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.

Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea to the south in the Atlantic Ocean. It covers an area of 923,769 square kilometres (356,669 sq mi), and with a population of over 230 million, it is the most populous country in Africa, and the world's sixth-most populous country. Nigeria borders Niger in the north, Chad in the northeast, Cameroon in the east, and Benin in the west. Nigeria is a federal republic comprising 36 states and the Federal Capital Territory, where the capital, Abuja, is located. The largest city in Nigeria is Lagos, one of the largest metropolitan areas in the world and the largest in Africa.