5. 1956
The West African Frontier Force was an army formed by the British Colonial Office in 1900 to militarize the West African colonies of Nigeria, Gold Coast, Sierra Leone, and Gambia. They later became recognized as The Royal West African Frontier Force (RWAFF) in 1928. 

Fast-forward to 1956 and, during a visit, the Queen gave the Nigeria Regiment the title of Queen's Own Nigeria Regiment. Here's Queen Elizabeth on that very visit walking past the troop. 

The RWAFF disbanded in 1960 when the colonies gained independence.