As a journalist, Peter Osnos tracked the story of America’s ill-fated war in Vietnam as it happened; years later, as an editor and publisher, he worked with historians, scholars, and key participants to reexamine that story. Now, in LBJ and McNamara, Osnos shows how the personal relationship between two of the twentieth century’s most significant and complex public figures—President Lyndon B. Johnson and Secretary of Defense Robert McNamara—played a decisive role in shaping the tragedy of what people in the region still call “the American war.”

Drawing on their own words, Osnos shows that Johnson and McNamara knew that the United States would certainly not prevail in the hopeless war in Southeast Asia almost from the moment they began working together on November 22, 1963, the day President John F. Kennedy was assassinated. Yet they chose to escalate a commitment of fewer than 20,000 advisers in 1963 to a force of more than 536,000 American troops in 1968, fueling a conflict that cost millions of lives, darkened the legacies of four presidential administrations, and took a toll on America’s national self-image and political system that has lasted for more than five decades.

How did it happen? Focusing on the key decision points, Osnos explains how Johnson’s volatility and corrosive insecurity and McNamara’s political naivete help to explain the almost inconceivable errors in judgment that drove and then sustained the Vietnam tragedy. Along the way, Osnos addresses related questions that still haunt American history. How would our engagement in Southeast Asia have been different if President Kennedy had not been murdered? How did the fraught relationship between Johnson and the Kennedy family impact Johnson’s attitude toward the war? Why did McNamara accept the escalation of the Vietnam conflict as inevitable, despite his recognition of its futility? Above all, how and why did two smart and dedicated leaders somehow blind themselves to the war’s horrific moral consequences?

In the words of Robert K. Brigham, author of Is Iraq Another Vietnam?, “We learn something new on almost every page” of LBJ and McNamara. It’s a revelatory and deeply human exploration of the roots of one of the most disastrous episodes in American history, whose impact is still felt today.