One of only 2 times that nuclear weaponry has been used in combat, the drop on Hiroshima started the clock ticking so to speak on the inevitable Japanese surrender. Looking back, it is incredible to me that they had not already surrendered considering that Germany (their only remaining ally) had surrendered several months ago and now all Allies were focused on Japan where previously it had been limited to mostly the United States.
The bomb was nicknamed "Little Boy" and it's counterpart, which was actually a very different type of bomb, was named "Fat Man." Little Boy was carried on the B-29 Bomber the Enola Gay, which was named after the pilot (Colonel Paul Tibbets)'s mother and was accompanies by two other B-29 aircraft. Only Tibbets and two of his crew had any idea that Little Boy was actually a new type of weapon with devastating capabilities. The other crew on all planes were just given dark goggles and instructed to use them: They were not told why.
Prior to the bombing run, US military command had contemplating doing a "free trial" on an uninhabited island to demonstrate to the Japanese what was headed their way but in the end it was determined that the top brass wasn't even sure if the bomb was actually going to work, and to have a demonstration fail would be too embarrassing (these are my words, the official report is considerably more cordial.)
While they did not give any specifics, more than 60 million leaflets were airdropped into Japan warning civilians about certain areas being prime targets for upcoming bombing runs. I know the point of this propaganda was to demoralize the enemy and change the Japanese attitude towards the war.... well, it must have been... because where were these people supposed to go to hide? It's not like Japan is an enormous country with tons of countryside.
The warnings had no effect on the Japanese war machine nor the overall sentiment of loyalty to the state. Well, at least they tried.
The bomb detonated about 600 meters off the ground, as it was intended. The destruction was immediate and the radius of complete destruction was around 1 mile. This is where all sentient life and most structures were immediately vaporized. 30% of the city's population was immediately killed by the blast and "firestorm" that followed. As I am sure you are aware, the aftermath saw many consequences such as radiation poisoning and other such horrible ends that I think is far worse than just being vaporized.
As devastating as that sounds, the bomb was actually considered to be "very inefficient" as less than 2% of the uranium actually did what it was supposed to. I would imagine they have perfected that chemical reaction by now so this was probably not an accurate representation of what today's bombs could do.
Despite being made of reinforced concrete to protect against earthquakes, very little in the way of structures remained near the epicenter of the blast. The most famous "survivor" is the above building, which has since been renamed the "Hiroshima Peace Memorial" which is an odd and ironic name for a building that withstood the most devastating military blast of all time.
Personally, i want to know what kind of trees those are in the picture. I might have finally found a plant that a might be able to accommodate in my completely inept gardening.
It is difficult to imagine, but even after facing such utter devastation, the Japanese decided to fight on despite this and the fact that the Soviet Union was also now advancing from the north. They were truly a determined people the Japanese but even this fervor would be squashed just a few days later.