Second World War

The SIS of the United Kingdom stationed in Latin America was recalled to home service at the onset of hostilities.

The SIS was replaced by the Special Intelligence Service of the Federal Bureau of Investigation of the United States Department of Justice. During the Second World War the human intelligence work of the service was overshadowed by several other initiatives:

• The cryptanalytic effort undertaken by the Government Code and Cypher School (GC&CS), the bureau responsible for interception and decryption of foreign communications at Bletchley Park.
• The extensive “double-cross” system run by MI5 to feed misleading intelligence to the Germans
• Imagery intelligence activities conducted by the RAF Photographic Reconnaissance Unit (now JARIC, The National Imagery Exploitation Centre).

GC&CS was the source of Ultra intelligence, which was very useful.

The most significant failure of the service during the war was known as the Venlo incident, named for the Dutch town where much of the operation took place. Agents of the German army secret service, the Abwehr, and the Counter-Espionage section of the Sicherheitsdienst (SD), posed as high-ranking officers involved in a plot to depose Hitler.

In a series of meetings between SIS agents and the ‘conspirators’, SS plans to abduct the SIS team were shelved due to the presence of Dutch police. On the night of 8–9 November 1939, a meeting took place without police presence. There, the two SIS agents were duly abducted by the SS.

In 1940, journalist and Soviet agent Kim Philby applied for a vacancy in Section D of SIS, and was vetted by his friend and fellow Soviet agentGuy Burgess. When Section D was absorbed by Special Operations Executive (SOE) in summer of 1940, Philby was appointed as an instructor in the arts of “black propaganda” at the SOE’s training establishment in Beaulieu, Hampshire

In early 1944 MI6 re-established Section IX, its prewar anti-Soviet section, and Kim Philby took a position there. He was able to alert the NKVD about all British intelligence on the Soviets—including what the American OSS had shared with the British about the Soviets.

Despite these difficulties the service nevertheless conducted substantial and successful operations in both occupied Europe and in the Middle East and Far East where it operated under the cover name Interservice Liaison Department (ISLD).