Answer:
Nigeria became a British protectorate in 1901. The period of colonisation lasted until 1960, when an independence movement succeeded. Nigeria first became a republic in 1963, but succumbed to military rule three years later, after a bloody coup d'état.
First Republic: 1960–1979
British period: 1800–1960
Second Republic: 1979–1983
Fourth Republic: 1999–present