William Sebold (born Wilhelm Georg Debrowski in Germany) was a naturalized US citizen who helped the FBI break apart the Duquesne Spy Ring in the United States after being coerced into becoming a spy for Nazi Germany prior to World War II.

After having his family in Germany threatened by the Nazis, he agreed to spy for them but immediately told US authorities about the plan and was made a double agent by the FBI. Sebold, along with Fritz Duquesne, recruited 33 agents in the U.S. and then all of them were arrested in 1941, convicted of espionage and sentenced to a total of 300 years in federal prisons.

Sebold served in the German Army during World War I but emigrated to the United States in 1922. He then worked in the industrial and aircraft manufacturing industries in both the U.S. and South America. He became a naturalized U.S. citizen in 1936.

While on an extended return trip to Germany to visit his mother in 1939, Sebold was approached by German intelligence agents about his knowledge of US aircraft factories. He was then visited by a “Dr. Renken” and another man from the Gestapo who asked Sebold to spy on the United States for Germany. As an added “incentive”, Sebold’s family was threatened by the Nazis and they said that if he didn’t cooperate, they’d furnish the US government with reports of his being in jail, something he didn’t report on his naturalization paperwork.

Dr. Renken was in fact, Major Nicholas Ritter of the German Abwehr, the German military intelligence service. Sebold reluctantly agreed after the threats he received. He was sent to Hamburg where he went thru a quick seven-week course on how to operate a shortwave radio and the use of the new “microdot” technology for the passing of secret communications and messages.

Sebold was given the code name “Tramp”, the alias Harry Sawyer, and an Abwehr number A.3549. He was given instructions before leaving for the United States on setting up his network and developing a communications plan.

But Sebold had no intention of spying on his new homeland. He visited the US Consulate in Cologne, Germany under the guise of a lost or stolen passport. Once inside, he demanded to see the Consular General. There he told his story of being blackmailed into spying for Germany.

Sebold told the Consular General he was a loyal American and offered to help them round up the spy ring by becoming a double agent for the FBI. It is important to note, that at this time in U.S. history, the United States had no counterespionage capability in place. But the FBI and the government took Sebold up on his offer. They agreed to help him put together the biggest counterespionage trap in US history.

Sebold sailed for New York City via Genoa, Italy and arrived on February 8, 1940. There with the help of the FBI who sprang into action quickly on this, he set himself up in Manhattan as Harry Sawyer, a diesel engineer consultant with a small office in Times Square, called Diesel Research Company.

But first, they assembled a shortwave radio transmitting station in Long Island. FBI agents pretending to be Sebold/Sawyer 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 Abwehr.

Sebold’s office was no ordinary one in Manhattan, FBI agents quickly set it up with a bank of hidden microphones, and a two-way mirror where the agents could record everything. And every time a German agent appeared in “Sawyer’s” office, FBI agents recorded it all. They brought in blueprints of factories and other sensitive information concerning the United States’ production facilities.

The group’s leader Fritz Joubert Duquesne was a veteran German spy since World War I. During the Second Boer War, he spied for the Boers. Codenamed Dunn by the Abwehr, his cover was that of a journalist for the New York Herald. According to the

Abwehr, Duquesne was the master coordinator for all intelligence gathering operations inside the U.S.

Duquesne was worried about Sebold’s office and that it may be bugged, he asked to meet elsewhere in a public place. And the two exchanged names of German agents in America. Duquesne later discussed bombing an American factory, and how to achieve the maximum damage to it, going so far as to bring explosives and blasting caps into Sebold’s office, all of which was captured by the FBI agents.


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On another visit, he showed detailed descriptions of a new US bomb being developed by the Dupont Plant in Wilmington, Delaware that he had gotten by secretly entering the facility.

Sebold kept his cool and played his part through all of this perfectly, working in concert with the FBI until the bureau had enough information to move. And once they did, they moved quickly. All 33 German agents were quickly arrested in June 1941 and charged with various offenses.

When shown the film of their dealings with Sebold, nineteen of them immediately decided to plead guilty. The other fourteen were tried in Brooklyn Federal District court which began in September 1941 and convicted. The trial finished on 13 December 1941 where the spy ring was sentenced to a total of 300 years in prison. Duquesne, the head of the operation was sentenced to 18 years in prison. Had they been arrested after Pearl Harbor, their sentences may have been much more severe. But since the US and Germany were not at war at the time, they were only sentenced to prison terms.

The counter-espionage operation was the largest and most successful in U.S. history. It smashed the Nazis’ attempt to establish an intelligence apparatus in America and it left them largely in the dark about what was happening in the United States during the war.

The affair took its toll on Sebold who then entered the witness protection program. Letters from his family had him scared that the Nazis would try to take their revenge. He tried his hand at many different professions but continually suffered from depression and manic depression. He died in California in 1970 from a heart attack.

Photos: US Archives

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