On August 6, 1945, during World War II, US President Harry Truman took the decision to drop an atomic bomb, coded the Little Boy, over Hiroshima, Japan.

On that morning American commander Colonel Paul Tibbets (who was posted briefly in India in the 1960s as a military attache till protests ousted him) took off from a base in the Mariana Islands in the west Pacific, flying a B-29 named Enola Gay after his mom. At 08.15, Japanese local time, a nuclear device carrying 60 kilos of uranium was dropped from Enola Gay as Tibbets flew over Hiroshima. It took just 57 seconds to fall and create unforgettable mayhem.

More than 90,000 were killed instantly and thousands more subsequently.

At the time the US and the other allied powers were at war with the Empire of Japan.

Hiroshima in southern Japan was considered a prime target for an atomic bomb attack, although Kyoto and Yokohoma were suggested too, because it had not suffered any other type of bombing earlier, it was an enormous population centre (255,000) and the location of a very large arms arsenal and army base; it had no POW camps either. The mountains surrounding Hiroshima would make sure the bomb had tremendous impact. Second choice was Kokura where an arsenal was located and third the large port town of Nagasaki.

Japanese radar systems that fateful morning detected the arrival of Enola Gay and its outrider planes. But it was already the fourth year of the war and Japanese defence systems were not up to repulsing just a few planes and were saving their fire for larger attacks. Citizens were merely informed abut the possibility of an impending attack -- a signal to flee to air raid shelters.

A few minutes later Hiroshima went completely off everyone's radar.

A surveillance plane was sent from the army base in Tokyo to find out what could be wrong; although they did not suspect much.

As the pilot and co-pilot came within 100 km of Hiroshima they saw that giant mushroom cloud and realised Hiroshima had been annihilated and immediately initiated rescue operations.

Before the extent of the disaster had even sunk into a shocked Japan, America quickly broadcast details of the destruction to the rest of the world. President Truman announced: 'If they do not accept our terms, they may expect a rain of ruin from the air the likes of which has never been seen on this earth'.

And three days later Truman followed it up with the Fat Man, a second atomic bomb, over Nagasaki killing some 74,000 more.

Japan surrendered six days after that on August 15 and World War II came to an end (Germany had already surrendered in Berlin on May 2).

This was the first and only time a nuclear device was employed in warfare.

And in the 62 years that have passed since, ceremonies remembering the events of that terrible day have always had a special importance across the world.

It is a moment to remember the kind of damage that irresponsible use of a nuclear weapon brings.

Image: Japanese Prime Minister Shinzo Abe offers silent prayers and a wreath at the Hiroshima Peace Memorial Ceremony on Monday in Hiroshima.

Photograph: Getty Images

Earlier slide show: The death ships

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