Book excerpt: Tuesday, Sep. 11, 2001, dawned cool and clear, with sunny skies all along the eastern seaboard. For Air Force aviators like Lt. Col. Timothy "Duff" Duffy of the 102d Fighter Wing at Otis Air National Guard Base, Massachusetts, the day held the promise of perfect flying weather, at a time when the U.S. civil aviation system was enjoying a period of relative peace, despite concerns about a growing terrorist threat. More than ten years had passed since the last hijacking or bombing of a U.S. air carrier. That morning, however, the country came under a shocking, coordinated aerial assault by nineteen al Qaeda hijackers...The attack plan carried out by the suicide operatives had been years in the making. It was intended to cause mass, indiscriminate casualties and to destroy or damage the nation’s financial, military, and political centers, four high value U.S. targets selected by bin Laden, independent operator Khalid Sheikh Mohammed, and al Qaeda operations chief Mohammed Atef... By the time 1 World Trade Center, North Tower, collapsed at 10:28 a.m. EDT, almost three thousand people had been killed or were dying; the financial center of the U.S. had been reduced to burning, toxic rubble; the iconic symbol of the military strength of the country had been severely damaged; the tranquility of a field in Pennsylvania had been shattered; U.S. Air Force and Air National Guard fighter aircraft had set up combat air patrols over Washington, D.C., and New York City; and the administration of President George W. Bush and the Department of Defense (DOD) had begun shifting major resources of the federal government and military services to a new national priority, homeland defense.