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Frederick DuquesneHow’s this for being a step ahead of the enemy?  Before America ever fired a shot in World War II, the FBI had rolled up a massive ring of Nazi spies operating on U.S. soil—33 in all, ranging from Paul Bante to Bertram Wolfgang Zenzinger.  By December 13, 1941—just six days after Pearl Harbor—every member of the group had either pled guilty or been convicted at trial, including its ringleader Frederick Duquesne.

It all began when a lone German-American refused to give in to Nazi aggression and hatred.  His name was William Sebold, and he served the Allied cause by becoming a double agent for the FBI.

Sebold was a naturalized U.S. citizen who worked in industrial and aircraft plants throughout the U.S. and South America after leaving Germany in 1921.  During a return trip to Germany in 1939, Sebold was “persuaded” by high-ranking members of the German Secret Service to spy on America.  Sebold received espionage training in Hamburg (including how to work a short-wave radio), but not before secretly visiting the U.S. consulate in Cologne and telling officials there that he wanted to cooperate with the FBI.

The FBI was waiting when Sebold returned to New York City in February 1940.  He had been instructed by the Nazis to take on the persona of “Harry Sawyer,” a diesel engineer consultant.  He was then to meet with various spies, pass along instructions to them from Germany, receive messages in return, and transmit them back in code to Germany.
With Sebold’s masterful acting, the FBI played right along with the ruse, using some deceits of their own. Agents secretly filmed the many spies who passed through Sebold’s bogus office

First, the FBI Lab engineers built a secret shortwave radio transmitting station on Long Island.  There, agents pretending to be Sebold sent authentic-sounding messages to his German superiors for some 16 straight months.  Over that time, more than 300 messages were sent and another 200 were received from the Nazis.

Second, the FBI helped set up an office for “Harry” in Manhattan where he could receive visiting spies.  The office was outfitted with hidden microphones and a two-way mirror where the FBI could watch and film everything going on.  With cameras secretly rolling, Sebold met with a string of Nazis who wished to pass secret and sensitive national defense and wartime information to the Gestapo.

One of those visitors was Frederick Duquesne, a veteran spy who served as the group’s leader.  In Sebold’s rigged office, Duquesne explained how fires could be started at industrial plants and shared photographs and plans he had stolen from a plant in Delaware describing a new bomb being made in the U.S.

Another one of the spies was preparing a bomb of his own and even delivered dynamite and detonation caps to Sebold.

Once the FBI had enough information to pinpoint the members of the ring and enough evidence for an airtight case, the 33 spies were arrested.  Nineteen quickly pled guilty; the rest were found guilty at trial in the days following the Pearl Harbor attack.


One German spymaster later commented that the ring's roundup delivered "the death blow" to their espionage efforts in the U.S.  FBI Director J. Edgar Hoover called his concerted FBI swoop on Duquesne's ring the greatest spy roundup in U.S. history.

The 1945 film The House on 92nd Street was a thinly disguised version of the Duquesne Spy Ring saga of 1941, but differs from historical fact.  It won screenwriter Charles G. Booth an Academy Award for the best original motion picture story.


New York Times