On the 6th of August 1861, Lagos became a British Colony, following a seven-day standoff with the British Navy.
Earlier, Oba Dosumu and his Chiefs had been invited aboard the British Naval Steamer, the Prometheus. While there, Acting Consul. William McCoskry, told him that Her Majesty’s government had decided to occupy Lagos and gave him 48 hours grace to discuss with his Chiefs and sign a Deed of Cession.
On 1st August, McCoskry, Bedingfield (Commander of the Prometheus) and others visited the Oba for a response to their proposition. Dosumu refused to sign, and was less than nice to his visitors.
He accused them of being impostors and they in turn, advised him to reconsider.
Unknown to the Oba, the expatriate community and their African charges had been informed that he would cede Lagos.
Upon his refusal, McCoskry and others adopted a sign-or-we-destroy stance. Prometheus guns were pointed at Lagos Island, a forceful reminder of a bombardment that occurred much earlier in 1851, that caused panic amongst Lagos residents.
Initially, the Oba stalled, but two days later, Dosumu signed the papers whereupon the Prometheus fired a gun salute and the British flag was hoisted.
For about 40 years thereafter, the Colony of Lagos continued to evolve on its own and remained separate and insulated from other neighbouring territories.
The turn of the 20th Century precipitated the end of the insulation that the Colony of Lagos had hitherto enjoyed from neighbouring British territories, and on 16th February, 1906, the amalgamation of the Colony of Lagos with the Protectorate of Southern Nigeria became official, with the renaming of Lagos as Colony of Southern Nigeria under Letters of Patent. An Order in Council of the same date, demarcated the borders of Southern Nigeria from the Atlantic Ocean to the South, French territory to the West, the Protectorate of Northern Nigeria to the North and Northeast and German territory to the East.
In actual fact, the amalgamation process actually started two years earlier, with the appointment of Sir Walter Egerton as both Governor of Lagos and High Commissioner of the Protectorate of Southern Nigeria. The two administrations when fully amalgamated in 1906 became known as the Colony and Protectorate of Southern Nigeria with headquarters in Lagos City. For administration purposes, the territory of the former Colony of Lagos was now designated Western or Lagos Province of the Protectorate of Southern Nigeria.