Oyo Empire metropolitan Oyo. This may have been fine in the 15th century when Oyo controlled only its heartland. But to make and maintain farther conquest, the structure underwent several changes. Oyo maintained a semi-standing army of specialist cavalry soldiers called the "Eso", the "Esho" or, formally, the Eso of Ikoyi. These were 70 junior war chiefs who were nominated by the Oyo Mesi and confirmed by the Alaafin of Oyo. The Eso were appointed for their military skill without regard to heritage and were led by the Are-Ona-Kakanfo. After Oyo's return from exile, the post of Are-Ona-Kakanfo was established as the
Yoruba people by Protestants, whose prominent member - Church Mission Society (CMS) based in England made the most significant in-roads into the hinterland regions for evangelism and became the largest of the Christian missions. Methodists (known as Ijo-Eleto, so named after the Yoruba word for "method or process") started missions in Agbadarigi / Gbegle by Thomas Birch Freeman in 1842. Henry Townsend, C.C.Gollmer, and Ajayi Crowther of the CMS worked in Abeokuta, then under the Egba division of Southern Nigeria in 1846. Hinderer and Mann of CMS started missions in Ibadan / Ibarapa and Ijaye divisions of the present Oyo state in