For seven long years, hundreds of U.S. airmen flew sortie after sortie against North Vietnam's formidable and strategically important Thanh Hoa ("Dragon's Jaw") bridge, dodging a heavy concentration of anti-aircraft fire and enemy MiG planes. Many American airmen were shot down here, and if captured, taken to the infamous "Hanoi Hilton" POW camp. But after each air attack, when the smoke cleared and the debris settled, the bridge stubbornly remained standing. For the North Vietnamese it became a symbol of their invincibility, and as this history details, for American planners and soldiers, it became an obsession.