It's 70 years since Allied forces dropped the world's first atomic bomb on the town of Hiroshima in Japan, on a day that promised to bring an end to World War II, and changed the course of history.
I have visited Hiroshima, and can testify to the will of its citizens who found the spirit, resources and energy to rebuild their city into one as vibrant, energetic and purposeful as any in Japan. Set apart from the bustling temples of commerce and enterprise, one small, domed building stands alone - an old exhibition hall, it was the only central structure to survive the bombing and now serves as the peace memorial, and tribute to the 70,000 people killed instantly, and the further 70,000 who suffered the fatal effects of radiation.
The bomb 'Little Boy' destroyed five square miles of the Japanese city
For some, though, it could have happened yesterday, and ITV last night broadcast a moving minute-by-minute account of that day, 6 August 1945. In a word that has been horribly stolen, the archive footage was truly awesome both in the precision of the military campaign, the scale of the blast, and the brutal efficiency of its effect.
The programme had all the necessary context - the race by the Allies to create a bomb before their Nazi enemies, the effect of the bomb on the Japanese surrender, the science behind the Manhattan Project.
The documentary brought us personal accounts from both sides of the conflict
However, it was the survivors on both sides, their calm and matter-of-fact tone belying the trauma, who really gripped with their incredibly personal accounts of how their lives had been defined by this one, overwhelming event.
One of these, Yoshie Oka, remembered seeing a soldier burnt on the ground, who said, "We've been hit by a new type of bomb."
Most moving of all, the documentary was balanced by the memories of US airman, Dutch Van Kirk, the navigator of the flight crew of the Enola Gay plane which dropped the bomb.
This was his last interview before he died, and he'd had many years to try to make sense of the events of 1945, but his practical, almost casual account of his role defined all too well the moral dilemma at the root of weaponry that continues to this day, and makes this essential viewing for anyone determined that this kind of enormous tragedy is consigned to history where it belongs.