s.e.a.l.s would rather die than be captured. at the end of the day it was a leap of faith. reporter: friday, april 29, just after 8:20 a.m., the mission begins. the president gives the go. the president, after a long night s sleep, basically came in and immediately told the staff, you ve got the green light. let s go. reporter: as president obama departs for the tornado-ravaged south, the u.s. military s best-kept secret is under way. the troops were ready and in place. the equipment was ready to go. the plan had been practiced again and again and again. reporter: america s most wanted man may finally be in reach. osama bin laden. the architect of 9/11 had eluded the world s most powerful nation for more than a decade. the trail was quite cold. reporter: former cia director michael hayden recalls the early misfires. most of what he had looked more like elvis sightings than intelligence. reporter: the trail caught fire last august when u.s. intelligence