These two protectorates were formally amalgamated into a single entity, the Colony and Protectorate of Nigeria, on January 1, 1914, under Governor-General Sir Frederick Lugard.

The amalgamation of Northern and Southern Nigeria in 1914 was a pivotal moment in the creation of the modern Nigerian state. Driven by administrative efficiency, economic considerations (using the revenue from the more prosperous south to subsidize the north), and the strategic vision of Lord Lugard, the two distinct protectorates were merged. This administrative act marked the official birth of 'Nigeria' as a single political unit under British colonial rule. While the amalgamation streamlined British governance, it also forcibly brought together hundreds of distinct ethnic and cultural groups under a single, artificial boundary. This imposed unity, without a prior shared history of nationhood, laid the groundwork for many of the political and social challenges that Nigeria would face in its post-independence era, as different groups struggled to forge a common national identity within a framework that had been externally imposed.