Hunkered down in a mountain-top ravine, armed only with a pistol, and with gun-toting tribesmen bearing down on him, the US Airforce colonel probably had slim hopes for his survival.However, after what is being called the 'most daring' Special Forces rescue operation in US history, he is now safely out of Iran.It took hundreds of Special Forces commandos, a CIA drone operation, and some lateral thinking to avert last-minute disaster.Step-by-step, this is how the rescue operation unfolded.