Timeline: the countdown to the atomic bombing of Hiroshima

Since its capture in July 1944, Tinian Island in the western Pacific has been transformed into the biggest air base in the world. But the base also has a secret. In a remote corner, protected by several machine-gun emplacements, a dull-grey, oversized trash can is slowly wheeled from a hangar towards a waiting B-29 bomber. With infinite care, the trash can is winched into the bomb bay. It is a tight fit. Several guards stand by, their weapons ready. Security has never been tighter on this island. The trash can is too valuable. The product of three years research and $2 billion, it is America’s most secret weapon. In less than 12 hours, the bomb they call 'Little Boy' will be on its way to the doomed city of Hiroshima in Japan.

9 hours, 15 minutes

6 August, 00:01. Briefing room, Tinian.

The man standing on the platform fixes his gaze on the men who will fly with him in a few hours. His name is Colonel Paul Warfield Tibbets, a tough, bullnecked 30-year-old with thick black eyebrows and a pugnacious chin. A veteran of the fierce air battles over Germany, he was handpicked 11 months ago to train this squadron and lead this mission. None of his men have been told the exact purpose of that training. They know only that their mission is expected to end the war. And tonight is the night they have all been waiting for.

A chill went over me. The make-believe was over

In the next few hours, declares Tibbets, one of three cities will be hit with a revolutionary weapon, whose destructive power is equivalent to a 2,000-bomber raid. He outlines the targets in order of priority: Hiroshima, Kokura, Nagasaki. Three B-29s will fly to these cities one hour ahead of the strike force to check the weather. The city with the best conditions will be selected for attack. Special tinted goggles are then handed out. Tibbets tells everybody to wear them over the target, otherwise they could be blinded. This bomb was going to be brighter than a super-sized sun. The tension in the room is electric. “A chill went through me,” writes Abe Spitzer, a radio man, in his diary. “The make-believe was over.”

Meanwhile, 9,000 miles away, on board the USS Augusta in the mid-Atlantic, US President Truman emerges from Sunday service. He is half way home from Potsdam. Yesterday, he received word that the atomic mission was set to depart at 02:45 Tinian time.

His decision to use the bomb is not made without misgivings, but President Truman sees no real alternative. Just a few weeks previously, his joint chiefs of staff had presented their timetable for the projected invasion of Japan. The invasion is planned in two phases. The first, Operation Olympic, is scheduled for 1 November; the second for March 1946. Estimates of casualties vary, but one thing is certain: the Japanese will fight to the bitter end. Still fresh is the memory of Okinawa, the island south of Japan, captured in June after three months of brutal fighting. At least 12,000 Americans and 107,000 Japanese soldiers were killed.

To the president, the one solution to the even greater carnage of an invasion of the Japanese home islands is now hanging inside a B-29 bomb bay on the other side of the world.

6 hours, 49 minutes

02.27. Tinian.

Before departure, the air crews are subjected to a battery of photographers. By tomorrow the news will be splashed across the world. The B-29 dazzles under floodlights like some Hollywood premiere. Finally the men climb aboard. A photographer snaps a last photo. Tibbets waves out of the window. Beneath him is the name of his plane, Enola Gay. It is also the name of his mother, immortalised in ways neither of them could possibly imagine.

The runway is one and a half miles long. Fire trucks are parked along its edge. With its big bomb, Enola Gay is dangerously overloaded. In the past 24 hours, four B-29s carrying conventional bombs have crashed on take-off. If Enola Gay also crashes, it could set off a nuclear accident, wiping out the entire island. As he opens the throttles, Tibbets notices his hands are sweating. The plane races down the runway. Just before it runs into the sea, Tibbets hauls the wheels off the ground. A minute later, two other B-29s follow, one packed with cameras, the other with observers. All three aircraft disappear to the north, for the start of their 1,500-mile flight to Japan. But nobody yet knows on which of the three cities the bomb will drop. The lives of thousands of now-sleeping people depends on what the weather will be like tomorrow morning.

6 hours, 26 minutes

02.50. Hiroshima.

Despite the blackout, Hiroshima is still relatively comfortable in this fifth year of the war. Even a few cinemas are still open. Earlier tonight, people streamed to the Kotobuki Theatre to see one of the season’s hit movies, Four Weddings. But food is scarce. A staple diet for the city’s 330,000 inhabitants is grass. The one consolation is that Hiroshima has so far escaped the bombing. Over the past few months teams of schoolchildren have pulled down houses to create firebreaks in case the bombers come. But they never do.

A week ago, the mayor brought his baby granddaughter to stay because, he wrote, Hiroshima “is so safe”. A rumour is spreading that Truman’s own mother is a prisoner in the city – that is why it has never been, nor will be, bombed. The order to spare it has come from the president of the United States himself.

6 hours, 16 minutes

03.00. Enola Gay.

Within minutes of take-off, a balding naval captain on board Enola Gay opens a hatch at the rear of the flight deck and steps down into the dark bomb bay. His name is Deak Parsons and his job is one of the most dangerous of this mission. In the next few minutes he will arm the atomic bomb. With an assistant carrying a torch, he squeezes past Little Boy’s black bulk. Only the thin bomb-bay doors separate him from 5,000 feet of thin air. Squatting to work with a set of tools. Over the radio he relays each stage of the arming operation back to Tinian. There are 13 stages. Despite the vibration and the turbulence, his concentration is total. It has to be. A slight slip and the mission could end in disaster. Back on Tinian, General Farrell listens to the radio. By the time Parsons reaches stage eight – Connect Firing Line – his voice disappears into static. At this point, nobody on the ground is certain whether Parsons has succeeded, or blown himself and Enola Gay out of the sky.

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4 hours, 16 minutes

05.00. Tokyo.

Within the sanctuary of his palace, Emperor Hirohito, Son of Heaven, watches the dawn after another sleepless night. These days, he does not look much like a god. Most of the time he wanders aimlessly through his palace in old clothes and slippers. His right cheek twitches uncontrollably. He knows the war is lost. Despite the army fanatics on his council, he is desperate to find a solution. All his hopes lie with the Russians, still at peace with Japan. Perhaps they will broker a deal with the Allies. His ambassador in Moscow, Naotake Sato, has opened negotiations but so far they have met with failure. Sato is a realist. In his mind, there is only one way to end the war: unconditional surrender. “If the government and military dilly-dally,” he cables Tokyo, “then all Japan will be reduced to ashes”. It is a typically prescient remark, more accurate than Sato could ever have imagined.

1 hour, 7 minutes

08.09. On board Straight Flush, 30,000 feet over Hiroshima.

The moment he approaches Hiroshima, Buck Eatherly knows it will be today’s target. As captain of the weather plane assigned to the city, conditions look near-perfect. A huge hole has miraculously opened in the clouds, exposing its heart. Twice Eatherly sweeps over it – both times completely undisturbed – before his radio man sends the weather report back to the strike force, one hour behind. On board Enola Gay, Tibbets receives the message. “It’s Hiroshima,” he says. He adjusts his course towards the city. Co-pilot Bob Lewis jots a note in a private log: “Well folks, it won’t be long now”.

45 minutes

08.31. Hiroshima.

Despite an alert, hardly anyone takes notice of Eatherly’s plane. After all, the Americans never drop bombs. Trams trundle over the city’s 49 bridges, packed with commuters.

Some of the resident 43,000 soldiers perform their morning calisthenics in the sunshine. Schoolchildren stream to their places of work in factories and offices, for there is no school these days. Everybody is mobilised for the coming invasion. Even the nurses in Hiroshima’s hospitals practise thrusting bamboo spears against dummy enemies. Meanwhile, the city’s newspapers scream out the same bullish headlines. “The Fighting Spirit of the People Lives on,” reads one, adding that victory is just around the corner.

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5 minutes

09.11. Aboard Enola Gay, 22 miles from the Aiming Point.

To Major Tom Ferebee, the bombardier, the city glinting on the horizon is instantly recognisable from countless photos. The only difference is that it is in colour. A handsome Errol Flynn look-alike, Ferebee is a master of his craft, a veteran of 63 missions. Tibbets once described him as “the best bombardier in the whole damn air force”. His eyesight is legendary. He is not the sort of man to miss.

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With his left eye pressed to the bombsight, he searches the dense grid of streets for one feature. Then he sees it: a bridge where the Ota river branches in two, shaped like a T – the aiming-point for the bomb. His voice bursts over the intercom: “I’ve got the bridge”. Tibbets immediately warns everyone to put on their goggles. At 09:15 Ferebee flicks a switch. A warning tone howls over the airwaves. In exactly 15 seconds, Little Boy will drop into the clear blue skies over Hiroshima. “There will be a short intermission,” Lewis notes in his log, “while we bomb the target”.

3 minutes

09.13. Air defence bunker, Hiroshima.

In Saijo, east of Hiroshima, an observer spots all three aircraft heading towards the city. He calls the air defence bunker. A schoolgirl takes the message: “Three large enemy planes heading west. Top alert”. In a radio station 1,000 metres from the T-shaped bridge, an announcer is finishing breakfast when the bell in the alert room starts clanging. Masanobu Furuta’s job is to broadcast air raid warnings to the citizens. Now he rushes to the studio as an engineer thrusts the latest warning into his hands.

44 seconds

09.15.17. Aboard Enola Gay.

The warning tone cuts. The single shackle drops its dead weight into the freezing air. It wobbles before plunging towards the city. Tibbets immediately slams the big bomber into a tight diving turn. He has exactly 44 seconds to escape before the bomb explodes. As Enola Gay tears away, Little Boy continues its fall, accelerating almost to the speed of sound. From the observation aircraft, blast gauge canisters float down over the city, suspended from parachutes. Some of the inhabitants cheer. They think one of the bombers has just been shot down. In the radio studio, Furuta begins speaking into the microphone: “Three large enemy planes approaching…” He gets no further. The station suddenly tilts as he is hurled into the air. Before the sirens have a chance to sound, the sky falls in over Hiroshima.

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Zero hour

09.16.01. Hiroshima.

The impact on the city is immediate and catastrophic. In the first billionth of a second the temperature at the burst-point reaches 60 million degrees centigrade, 10,000 times hotter than the sun’s surface. A blinding flash lights up the sky. Within the first three seconds, thousands of people are incinerated, carbonised into charred smoking bundles. Birds ignite in mid-air. Steel-framed buildings liquefy like wax.

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Hard behind comes the shock wave, ripping out at the speed of sound, crushing every obstacle that lies in its path. The wall of high pressure leaves a near vacuum behind, sucking viscera out of bodies. Hundreds of radioactive isotopes spill out of the fireball, penetrating flesh and bone. Within 500 metres the effect is invariably lethal. American scientists later call this zone the “scare radius”. Perhaps 80,000 people die in those first seconds after the blast. Thousands more will die later from burns or radiation poisoning, among them the mayor and the baby granddaughter he brought to the city because it was so safe.

Nine miles away, the shock wave strikes Enola Gay with a tremendous crash. “My God,” thinks Dutch Van Kirk, the navigator, “the bastards are shooting at us!” Tibbets fights to keep the plane under control. In the tail, rear-gunner Bob Caron watches in astonishment as the biggest cloud he has ever seen punches up into the sky. Beneath it Hiroshima has disappeared. Grabbing a camera, he takes seven photos of the mushroom-shaped cloud: iconic images of Hiroshima’s annihilation. The cloud surges into the stratosphere. Lewis stares in shock. “My God, what have we done?” he writes in his log. “If I live for a hundred years, I will never get these few minutes out of my mind.”

Was the US justified in dropping atomic bombs on Hiroshima and Nagasaki during the Second World War? We put the question to historians and two HistoryExtra readers. Share your views by commenting below, tweeting us @HistoryExtra or by posting on our Facebook page.

This article was first published in the August 2005 issue of BBC History Magazine