In the age of encryption, computer hacking, WikiLeaks and Edward J. Snowden, the theft of typewritten government documents from an unlocked file cabinet 44 years ago by ordinary citizens may seem quaint.

But on the evening of March 8, 1971, while much of America was distracted by the Muhammad Ali-Joe Frazier fight, burglars broke into the Federal Bureau of Investigation’s office in Media, Pa., and stole files that revealed the bureau’s unlawful surveillance of antiwar activists. Photocopies were mailed anonymously to three major newspapers, including The New York Times, but only The Washington Post published anything from the files.

The uproar that followed was enormous. The F.B.I. director, J. Edgar Hoover, then so powerful that even presidents feared him, was apoplectic. He was behind Cointelpro, short for Counterintelligence Program, which was later revealed to have secretly collected information on civil rights activists and any group the F.B.I. deemed potentially subversive, with the intent to intimidate and disrupt them. The illegal program had been operating since 1956.