Three days later the US dropped a second, bigger bomb at Nagasaki killing nearly 74,000 people and injuring tens of thousands.

US President Harry S Truman warned the Japanese they would face a "rain of ruin from the air" if they did not surrender.

The unconditional surrender signed on 14 August 1945, brought an end the six years of World War II.

Here is a selection of your memories:

Although too young to have been a witness to these terrible events, I always remember meeting an old Japanese soldier who said that the whole population of Japan would rather die fighting an invader than surrender.

Looking at the numbers, that means that although the decision to drop the atomic bombs had awful consequences, it was by far the lesser of two evils.
John Downe, Bahrain

My Father was a crewman on the USS Tyrrell, which participated in the Okinawa invasion and later transported the 2nd Marine Division to Nagasaki for the occupation.

During the Okinawa campaign he witnessed relentless kamikaze attacks spanning several days, and his ship was crashed by a Betty bomber which failed to explode.

He was on his ship in Majuro, preparing to support an assault on the Japanese mainland when news of the atomic bombings came through. He thought that while the infrastructure and industrial capacity of Japan may have been ruined, the army was committed to and capable of suicidal resistance to the end.

While the atomic bombings were horrible, only something that terrible compelled the Japanese leadership to finally admit defeat and capitulate.

A hastened surrender saved many Allied soldiers and sailors, POWs, Chinese civilians under Japanese rule, and ultimately many more Japanese than if capitulation had been forced by an invasion or blockade of the home islands.
B Coffyn, Virginia, USA

The people who ordered the attack and the people who are behind such bomb building - remember their souls will not rest forever.
Yasir, Japan

I've never seen an atomic bomb dropped on a city, a person eaten alive by radiation, or the graves of those whose lives were ended in an incinerating instant.

I'm not a descendant of veterans - my mother's father wasn't drafted because he had seven fingers, my father's father for reasons I don't know.

I've never seen war, only certain "police actions".

But I believe ever so firmly in my heart that war is not the greatest evil. And every veteran I have ever spoken to has told me that war is not the greatest evil. It is an abomination, yes, but there are far worse things.

It is far worse for one culture to label another as inferior, inhuman, and wipe them out because of it.

It is far worse for one nation to think they deserve total hegemony over the world, and strive with everything they have to attain that end.

It is far worse to snuff out millions of lives in battle only to reveal afterward that beforehand you had a weapon that could have prevented such staggering loss, a weapon that, while horrific in is capability, is a saviour in its use.

We dropped the atomic bombs on Hiroshima and Nagasaki, and while we mourn for those families lost in the blaze, I am thankful that we do not mourn for the fathers who spent their lives for a great cause, but spent them needlessly on the beaches and city streets of Japan.
Thomas Beard, USA

When I woke on the morning of 6 August, 2005 I was reminded that at that moment, sixty years previously, I had been sleeping under canvas in a field in Ware, Hertfordshire, a child of fifteen.

It was the day that I heard of the dropping of the first Atom bomb on Hiroshima. I heard the news on a tiny crystal wireless set to which was attached three pairs of massive headphones. Well, massive compared to today's tiny equivalent.

I suppose it's much like the reports of the Kennedy assassination, most of us who were around can remember the circumstances when we heard the news.

I would like to say that I was horrified that more than a hundred thousand innocent civilians were instantly incinerated. But no. Like most of the population we were aware of the dreadful atrocities that had been committed by the militaristic regime. Even before the infamous attack on Pearl Harbor.

The decision to drop the bomb, notwithstanding that Japan was already close to defeat, saved more lives than it took. Japanese as well as Allied.
S Parker-Ross, United Kingdom

I was serving aboard HMS Victorious with the British Pacific Fleet. Our planes were on regular bombing missions over Japan.

I can well remember the message that came over the ship's speakers: "An atomic device has been dropped on Japan and therefore the war must be considered to be at an end."

As I recall the message was received in silence. Although there was further enemy activity it did indeed mark the end of the war.
Vic Wainwright, UK

This is the biggest mass murder in the world's history. Everybody who participated in this event must be declared a war criminal. Firstly President Truman.
Josh Akcil, UK

I was born in 1960 - too late to have any direct memory of the bombs dropped on Japan although old enough by the 1970s to realise the horror of what had happened.

In the 1970s I supported the aims of CND and made my views known in no uncertain terms to my parents. It was only recently that my father told me that he had been in training in a parachute regiment to invade Japan when the bombs were dropped.

I feel great pity for the innocent victims in Japan but I doubt I would be here, along with so many others of my age, if this had not happened. This really was a dreadful episode but events cannot be judged fairly by looking only at the civilian consequences in Japan.
Gill, UK

I have always thought that Nagasaki was the true atrocity. One can defend Hiroshima as a military action, in the same way as the bombing of Dresden: the consequences were worse than predicted, but the objective was to hasten the end of the war.

But the Nagasaki bomb was dropped on a country already awed by Hiroshima, ready to surrender, primarily as a technical exercise to find out if the "Fatman" type bomb would work in practice. Nagasaki is less well known, less high profile, but in my view the greater example of inhumanity.

Interestingly, the British observer at Nagasaki was Group Captain Leonard Cheshire, VC - the youngest Group Captain in Bomber Command, CO of 617 "Dambusters" squadron. After Nagasaki he left the service and devoted the rest of his life to caring for the disabled and terminally ill.
Guy Chapman, UK

Let's not rush to point fingers at anyone about the dropping of The Bomb. Practically the entire planet was gripped by war at that time, and when the military is in control, the appreciation of humanity flies out the window.

We are all responsible as human beings for the welfare of all others.

As long as there is only a small percentage of humanity speaking out against militarism or taking direct action in our daily lives to increase the value of humanity, we will always have acts of barbarism. Whether it be on a personal or global level.

Let's take the 60th Anniversary of Hiroshima as another call to renew our efforts to end violence against all people!
Darrell Standring, USA

Mr Pool (below), I salute you, sir. My father was a China Marine, his buddies ended up on the Bataan Death March. He managed to get out, became a Paramarine and participated in the raid on Choiseul and Bouganville, then on to more South Pacific action. He was then deployed to Japan.

I feel this new generation is hasty, they simply do not remember, or have living relatives to remind them of the atrocities which needed to be ended.

It's easy to say Japan was ready to surrender, but I doubt they were. It's easy to say dropping the bomb was a mistake, which I do not believe it was.

The war had to end. Our troops, although ready for an invasion of Japan, were feeling the strain, both in the Pacific and in Europe. I invite these youngsters, so idealistic and sure of themselves to spend some time reading the memoirs of our Fathers.

Look at the faces of our young men, dying by the thousands in the jungles, at sea and in Europe, fighting the first great fight against Fascism.

When I hold my Father's medals, or visit him where he rests at Fort Rosecrans, and see row after row after row of white crosses, I weep for this greatest generation, who sacrificed everything, without a second thought, to give us freedom.

I need to say that the bomb was horrible, it was, but war is horrible, tyrants and their brutal deeds are horrible. Truly what needed to have happened after the end of WWII was a complete nuclear ban.

The bomb served its purpose, and saved more lives than it took, but now, I think most of us would agree that it has brought us dangerously close to the precipice of the end.
Marjorie (Drake) Grisak, Mexico

I'm five years too young to have been around in 1945. However, I discovered an indirect link to the events in Hiroshima through my family history.

My great (x4) grand-father, Edward Burchett, lived in my home town of Hounslow. His son James emigrated to Australia in the 1850s, and James' descendant was Wilfred Burchett, who became a war correspondent and was the first Westerner to report on the devastating effects of the atomic bomb in Hiroshima.

His article appeared in the Daily Express on 5 September 1945, as a "warning to the world".

Wilfred was always a "romantic socialist" - way to the left of my Lib-Dem views - but he never joined the Communists. On the other hand, he became anti-American thanks to his treatment and subsequently reported both the Korean War and the Vietnam War "from the other side".
Stephen Bacon, England