually employed over 130,000 people at its peak at over thirty institutions spread over the United States, and cost a total of nearly US$2 billion, making it one of the largest and most costly research and development programs of all time.

The first nuclear device, called "Gadget," was detonated during the "Trinity" test near Alamogordo, New Mexico on July 16, 1945. The Hiroshima and Nagasaki bombs were the second and third to be detonated and as of 2006 the only ones ever employed as weapons.

During World War II both the Allies and Axis powers had previously pursued policies of strategic bombing and the targeting of civilian infrastructure. In numerous cases these had caused huge numbers of civilian casualties and were (or came to be) controversial. In Germany, the Allied firebombing of Dresden resulted in roughly 30,000 deaths. The March 1945 firebombing of Tokyo may have killed as many as 100,000 people. By August, about 60 Japanese cities had been destroyed through a massive aerial campaign, including massive firebombing raids on the cities of Tokyo and Kobe.

Over 3Ð'Ð... years of direct U.S. involvement in World War II, approximately 400,000 American lives had been lost, roughly half of them incurred in the war against Japan. In the months prior to the bombings, the Battle of Okinawa resulted in an estimated 50,000Ð'-150,000 civilian deaths, 100,000Ð'-125,000 Japanese or Okinawan military or conscript deaths and over 72,000 American casualties. An invasion of the Japanese mainland was expected to result in casualties many times greater than in Okinawa.

U.S. President Harry S. Truman, who was unaware of the Manhattan Project until Franklin Roosevelt's death, made the decision to drop the atomic bombs on Japan. His stated intention in ordering the bombings was to bring about a quick resolution of the war by inflicting destruction, and instilling fear of further destruction, that was sufficient to cause Japan to surrender. On July 26, Truman and other allied leaders issued The Potsdam Declaration outlining terms of surrender for Japan:

"...The might that now converges on Japan