The slave trade was engaged in by European state and non-state actors such as Great Britain, the Netherlands, Portugal and private companies, as well as various African states and non-state actors. With rising anti-slavery sentiment at home and changing economic realities, Great Britain outlawed the international slave trade in 1807. Following the Napoleonic Wars, Great Britain established the West Africa Squadron in an attempt to halt the international traffic in slaves. It stopped ships of other nations that were leaving the African coast with slaves; the seized slaves were taken to Freetown, a colony in West Africa originally established for the resettlement of freed slaves from Britain. Britain intervened in the Lagos Kingship power struggle by bombarding Lagos in 1851, deposing the slave trade friendly Oba Kosoko, helping to install the amenable Oba Akitoye, and signing the Treaty between Great Britain and Lagos on 1 January 1852. Britain annexed Lagos as a Crown Colony in August 1861 with the Lagos Treaty of Cession. British missionaries expanded their operations and travelled further inland. In 1864, Samuel Ajayi Crowther became the first African bishop of the Anglican Church.
In 1885, British claims to a West African sphere of influence received recognition from other European nations at the Berlin Conference. The following year, it chartered the Royal Niger Company under the leadership of Sir George Taubman Goldie. In 1900 the company’s territory came under the control of the British government, which moved to consolidate its hold over the area of modern Nigeria. On 1 January 1901, Nigeria became a British protectorate, and part of the British Empire, the foremost world power at the time. In the late 19th and early 20th centuries the independent kingdoms of what would become Nigeria fought a number of conflicts against the British Empire’s efforts to expand its territory. By war, the British conquered Benin in 1897, and, in the Anglo-Aro War (1901–1902), defeated other opponents. The restraint or conquest of these states opened up the Niger area to British rule.