On this day 70 years ago, the world and the preconditions for its health and survival changed forever. A crude bomb containing 60 kilograms of highly enriched uranium exploded 580 metres above Hiroshima. Equivalent to 15,000 tons of TNT, it was 2000 times more powerful than the British Grand Slam bomb, the largest produced until then.
The moral threshold of catastrophic attacks with indiscriminate weapons had already been crossed, with poison gas killing 90,000 and maiming or blinding one million men in the European killing fields of the first world war. This was followed by indiscriminate aerial bombing of cities during the second world war.