most influential case was that of Günter Guillaume, which led to the downfall of West German Chancellor Willy Brandt in May 1974. In 1986, Wolf retired and was succeeded by Werner Grossmann. Relationship with Soviet Intelligence Services Although Mielke's Stasi was superficially granted independence in 1957, the KGB continued to maintain liaison officers in all eight main Stasi directorates at the Stasi headquarters and in each of the fifteen district headquarters around the GDR. The Stasi had also been invited by the KGB to establish operational bases in Moscow and Leningrad to monitor visiting East German tourists. Due to their close ties with Soviet intelligence services, Mielke referred to the Stasi officers as "Chekists". In 1978, Mielke formally granted KGB officers in East Germany the same rights and powers that they enjoyed in the Soviet Union. Operations Personnel and recruitment Between 1950 and 1989, the Stasi employed a total of 274,000 people in an effort to root out the class enemy. In 1989, the Stasi employed 91,015 people full-time, including 2,000 fully employed unofficial collaborators, 13,073 soldiers and 2,232 officers of GDR army, along with 173,081 unofficial informants inside GDR and 1,553 informants in West Germany. Regular commissioned Stasi officers were recruited from conscripts who had been honourably discharged from their 18 months' compulsory military service, had been members of the SED, had had a high level of participation in the Party's youth wing's activities and had been Stasi informers during their service in the Military. The candidates would then have to be recommended by their military unit political officers and Stasi agents, the local chiefs of the District (Bezirk) Stasi and Volkspolizei office, of the district in which they were permanently resident, and the District Secretary of the SED. These candidates were then made to sit through several tests and exams, which identified their intellectual capacity to be an officer, and their political reliability. University graduates who had completed their military service did not need to take these tests and exams. They then attended a two-year officer training programme at the Stasi college (Hochschule) in Potsdam. Less mentally and academically endowed candidates were made ordinary technicians and attended a one-year technology-intensive course for non-commissioned officers. By 1995, some 174,000 inoffizielle Mitarbeiter (IMs) Stasi informants had been identified, almost 2.5% of East Germany's population between the ages of 18 and 60. 10,000 IMs were under 18 years of age. From