The killing of al Qaeda’s leader, Ayman al-Zawahiri, was America’s biggest counterterrorism victory in years. Like Che Guevara, Zawahiri was a physician who traded saving lives for inspiring others to take them. During medical school and as a young surgeon in Cairo, he joined a series of radical groups in the 1970s and was jailed for his involvement in the 1981 assassination of Anwar Sadat. The lesson he learned in prison, according to his autobiography, “Knights Under the Prophet’s Banner,” was that he wouldn’t have been caught if he could have handpicked his confederates.

He rarely talked about poverty or class oppression, but his autobiography reveals that he studied Lenin’s methods closely. He believed that a small group, a vanguard of enlightened extremists, should direct society while keeping their real aims a secret, and that people, especially in democracies, had to be stampeded by terror to go in his desired directions, not persuaded by reason and evidence.