Late on May 1st 2011, rumours began to spread across Washington that President Obama was planning a late-night address to the American people.
The speech was clearly going to mark an exceptional event. It was a Sunday; it was late at night. There was no precedent for such a strangely-timed appearance. Perhaps most remarkably, Washington - which leaks like a sieve - had kept a secret. Very few people had any idea what the President would say that night.
We didn't have to wait for long. Seal Team Six would enter American military folklore. Abbottabad would soon be known as Bin Laden's final lair. President Obama would have the greatest triumph of his first term.
But a year on, one of the great riddles remains the character of the man who ordered the audacious, high-risk commando raid.
President Barack Obama won a Nobel Peace Prize almost as soon as he entered the White House. He was widely seen as the anti-Bush; as a political leader who would seek to limit America's military engagements.
Now look at the last three years. He has made drone warfare his signature operation. As one analyst has calculated: President Bush ordered a drone strike in Pakistan every 43 days; Obama approved one every four days.
Furthermore, the Obama White House has approved the deployment of US forces in six Muslim nations: Libya, Yemen, Somalia, Pakistan, Iraq and Afghanistan.
No-one expected President Obama to become so enthusiastic a proponent of Special Forces, covert operations and selective assassinations. He even gave the green light to the extra-judicial killing of an American citizen, Anwar al-Awlaki.
It raises the question of where a second-term Obama Administration would go. Will his love affair with Special Ops continue? Will it end not in triumph but in a debacle?
As you might expect, the Republicans are complaining that the President is cynically exploiting the bravery and skill of American troops for his own re-election campaign.
Certainly the White House is claiming full credit for the death of Bin Laden. That famous photo of the President and his advisers in the Situation Room is integrated into a hundred campaign ads.
Is this a justifiable case of high-risk, high-reward for the President? Democrats say that Obama made the tough call and that he deserves to reap the political reward.
Or are the Republicans right to say that Mr Obama should give the full credit to those who risked their lives a year ago during that moonless night in Abbottabad?