 The force belonged to the Ministry of National Defence (MfNV) from 1961, and was a service branch of the National People's Army until 1971 when it became directly subordinate to the MfNV.The Border Troops numbered approximately 47,000 personnel at its peak, consisting of volunteers and conscripts, the third-largest Warsaw Pact border guard after the Soviet Border Troops and Poland's Border Protection Troops.The "Grenztruppen"'s main role was preventing "Republikflucht", the illegal migration from the GDR, and were controversially responsible for many deaths at the Berlin Wall.