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
History of the Kingdom of Dahomey was a significant succession fight after Agaja's death when the recognized heir was passed over for Tegbessou (who ruled from 1740-1774). Tegbessou moved the capital city back to Abomey but had to deal with a number of different factions in the powerful members of the kingdom and in keeping conquered territories loyal. At the same time, the empire continued slave raids throughout the region and became a major supplier to the Atlantic slave trade. In the late 18th century, Oyo put pressure onto Dahomey to reduce its participation in the slave trade (largely to protect its own slave trade) and