Colonial Army in 1946 as an assistant cook. He claimed he was forced to join the Army during World War II and that he served in the Burma Campaign, but records indicate he was first enlisted after the war was concluded. He was transferred to Kenya for infantry service as a private in 1947 and served in the 21st KAR infantry battalion in Gilgil, Kenya, until 1949. That year, his unit was deployed to Somalia to fight the Somali Shifta rebels. In 1952 his brigade was deployed against the Mau Mau rebels in Kenya. He was promoted to corporal the same year, then to sergeant in 1953.
In 1954 Amin was made effendi (warrant officer), the highest rank possible for a Black African in the colonial British Army of that time. Amin returned to Uganda the same year and in 1961 he was promoted to lieutenant, becoming one of the first two Ugandans to become commissioned officers. He was