The city of Hiroshima, Japan was ordered to be built on the shores of Hiroshima Bay on April 15, 1589, by a Terumoto Mori from Koriyama Castle of Yoshida, Takata County. The city was finished, with a castle and a moat, in 1593. The islands of Niho, Eba, and Ujina (present Motoujina) were merely small islands at that time, but gradually grew larger as silt collected with time; these became part of the growing Hiroshima area. Hiroshima gained a commercial port in 1880, and then a railway in June of 1894, and both were used to transport military goods. Hiroshima then became a military district, with the wonderful port location and easy transportation access, it was quite suitable for a military installation. Many military installations were built when it was decided to convert Hiroshima, one after the other, steadily strengthening Hiroshima as an army base.

Through a barrage of wars, Hiroshima prospered and became an economic and educational city, as well as a military city. Japan entered the Greater East Asia War (the Pacific War) when they launched an attack on the northern Malay Peninsula and attacked Pearl Harbor in Hawaii on December 8, 1941. Japan was divided into two parts during the war, as the Japanese wanted to be prepared in case Tokyo fell. The First General Headquarters was situated in Tokyo, with the Second General Headquarters, under the command of Marshal Shunroku Hata, in Hiroshima, where the headquarters of the Chugoku District Governor-General (led by Isei Otsuka), the highest administrative body commissioned by the central government, was also established.

The very real fear of air raids and bombings prompted evacuations of non-essential people from Hiroshima, and middle school girls helped clear fire lanes, just in case of a bombing, to control the spread of fire.

On August 6, 1945, the United States of America dropped the atom bomb on Hiroshima, Japan. This bomb instantaneously destroyed almost every building in Hiroshima with the power of nuclear energy, in the form of fission. Wooden houses crumbled or caught fire and burned to ashes, while concrete buildings' roofs fell in or collapsed. Many city officials died in the explosion, with a total of more than 100,000 dead, including Mayor Awaya, who died at his home. The number of dead also includes the people who died of radiation sickness in the following years.

The dropping of the atom bomb on Hiroshima and Nagasaki ended World War II, but then the Cold War began.