În dimineața zilei de 6 august 1945 locuitorii orașului Hiroshima au putut vedea și auzi pe cer o formație de trei avioane de bombardament americane B-29 Superfortress aparținând forțelor aeriene ale Statelor Unite ale Americii survolând orașul. Fiind o formație mică de avioane de bombardament, comandamentul apărării anti-aeriene japoneze a decis să nu intercepteze avioanele americane, bănuind că este vorba de o nouă misiune de recunoaștere lansată SUA în vedere unei serii de bombardamente împotriva centrelor industriale și urbane japoneze.
Few events have had such a deep impact on world history as the conflict that griped the international system seventy years ago. As all great power wars in the last five hundred years it started in Europe, with a bid a for hegemony made by a Germany, the second in twenty-five years, but it soon spread to North Africa, the Pacific and the Atlantic oceans. World War II was a total war, the second in less than a generation, and as such it involved attacks on civilians and genocide. From a military and strategic point of view it was a total war, as the aim of the war was the re-ordering of the entire international system and the destruction of some of its members; its scope was not limited to the European continent, it saw an unprecedented level of societal mobilization for the war effort in every country involved and it was prosecuted with every means available, culminating in the atomic bombings of Hiroshima and Nagasaki.