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
Abiodun (Oyo ruler) Adeyemi. A prominent contemporary descendant was Dr. Ameyo Adadevoh. Abiodun (Oyo ruler) Abiodun (reigned 1770–1789) was an 18th-century "alaafin," or ruler, of the Oyo people in what is now Nigeria. Coming to the throne shortly after the Oyo subjugation of neighboring Dahomey, Abiodun soon found himself embroiled in a civil war over the goals of the newly wealthy state. Bashorun Gaha, the empire's prime minister and lord marshal, had used his power to pervert the constitutional terms of abdication in a bid to limit the powers of the "Alaafin" and gain more political power for himself. During Gaha's power play,