Overview
British authority in the region expanded over roughly half a century, moving from consular influence and trading treaties to the annexation of Lagos, chartered company rule on the Niger, and the declaration of protectorates over the north and south. It was accomplished through a mixture of negotiation, treaty, blockade and military force.
Background and causes
Three pressures came together. Commercial interests wanted secure access to palm oil and other exports and resented the middleman role of coastal traders. Missionary and abolitionist lobbies argued for intervention on moral grounds. And from the 1880s European governments competed for recognised spheres of influence in Africa, formalised at the Berlin Conference of 1884 to 1885, which set rules among European powers for claiming territory without African participation.
Technological and medical changes made inland penetration easier than it had been earlier in the century, including steam navigation on the Niger and Benue and quinine against malaria.
Course of events
Britain annexed Lagos in 1861, establishing a colony on the site of an existing Yoruba port in what is now Lagos. Consuls and naval officers already exercised influence in the delta, and in the 1880s and 1890s treaties were signed with numerous coastal and inland rulers; the terms recorded in English were often understood differently by the signatories.
The Royal Niger Company, chartered in 1886, administered trade along the Niger until its charter was revoked in 1899. Protectorates were declared over the coastal areas, reorganised in stages as the Niger Coast Protectorate and then the Protectorate of Southern Nigeria, while the Protectorate of Northern Nigeria was proclaimed in 1900 under Frederick Lugard.
Expansion met sustained resistance in many areas. Among the episodes recorded are the deposition and exile of Jaja of Opobo in 1887, the British expedition against Benin in 1897, which included the removal of large quantities of court art now held abroad, the campaigns against the Sokoto Caliphate that ended with the fall of Kano and Sokoto in 1903, and prolonged operations in Cross River, Imo and other areas where authority was dispersed and there was no single ruler to negotiate with. Resistance in parts of the middle belt and the east continued into the 1910s and beyond.
In the north, Lugard governed through existing emirs under what became known as indirect rule, retaining local administration, taxation and Islamic courts under British supervision. In the south the same principle was applied unevenly, and in areas without centralised kingship it produced appointed warrant chiefs with no traditional standing.
Aftermath and legacy
By 1914 two protectorates and the Lagos colony covered most of the present territory, and the frontier with French and German holdings had been fixed by treaty between European powers. Those lines separated communities that had long been linked and enclosed others that had not shared a political system.
Indirect rule left a lasting asymmetry: strong reinforced emirates in the north, and in parts of the south administrative structures that many communities regarded as imposed. Both patterns influenced later politics, and the objects removed during the period, particularly from Benin, remain the subject of restitution discussions today.
Key moments
1861
Britain annexes Lagos, creating a colony on an existing Yoruba port.
1884–1885
The Berlin Conference sets rules among European powers for claiming African territory.
1886
The Royal Niger Company receives its charter to administer trade on the Niger.
1897
A British expedition against Benin removes large quantities of court art.
1900
The Protectorate of Northern Nigeria is proclaimed after the company charter is revoked.
1903
Kano and Sokoto fall to British forces, ending the Caliphate as an independent state.

