Maj-Gen Charles Sweeney

The first bomb ever dropped by the US Air Force pilot Charles Sweeney was also one of history's most portentous: the five-ton plutonium bomb that devastated the Japanese city of Nagasaki in 1945. Three days after Hiroshima, it confirmed the arrival of the nuclear age and pushed a petrified Japan to unconditional surrender, thus ending the Second World War.

Charles William Sweeney, pilot: born Lowell, Massachusetts 1919; married (three sons, seven daughters); died Boston, Massachusetts 16 July 2004.

The first bomb ever dropped by the US Air Force pilot Charles Sweeney was also one of history's most portentous: the five-ton plutonium bomb that devastated the Japanese city of Nagasaki in 1945. Three days after Hiroshima, it confirmed the arrival of the nuclear age and pushed a petrified Japan to unconditional surrender, thus ending the Second World War.

Sweeney, then 25, was in fact the only pilot to witness both atomic detonations over Japan. On 6 August he flew a weather-instrument plane behind the Enola Gay, the B-29 that dropped the bomb on Hiroshima. On 9 August, he was at the controls of the Bock's Car, which struggled with inclement weather and significant mechanical problems before finding its target.

Throughout his subsequent life, as he was promoted to major-general and then pursued a second career as a shoe-leather salesman in his native Massachusetts, Sweeney never ceased to defend his actions. He dismissed critics who questioned the morality and the strategic necessity of the Nagasaki bomb as "cuckoo professors" and "cockamamie" theorists who did not understand the far greater loss of life that a full-scale ground invasion of Japan might have entailed.

"My only consideration was to stop the goddam war and get our guys home," he said in a 1995 interview:

Truman was absolutely right. He would have been derelict in his duty if he hadn't used it [the bomb].

When a 50th anniversary exhibition at the Smithsonian Museums in Washington promised to question the necessity and motivation for the Nagasaki bomb, Sweeney responded by writing a memoir entitled War's End: an eyewitness account of America's last atomic mission (1997), in which he described the eerie and often nerve-racking progress of his most famous mission.

The Bock's Car developed a fuel problem early on in its flight, then failed to find a break in the clouds above Kokura, the original target city. Nagasaki was also shrouded in cloud and smoke, but with his fuel gauge running ever lower Sweeney found the clearing he was looking for, dropped his load, nicknamed "Fat Man" because of its bulging form, and swerved away just in time.

"Suddenly the entire horizon burst into a super-brilliant white with an intense flash - more intense than Hiroshima. The light was blinding," he wrote:

I could see a brownish horizontal cloud enveloping the city below. From the center of the brownish bile sprung a vertical column, boiling and bubbling up in those rainbow hues - purples, oranges, reds - colors whose brilliance I had seen only once before and would never see again.

One of his crew members described the force from the blast making the plane feel as though it was being "beaten with a telephone pole". On the ground, as many as 87,000 people were killed and roughly 30 per cent of the port city levelled.

Sweeney had hoped to fly back to base on Tinian Island, but the fuel problem forced him to make an emergency landing on Okinawa. As first one and then a second engine failed on the way down, he landed with just seconds to spare.

Sweeney received multiple decorations for his performance that day, and later became the youngest brigadier-general in US Air Force history.

Andrew Gumbel