The United States invaded Afghanistan on October 7th, 2001 and remains embroiled in the conflict almost two decades later, making this the longest war in US history. Leaders from both of the dominant political parties continually argued that this was a winnable war, proposing new strategies, more troops, and more surges. Yet documents obtained by The Washington Post show that the long-running internal conversations painted a different -- and vastly more disturbing -- picture. Tune in to learn more about the Afghanistan Papers in tonight's Classic episode.