The men crouched inside the cave, their faces streaked with dust, occasionally flinching involuntarily at the explosions overhead, which seemed to shake the entire mountain.

Outside was a vision of hell.

Vast plumes of smoke and debris were thrown up into the air as US B-52 bombers and fighter jets let loose a seemingly endless barrage of missiles. The noise from the bombardment could be heard from miles away, a deep, hollow booming sound as each bomb struck.

It was December 2001, and the target of the strikes was Osama bin Laden, orchestrator of the attacks on New York and Washington three months earlier. He was believed to be hiding out, along with a core of al Qaeda fighters, in Tora Bora, a cave complex south of the city of Jalalabad, in the mountains between Afghanistan and Pakistan.

Whether Bin Laden was there at all remains disputed, but if he was, he managed to slip away, along with several other top al Qaeda leaders, avoiding both the aerial bombardment and US and Afghan troops on the ground. He would dodge US forces for another decade, before being tracked to a suburb of the Pakistani city of Abbottabad, where he was killed in 2011.