Mau Mau Uprising more mobile formations that delivered what he termed "special treatment" to an area. Once gangs had been driven out and eliminated, loyalist forces and police were then to take over the area, with military support brought in thereafter only to conduct any required pacification operations. After their successful dispersion and containment, Erskine went after the forest fighters' source of supplies, money and recruits, i.e. the native Kenyan population of Nairobi. This took the form of Operation Anvil, which commenced on 24 April 1954. By 1954, Nairobi was regarded as the nerve centre of Mau Mau operations. Anvil was the ambitious
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