Colonial Nigeria was ruled by the British Empire from the mid-nineteenth century until 1960 when Nigeria achieved independence. Britain annexed Lagos in 1861 and established the Oil River Protectorate in 1884. British influence in the Niger area increased gradually over the 19th century, but Britain did not effectively occupy the area until 1885. Other European powers acknowledged Britain's dominance over the area in the 1885 Berlin Conference.

Southern Nigeria was a British protectorate in the coastal areas of modern-day Nigeria formed in 1900 from the union of the Niger Coast Protectorate with territories chartered by the Royal Niger Company below Lokoja on the Niger River.