A Byte Out of History - FBI Radio Monitoring in WWII

A Byte Out of History
Not So Public Radio: Gathering Intelligence Over the Airwaves in WWII

10/13/04

As far as the war effort went, 1942 was a big year for radio. The "Voice of America" began broadcasting American-based news of the war throughout Europe. Armed Forces Radio was launched to boost the morale of soldiers around the world.

And, on October 9, on a small farm outside Clinton, Maryland--some 25 miles southeast of the nation's capitol--the FBI launched its first major radio station.

An FBI radio station? That's right. But it didn't play the hits of Glenn Miller, Harry James, and other top recording artists of the day. It covertly monitored and intercepted Nazi radio traffic, gathering vital bits of intelligence that supported the Allied cause.

We'd actually been using radio monitoring stations to intercept signals from secret Nazi radio networks for more than a year, including at the Clinton site. But with enemy radio traffic growing by leaps and bounds (the Clinton station alone had intercepted nearly a thousand espionage messages by March 1942), more engineering and personnel firepower were needed.

By October 1942, the revamped station was complete. A larger complement of FBI radio operators--both men and women--began working 24/7 to intercept any and all enemy transmissions coming from inside and outside the U.S.

How did the Nazis transmit these messages? Usually via Morse Code over "covert" Nazi stations discovered by the FBI or other agencies. Other times by embedding secret messages in popular German radio programs.

Once intercepted, though, the messages were handled the same way: they were quickly sent via teletype to the FBI Lab, which analyzed and decoded the intercepts.

It was a two-way street. Beyond picking up transmissions, our operators also sent messages of their own: to FBI employees connected via radio networks, of course. But also to Nazi agents. Thinking they were talking to fellow spies, these agents were actually being used to spread disinformation. Once, with the help of a German double agent, we sent the Nazis over 140 bogus messages, many of which were then forwarded to the Japanese government.

With the success of the Clinton operation, the Bureau built more radio facilities. By February 1943, our radio circuits stretched from Juneau, Alaska, to Santiago, Chile, with more than a dozen stations in between. Ultimately, nearly 30 of these radio stations were operating in the western hemisphere.

The wartime dividends? Outing many Nazi agents in the U.S., across South and Central America, and even in Europe; throwing the Axis powers off course with disinformation; and providing key bits of intelligence that were shared with the military, the State Department, and some foreign intelligence agencies.

Links: FBI History
Related Story: Long Island Double Agent