Britain Annexes Lagos as a Crown Colony
Under the guns of a warship, the Oba of Lagos cedes his island in 1861, giving Britain its first foothold in Nigeria
Quick facts
- Annexation treaty signed
- August 6, 1861
- Oba who ceded Lagos
- Dosunmu (Docemo), under threat of bombardment
- Declared a colony
- 1862
- Prior trigger
- 1851 bombardment deposing slave-trading Oba Kosoko
What happened
In 1861 Britain annexed Lagos, the coastal island port that had been a center of the Atlantic slave trade and a target of British anti-slavery pressure since a naval bombardment in 1851 deposed the slave-trading Oba Kosoko. On August 6, 1861, aboard HMS Prometheus and under the threat of bombardment, Oba Dosunmu (recorded by the British as Docemo) signed a Treaty of Cession transferring sovereignty over Lagos to the British Crown, keeping his title and a pension but losing real power. Lagos was declared a colony in 1862. Scholars describe the consular decade at Lagos from 1851 to 1861 as the first step in the making of Nigeria, foreshadowing many of the issues of the later Scramble for Africa.
Why it matters
Lagos was Britain's first permanent territorial possession in what became Nigeria, the base from which colonial administration and commercial interests pushed inland over the following decades. Its annexation tied the beginnings of British Nigeria directly to the campaign to suppress the Atlantic slave trade, and made Lagos the administrative and commercial hub it remains today.
How we know
The annexation is documented in British consular and Colonial Office records and analyzed in peer-reviewed African-history scholarship on the Lagos Consulate, and it appears in institutional historical accounts of Britain's expansion into Nigeria.
Sources
- The Journal of African History (Cambridge University Press). The Lagos Consulate, 1851-1861: An outline · Peer-reviewed (author-declared)cambridge.org · Cited as a "journal" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- South African History Online. Nigeria · Reputable sourcesahistory.org.za · The domain "sahistory.org.za" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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Related timelines
- The British Empire → · Lagos became Britain's first foothold in Nigeria; the wider expansion of the British Empire in West Africa is covered in the British Empire timeline.