The involvement of the British Colony of Kenya in the Second World War (in Swahili: Vita Kuu ya Pili ya Dunia) began with the declaration of war on Nazi Germany by the British Empire in September 1939. Though some fighting with Italian troops occurred in Kenya itself from June 1940 to February 1941, it remained an important economic asset for the Allies and also contributed a significant number of soldiers to fight in the British Army.
Kenya bordered Italian East Africa to the north, and at the start of the war, it was feared that the much larger Italian army would advance into Kenya as it had into British Somaliland. The King's African Rifles (KAR), responsible for the defence of the whole of British-occupied east Africa with the Somaliland Camel Corps and Sudan Defence Force, numbered just 2,900 men in 1939, compared with the 250,000 Italian colonial troops in the region. A drought in 1939-40 and accompanying crop failure, known at the time as the "Famine of the Italian", also encouraged Kenyans from the agricultural Akamba in eastern Kenya, who had not traditionally joined the army in large numbers, to enlist.Enemy aliens in the colony were interned or placed under supervision.
While the feared large-scale invasion did not occur, smaller incursions into Kenya were conducted in concert with similar operations against Sudan. In the summer of 1940, Kenya saw combat between Commonwealth forces and Italy. The first action of the East African Campaign was the Italian bombing of the South Rhodesian air base at Wajir on 13 June.