Hiroshima was very involved in the military starting from the mid-19th Century and had a very powerful influence in the government since the 1930s. I know we’re always taught that WWII started in ’41, but that was just the war with the United States. Japan was actually at war with China from around ’37. Why?? Because Japan was in China and Korea trying to seize land, for of course, more power.
At the same time, the Nazi’s were sending Jewish people to concentration camps, while also trying to conquer land in other countries.
During WWII, Germany, Japan, and Italy were an alliance, and basically everyone else was an ally (Please keep in mind that correlation does not mean causation, just trying to put things in perspective in terms of why certain countries took the actions they did)
Around ’39 Britain and France declared war on Germany. Though claiming neutrality, USA still provided resources for the Allies.
Seeing the USA as a threat to their power in the Pacific, Japan bombed Pearl Harbor in ’41 and Germany declared war on the USA directly after. USA began to create atomic bombs because they feared Germany was also doing so. Therefore, initially they were meant for Germany, not Japan.
Germany surrendered in May of 1945, but Japan continued because the military didn’t believe in surrendering (this is closely related to the concept of sepuku, killing one’s self through the stomach with a dagger; Japanese military men would rather kill themselves than surrender, and they did exactly that on many occasions)
US offered the Potsdam Declaration which essentially asked for an unconditional surrender. However, it was extremely vague and Japan wanted to keep their emperor, so Japan didn’t agree to it (the emperor did not have the power at this time, the military did, and the Allies failed to recognize this which was a huge mistake on both parts)
On August 6, the bomb on Hiroshima was dropped. In a city of 350,000 it is said that 140,000 died by the end of the year. This figure does not include people who died to aftereffects, i.e. radiation poisoning. On August 9th, because Japan had not responded to the bomb on Hiroshima, another bomb was dropped on Nagasaki, though less potent due the mountains absorbing the blast. On the 14th, Japan surrendered, officially ending WWII.