On March 28, 2011, Barack Obama stood behind a presidential podium at the National Defense University and addressed the nation. His ostensible topic was Libya, and his ostensible purpose was to explain his decision to intervene there. And over the course of his 27-minute address, he did this.

Muammar Qaddafi was poised to attack his own citizens. “His forces,” Obama said, “continued their advance, bearing down on the city of Benghazi, home to nearly 700,000 men, women, and children who sought their freedom from fear.” If the United States and its allies had waited, he added, Benghazi could have suffered “a massacre that would have reverberated across the region and stained the conscience of the world.”