Shattered 'invisibility': 9/11 inspired a generation to enlist

The 19 hijackers who crashed planes into the World Trade Center in New York City, the Pentagon, and a field in Shanksville, Pennsylvania, loom large in the minds of men and women who have enlisted in the military over the years.

Twenty years ago, on Sept. 11, 2001, in attacks orchestrated by al Qaeda leader Osama bin Laden, nearly 3,000 people lost their lives. What followed was a vow by then-President George W. Bush to enact revenge on the terrorists responsible and two decades of war in Afghanistan and Iraq.