Three days after a USAAF B-29 named Enola Gay dropped a special weapon over Hiroshima, another B-29 named Bockscar dropped a different type of special weapon over Nagasaki.
We all know that the damage was extensive and devastating, as can be seen in these photos:
The device that caused this damage was small by the standards of the day, but is enormous by today’s standards.
The actual fissile core was approximately 6.4 kg of 239Pu, but the entire weapon weighed in at a little over 4,600kg and was about 3.3m long and 1.5m in diameter and yielded about 21kt. For comparison, a W88 warhead – currently in the US arsenal – is approx 0.5m in diameter, 1.75m long and weighs about 360kg and yields about 475kt.
President Truman issued a communique after the Hiroshima attack that left little doubt of his resolve:
If they do not now accept our terms, they may expect a rain of ruin from the air, the like of which has never been seen on this earth. Behind this air attack will follow sea and land forces in such numbers and power as they have not yet seen and with the fighting skill of which they are already well aware.
Later, in an expression of humility that seems quaint given our current leadership, President Truman had something additional to say:
I realize the tragic significance of the atomic bomb … It is an awful responsibility which has come to us … We thank God that it has come to us, instead of to our enemies; and we pray that He may guide us to use it in His ways and for His purposes.