Secret Intelligence Service, also called the SIS or MI6, is a British government agency responsible for gathering intelligence (information) about foreign governments. The SIS also is involved in counterespionage activities—that is, efforts to prevent foreign enemy spies from obtaining classified (secret) material that could be used to threaten the United Kingdom.
The SIS originated in the Secret Service Bureau, which was established in 1909. The bureau included two divisions—the Foreign Section, which became the SIS, and the Home Section, which became the Security Service, or MI5. The initials MI in the names MI5 and MI6 originally stood for Military Intelligence. The numbers 5 and 6 represented the individual sections of the British War Office. The Home Section engaged in counterespionage activities inside the United Kingdom. At the beginning of World War I (1914-1918), the War Office’s Department of Military Operations took over supervision of the Foreign Section, which became known as MO6(c). In 1916, the name became MI6(c), after responsibility for the organization passed to the newly formed Directorate of Military Intelligence. In 1921, the British government established the SIS, under the Foreign Office’s authority.
During and after World War I, SIS agents gathered intelligence about Germany, which at that time was considered the United Kingdom’s biggest threat. Italy’s invasion of Ethiopia and Germany’s move into Austria, Czechoslovakia, and Poland made SIS efforts even more important. During World War II (1939-1945), the SIS achieved numerous successes against the Germans. It gathered information from intercepted communications and provided Allied leaders with knowledge of German and Italian military capabilities.
The SIS’s usefulness did not end with the Allies’ victory in World War II. It was also active during the Cold War—a period from the late 1940’s to the early 1990’s that was marked by tensions between Communist and non-Communist nations. During this time, the SIS gathered intelligence about the Soviet Union. Since then, the agency has become especially active in efforts to prevent terrorism.
