Early in the morning of 6 August 1945 the B-29 Enola Gay of the 509th Composite Group piloted by Col. Paul Tibbets took off from Tinian for a bombing mission over Japan. At 0815 on that Monday morning the bombardier released one bomb over Hiroshima.
Forty-three seconds after release the 9,700 lb. uranium bomb ‘Little Boy’ detonated 1,900 feet over the city, instantly vaporizing everything within a half-mile of the hypocenter and flattening everything else out to nearly a mile from the center of the explosion. An estimated 70, 000 people died instantly; the total death toll from secondary effects is estimated at upwards of 200,000.
The estimated yield from the bomb was 15 Kt, or about 15,000 tons of TNT. The average yield of a nuclear weapon in the U.S. arsenal today is about 250 Kt. At the height of the Cold War bombs in the megaton (Mt) range were common and the largest weapon ever detonated was the Soviet ‘Tsar Bomba’ with an estimated yield of 50 Mt.
I once took a course that dealt with the events and rationale leading to the nuclear bombing of Japan and the political effects of that decision. The public version of events is that the bombings were necessary to bring a swift conclusion to the war (Germany had already surrendered) and prevent casualties estimated between 500,000 and 1,000,000 on the American side and millions more on the Japanese side that would result from an invasion of the Home Islands.
The fact is that by August 1945 the Japanese Navy and Air Force had essentially ceased to exist as effective fighting forces. Four years of unrestricted submarine warfare against the Japanese merchant fleet had visited serious economic hardship on the island nation along with an estimated 600,000 civilian casualties from bombing raids. It’s not at all clear that the Japanese civilian population would have fought as tenaciously as predicted given their tribulations.
One of the possible reasons given in that class for nuking Japan was that Truman was sending a message to the Soviets: These are the effects of these weapons. This is what we will do. Don’t mess with us.
There is a reasonable argument to be made that the 250,000 Japanese who died from nuclear bombs in August 1945 secured the future of hundreds of millions of people in the ensuing 50 years of the Cold War. In the horrible calculus of the nuclear age this is considered reasonable. Those who lived through the Bad Old Days with the very real threat of nuclear war hanging over their heads might find some of the current societal preoccupations bemusing if not actually ridiculous. We’ve lived through worse.
Thus far the United States is the first and only nation to use nuclear weapons on another people. May it ever remain so.