Operation Anvil (Mau Mau Uprising) the reserves. The "Grey" grade was made up of prisoners believed to be passive Mau Mau sympatherisers though for whom strong evidence suggesting their true loyalties was lacking. The last category, "Black", was reserved for detainees identified by the hooded informers or the Special Branch of the Kenya Police as potentially violent insurgents or terrorists. A few may have been prosecuted by the government, but most were funneled through the "Pipeline", a system of work camps, decreasing in brutality until an individual was "re-educated" and deemed safe to release on a native reserve. Operation Anvil (Mau Mau Uprising) Operation Anvil
Operation Anvil (Mau Mau Uprising) Mau" movement, had proliferated the Kikuyuland region. On 20 October the colonial governor declared a state of emergency, initiating efforts by the British military to put down the insurgency. The first months of the British campaign were plagued by a lack of discipline, communication, coherent strategy, and useful intelligence and little progress was made against the Mau Mau. An assault on the Naivasha police station and a massacre of civilians in the village of Lari in March 1953 dramatically escalated the conflict. Mau Mau activity also began to surface in the city of Nairobi, which had a large Kikuyu population.