Mau Mau Uprising attempt to eliminate Mau Mau's presence within Nairobi in one fell swoop. 25,000 members of British security forces under the control of General George Erskine were deployed as Nairobi was sealed off and underwent a sector-by-sector purge. All native Kenyans were taken to temporary barbed-wire enclosures, whereafter those who were not Kikuyu, Embu or Meru were released; those who were remained in detention for screening. Whilst the operation itself was conducted by Europeans, most suspected members of Mau Mau were picked out of groups of the Kikuyu-Embu-Meru detainees by a native Kenyan informer. Male suspects were then taken off for
Mau Mau Uprising relocated. Between 320,000-450,000 of them were moved into concentration camps. Most of the remainder – more than a million – were held in "enclosed villages". Although some were Mau Mau guerrillas, most were victims of collective punishment that colonial authorities imposed on large areas of the country. Hundreds of thousands suffered beatings and sexual assaults during "screenings" intended to extract information about the Mau Mau threat. Later, prisoners suffered even worse mistreatment in an attempt to force them to renounce their allegiance to the insurgency and to obey commands. Significant numbers were murdered. Prisoners were questioned with the help of