Lagos Becomes a British Colony

In 1861 Lagos became a British colony. Wikipedia's history of Nigeria describes the background: Lagos, like Badagry, Bonny and Calabar, remained a busy slave-trading port despite British anti-slavery treaties. A struggle over the Lagos throne led Britain to bombard the town in 1851. On 30 July 1861 the acting British consul, William McCoskry, and Commander Bedingfield met King Dosunmu aboard HMS Prometheus; under threat of bombardment, Dosunmu signed the Lagos Cession Treaty.

Britain's interest in Lagos grew out of its campaign against the Atlantic slave trade, which it banned from 1807. According to Wikipedia's history of Nigeria, the West Africa Squadron concluded anti-slavery treaties with coastal rulers, but the Nigerian coast, with its many creeks and channels, was hard to control, and Badagry, Lagos, Bonny and Calabar remained busy slave-trading ports.

In 1841 Oba Akitoye of Lagos tried to end the trade; merchants opposed to the ban deposed him in favour of his nephew Kosoko. Britain intervened in this struggle and bombarded Lagos in 1851. Akitoye's successor, Dosunmu, was pressed in 1861 to accept a treaty of cession, which he signed under threat of bombardment (Wikipedia).

According to the Library of Congress country study, British official opinion was still reluctant to take on tropical colonies: a parliamentary report of 1865 even urged withdrawal from West Africa. Colonial Lagos nevertheless became a busy, cosmopolitan port, and its governors worked in the following decades to impose peace settlements on the warring Yoruba states of the interior.

The Library of Congress country study describes colonial Lagos as a busy, cosmopolitan port with Victorian and Brazilian architecture and a black elite that included English-speakers from Sierra Leone and freed slaves who had returned from Brazil and Cuba; Africans were also represented on the largely appointed Lagos Legislative Council. Lagos became the first base of British power in what is now Nigeria and later the capital of the country, until Abuja replaced it in 1991.