thumb|British Army patrol crossing a stream carrying FN FAL rifle (1st and 2nd soldiers from right); Sten Mk5 (3rd soldier); and the Lee–Enfield No. 5 (4th and 5th soldiers) By 1954, Nairobi was regarded as the nerve centre of Mau Mau operations.: "There was an unusual consensus in the ranks of both the military and Baring's civilian government that the colony's capital was the nerve center for Mau Mau operations. Nearly three-quarters of the city's African male population of sixty thousand were Kikuyu, and most of these men, along with some twenty thousand Kikuyu women and children accompanying them, were allegedly 'active or passive supporters of Mau Mau'." The insurgents in the highlands of the Aberdares and Mt Kenya were being supplied provisions and weapons by supporters in Nairobi via couriers.: "In the first months of the emergency the Mau Mau discipline was so strong that a terrorist in the forest who gave his money to a courier could be almost certain of getting what he wanted from any shop in Nairobi." Anvil was the ambitious 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. Those who were not Kikuyu, Embu or Meru were released; those who were remained in detention for screening.
thumb|British Army patrol crossing a stream carrying FN FAL rifle (1st and 2nd soldiers from right); Sten Mk5 (3rd soldier); and the Lee–Enfield No. 5 (4th and 5th soldiers) By 1954, Nairobi was regarded as the nerve centre of Mau Mau operations.: "There was an unusual consensus in the ranks of both the military and Baring's civilian government that the colony's capital was the nerve center for Mau Mau operations. Nearly three-quarters of the city's African male population of sixty thousand were Kikuyu, and most of these men, along with some twenty thousand Kikuyu women and children accompanying them, were allegedly 'active or passive supporters of Mau Mau'." The insurgents in the highlands of the Aberdares and Mt Kenya were being supplied provisions and weapons by supporters in Nairobi via couriers.: "In the first months of the emergency the Mau Mau discipline was so strong that a terrorist in the forest who gave his money to a courier could be almost certain of getting what he wanted from any shop in Nairobi." Anvil was the ambitious 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. Those who were not Kikuyu, Embu or Meru were released; those who were remained in detention for screening.