The Badagry in Bariga, a suburb of Lagos in Lagos State, is the oldest secondary school in Nigeria, founded on 6 June 1859 by the Church Missionary Society. For decades it was the main source of African clergymen and administrators in the Lagos Colony.

Lagos Colony was a British colonial possession centred on the port of Lagos in what is now southern Nigeria. Lagos was annexed on 6 August 1861 under the threat of force by Commander Beddingfield of HMS Prometheus who was accompanied by the Acting British Consul, William McCoskry. Oba Dosunmu of Lagos resisted the cession for 11 days while facing the threat of violence on Lagos and its people, but capitulated and signed the Lagos Treaty of Cession. Lagos was declared a colony on 5 March 1862. By 1872, Lagos was a cosmopolitan trading centre with a population over 60,000. In the aftermath of prolonged wars between the mainland Yoruba states, the colony established a protectorate over most of Yorubaland between 1890 and 1897. The protectorate was incorporated into the new Southern Nigeria Protectorate in February 1906, and Lagos became the capital of the Protectorate of Nigeria in January 1914. Since then, Lagos has grown to become the largest city in West Africa, with an estimated metropolitan population of over 9,000,000 as of 2011.