by Thomas Powers

About the author: Contributing editor to the Los Angeles Times newspaper, Thomas Powers won a Pulitzer prize for his coverage of the 1970 Weatherman bombing incident. He recently published Heisenberg’s War: The Secret History of the German Bomb.

Americans worried that terrorism is about to join the catalog of national ills ought to reflect on March 6, 1970, a date that means nothing to most of them. In New York City on that day, in the basement of a townhouse on a pleasant, tree-lined street in the neighborhood known as Greenwich Village, two men and a woman in their 20s took the first step in what they hoped would be a campaign of relentless and merciless urban terrorism.

Repeated attacks, they hoped, would spark a law-and-order backlash leading, in turn, to revolution, violent overthrow...