Operation Anvil (Mau Mau Uprising) authorities. Within 48 hours the British had detained 206 known insurgents. In the following weeks over 50,000 Africans were detained and questioned. Nevetheless, numerous leading figures among the rebels managed to escape from Nairobi into the countryside. The operation ended on 26 May. Operation Anvil marked a turning-point in the British campaign against the Mau Mau. The action left the insurgents mostly isolated in the forested mountains of Nyandarwa and Kirinyaga without access to supplies and the assistance of passive supporters. It proved to be the most sophisticated undertaking of the Kenyan Emergency. In the following weeks Mau Mau activity
Mau Mau Uprising ordered all Mau Mau suspects to be screened. Of the scores of screening camps which sprang up, only fifteen were officially sanctioned by the colonial government. Larger detention camps were divided into compounds. The screening centres were staffed by settlers who had been appointed temporary district-officers by Baring. Thomas Askwith, the official tasked with designing the British 'detention and rehabilitation' programme during the summer and autumn of 1953, termed his system the "Pipeline". The British did not initially conceive of rehabilitating Mau Mau suspects through brute force and other ill-treatment—Askwith's final plan, submitted to Baring in October 1953, was intended