By the late nineteenth century relations between Africans and Europeans in this part of the continent had undergone a complete change. Although Europeans had secured no more than footholds on the coast from which to conduct the Atlantic slave trade, they initiated a spiral of destruction in which African rulers became involved in wars will one another to obtain captives to sell to the slave-traders. In exchange they were given fire-arms which they used in further wars. The abolition of the slave-trade by the European powers in the early nineteenth century helped to bring peace to a ravaged country while at the same time, opening it up to other forms of exploitation. In 1851, for instance, the British signed an anti-slave -trade treaty with the of Lagos, an island just off the West African coast, which was constituted a British colony a decade later. From trading companies could penetrate into the interior and in the course of the next half century the whole of modern Nigeria became a British protectorate in which local rulers were nominally independent but ceded some rights in return for protection from neighbouring states especially the colonies of other European powers. Captain Ambrose appears to have been the first British colonial official to visit Ikere and other small Yoruba states in the interior. By the time Olowe carved his image on the door (18.34), however, Nigeria had been formally designated a colony in which local rulers retained little of their former power. The doors were sent to London to be shown in the British Empire Exhibition of 1924 and were acquired for the British Museum from the ogoga, who commissioned Olowe to carve another pair.