The capture of Warũhiũ Itote (aka General China) on 15 January 1954 and the subsequent interrogation led to a better understanding of the Mau Mau command structure. Operation Anvil opened on 24 April 1954, after weeks of planning by the army with the approval of the War Council. The operation effectively placed Nairobi under military siege, and the occupants were screened and the Mau Mau supporters moved to detention camps. The Home Guard formed the core of the government's strategy as it was composed of loyalist Africans, not foreign forces like the British Army and King's African Rifles. By the end of the emergency, the Home Guard had killed 4,686 Mau Mau, amounting to 42% of the total insurgents. The capture of Dedan Kimathi on 21 October 1956 in Nyeri signified the ultimate defeat of the Mau Mau and essentially ended the military offensive. During this period, substantial governmental changes to land tenure occurred. The most important of these was the Swynnerton Plan, which was used to both reward loyalists and punish Mau Mau.