Nigeria became a federation of four regions during the regime of

Analyze the question: The question asks who was in charge (whose regime) when Nigeria became a federation of four regions. The key is the creation of the Mid-Western Region.

Concept – Nigeria's regional evolution:

• 1946 (Richards Constitution): three regions (North, East, West).
• 1954 (Lyttelton Constitution): Nigeria became a federation of three regions, with Governor-General James Robertson (1955–1960) in office around the end of the colonial period.
• 1960: Independence, with Sir Abubakar Tafawa Balewa as Prime Minister. Nigeria was still three regions.
• 1963: The Mid-Western Region was carved out of the Western Region, making four regions (North, East, West, Mid-West). This happened under Prime Minister Abubakar Tafawa Balewa's government, with Dr. Nnamdi Azikiwe as ceremonial President (Nigeria became a Republic in October 1963).
• 1966: Military rule began, and in 1967 General Gowon created 12 states, ending the regional structure.

Step by step:

1. Four regions existed only in 1963–1967.
2. The government in power at the time was the First Republic, led by Prime Minister Tafawa Balewa.
3. Enahoro and Awolowo were never heads of government at the national level. Awolowo was the Western Region Premier and later opposition leader. Robertson left in 1960. Azikiwe was the ceremonial head of state, while executive power rested with the Prime Minister.

Tip: Remember the sequence: 3 regions up to 1963 → Mid-West created → 4 regions → 1967 Gowon creates 12 states. Link "1963 Mid-West" with "Balewa's government" for quick recall.