How Obama kept the biggest secret of his presidency

Even the most diligent felt happy switching off after lunch on Sunday. The President had cut short a golfing trip to Maryland (rain was threatening) and returned to his family early. A reporter accompanying him told colleagues in an email that the "lid" was coming down – the moment in the day when nothing more Obama-related was expected. "Arrived at White House after uneventful trip at 2:04," she typed. "Enjoy the rest of the weekend!"

No politician can reach such high office without being good at cheating on the American public, particularly where national security is concerned. Every commander-in-chief will have a moment when that capacity to keep a secret – and maintain a poker face – is tested to an almost unbearable degree. For Barack Obama it came over three days on the cusp of April and May in 2011.

For those 72 hours, the public part of the President's schedule was followed with the usual alacrity by the White House press corps. It was at 8.43am on Friday that Obama boarded a helicopter on the South Lawn (khakis and dark jacket) with his wife Michelle and their two daughters on the first leg of a trip to Alabama to console tornado victims, and thereafter Cape Canaveral in Florida to visit Nasa.

As they toured a shuttle hangar – "Think about that, eight minutes and you're up in space," Obama told his girls – Vice President Joe Biden headed to the British Embassy in Washington for a party to celebrate the royal wedding. He was on characteristically garrulous form, reminiscing about a trip to Britain with his late mother. It would have been hard to stop him talking.

Fast-forward 24 hours to the Washington Hilton and Obama was taking the art of nonchalance to a higher plane. For 20 minutes, in front of journalists and Hollywood stars at the White House Correspondents' dinner, he played the joker, alternately making a chump of himself and of Donald Trump. Who could have guessed at his anxiety about an imminent Special Forces operation in Pakistan that was set either to make his presidency – and his chances for re-election – or sour it horribly?

While the clock on the effort to take out Osama bin Laden had actually begun ticking late last summer, when CIA analysts first identified a high-walled compound in a town north of Islamabad that looked to be the lair of the al-Qa'ida leader, the final countdown had really started at 8.20am on Friday, barely 20 minutes before the Obama family boarded that helicopter on the South Lawn.

In the Diplomatic Room of the White House, the President sat across from four of his top aides, including the National Security Advisor, Tom Donilon. All were part of a very tight circle that had been deliberating with him about when and how the proposed assault on the compound should unfold. The option to drop a crushing payload of bombs on it had been ruled out by the President, who wanted Bin Laden, or his body, to be recognisable when it was all over. A boots-on-the-ground raid by Navy Seals was what he favoured. But were the plans fool-proof, and were they certain Bin Laden would be there?

The aides came to the meeting prepared to brief Obama. Saturday looked tricky weather-wise, but he cut them off before they started. "It's a go," he told them, and that was that. John Brennan, the top anti-terrorism advisor, would later describe it as the "gutsiest" decision made by a US president in recent memory.

As had been advised, the conditions meant that Sunday – or the very early hours of Monday in Pakistan – would bring the moment when America would, after more than a decade of frustration, finally have its best shot at eliminating its Enemy Number One. Obama and his co-conspirators, who included Robert Gates, the Defence Secretary, and Hillary Clinton, the Secretary of State, would have to hold their tongues a little while longer.

Possibly it was helpful that there was plenty else going on in the world as a distraction. Biden had played his part, pretending that the only thing that mattered over this long weekend was a certain ceremony far away in Westminster Abbey. And Obama went through the rituals of the Correspondents' Dinner that most presidents find excruciating under any circumstances. In fact, he received high marks for his comedy.

But there were clues that something was up. Anyone watching closely on Sunday might have wondered at Obama stopping after nine holes of golf when he usually plays 18. The moment he got back to the White House – and that "lid" was declared – he raced to the Oval Office in his golfing shoes, rather than to the family quarters to change. Meanwhile, all tours of the West Wing – Hollywood types from the previous night's dinner were expected as well as tourists – were cancelled. No one wanted Scarlett Johansson or Sean Penn bumping into a furrow-browed Robert Gates.

It was on Sunday afternoon that the drama of at last netting "Geronimo" – the codename given to Bin Laden for the operation – began. Obama, Clinton, Gates, Donilon, Brennan and a few others huddled in the White House Situation Room. A video and audio link connected them to Leon Panetta, the CIA director in Langley, Virginia, who would talk them through what was going on in Pakistan in real time, beginning with the helicopters carrying the Seals clattering through the night sky and arriving above their target. It was just after 2pm.

According to Brennan, the atmosphere in the room was intolerably tense. Between bulletins from Panetta, those inside said almost nothing. "They've reached the target," Panetta began, according to one version reported by the New York Times. Minutes later, he added: "We have a visual on Geronimo." Finally, they heard Panetta say: "Geronimo EKIA [enemy killed in action]." Still nobody said anything, as if to do so would jinx this victorious moment. Then Obama looked up and said simply, "We got him."

There was still some work to do. A photograph of the dead Bin Laden was uploaded by a commando on site to help experts at Langley confirm his identity. Later, a DNA analysis offered a 99.9 per cent match. As the body was taken into Afghanistan and the Navy prepared to dispose of it at sea, Obama began making calls to those who had to be let into the loop first, among them his predecessor, George W Bush.

Eventually, it was time to tell the rest of the world. The "lid" was rescinded and all White House correspondents were summoned back to their stations. And no one knew why until just a few minutes before Obama finally came into the East Room to speak at 11.35pm.

We like to think that every secret is leaked eventually. The tracking down and killing of Bin Laden was the best Washington secret in years. And, as it happens, it was clearly one of the best kept ones, too.