From the perspective of this study of victory, the decision to invade Afghanistan in October 2001 is a critical case in the history of American intervention. That decision exists purely in the context of September 11, 2001, the day that four airplanes were hijacked by al Qaeda operatives, who deliberately flew two of them into the two World Trade Center towers in New York City and one into the Pentagon in Washington, D.C. The fourth airplane crashed into a field in Pennsylvania, short of its intended target in Washington, believed to have been the Capitol or the White House. Because some of the attacks were directed against the political leadership in Washington, many in the U.S. government believed that al Qaeda had planned to destroy the center of government and kill the most senior officials. Those attacks – the first on American soil since the raid against Pearl Harbor on December 7, 1941 – killed almost three thousand people.

As the American people and their leaders absorbed the enormity of the terrorist actions and mourned their dead, policymakers in the President George W. Bush administration began developing policies to address terrorism. The principal action was to launch a counterstrike against the Taliban and al Qaeda's leaders, who operated with impunity in Afghanistan under the protection of the repressive Taliban regime.