The Infantry units are the principal fighting arms of the Kenya Army. The primary mission of the Infantry formations is to fight and win land battles within area of operational responsibilities in the defence of the nation against land – based aggression, while the secondary mission is the provision of aid and support to civil authorities in the maintenance of order. The Kenya School of Infantry commonly known as S.O.I is located in Isiolo County
In the early 1960s 3rd, 5th, and 11th Battalions of the King's African Rifles (KAR) were based at Nanyuki, Gilgil (seemingly in the same town as a British battalion) and Nairobi (Langata) in rotation.
Timothy Parsons writes:
'..Kenyan political elites viewed the army as a potential source of political leverage. No party or ethnic group was willing to let its rivals gain a dominant position in the armed forces. As a result, veteran askaris worried that politically connected soldiers would replace them. Most of the "martial races" that eomprised the old colonial forces were not part of KANU, and many Kikuyu openly referred to the KAR as the "KADU army." In 1959, the Kalenjin, Kamba, Samburu, and Northern Frontier pastoral communities supplied approximately 77 percent of the total strength of the Kenyan KAR battalions.'
As the country prepared for independence in 1962–63 the National Assembly of Kenya passed a bill (Kenya Bills 1963) to amend the status of Kenyan military forces. Accordingly, former KAR units of them were transformed into Kenyan military forces and the newly independent Kenyan Government was legally empowered to assign names to them. This took effect from the time of the independence ceremonies, midnight, 12 December 1963. Thus 3 KAR, 5 KAR, and 11 KAR became 3 Kenya Rifles, 5 Kenya Rifles, and 11 Kenya Rifles.
Army mutinies in Tanganyika and Uganda in January 1964 set the stage for the unrest that took place within the Kenya Rifles. Faced with many of the same problems that confronted Kenyan soldiers, Tanganyikan and Ugandan soldiers won improved pay and the dismissal of expatriate British officers by threatening their newly sovereign politicians with violence. On the evening of 24 January 1964, the failure of the Kenyan Prime Minister to appear on television, where 11th Kenya Rifles junior soldiers had been expecting a televised speech and hoping for a pay rise announcement, caused the men to mutiny. Parsons says it is possible that the speech was only broadcast on the radio in the Nakuru area where Lanet Barracks, home of the battalion, was located. Kenyatta's government held two separate courts-martial for 43 soldiers.