Max Boot, fellow in National Security Studies at the Council on Foreign Relations, talked about his book, Invisible Armies: An Epic History of Guerrilla Warfare From Ancient Times to the Present, in which he presents a history of guerrilla warfare. The author posited that unconventional warfare, often thought of as a modern means of war, has a long tradition that dates back to antiquity. Max Boot spoke at the Heritage Foundation in Washington, D.C.