The collapse of Old Oyo under Fulani pressure from Ilorin (1835–36) ended the centralised order that had policed the Yoruba interior. The wars that followed — Owu (1820–27), Ijaye (1860–65), the Sixteen Years' War (1877–93) ending at Kiriji — turned Ibadan, Ijebu, Egba, Ekiti and Ijesha into rival war-camps. Slave-raiding for the Atlantic and Saharan markets continued well after British abolition; the Egba, Ijebu and Ibadan economies became dependent on captives traded for European firearms through Lagos and Porto-Novo.
## The Ijaye War (1860–1865) — expanded
The Ijaye War is the pivot between the collapse of Old Oyo and the rise of Ibadan as the dominant Yoruba power. Its trigger was a succession dispute: on the death of *Alaafin* Atiba of Oyo (1859), his son Adelu was installed at the new Oyo (Ago d'Oyo). Custom required Adelu to die with his father; Ibadan supported Adelu's break with tradition, Ijaye — under the *Are-Ona-Kakanfo* Kurunmi, the last holder of the Yoruba generalissimo title — refused to recognise him.
The belligerents. Ijaye (Kurunmi) allied with the Egba of Abeokuta (under *Alake* Okukenu and the Basorun Somoye) and, briefly, with Dahomey. Ibadan (under the *Basorun* Ogunmola and *Balogun* Ibikunle) allied with new Oyo and, tacitly, with the CMS mission and the Lagos Consulate.
The course of the war. Kurunmi's Ijaye army was destroyed at the Battle of Ijaye (March 1862); Kurunmi died shortly after, reportedly by suicide, and Ijaye itself was razed and never rebuilt — its ruins lie north-west of modern Ibadan. The Egba withdrew behind the walls of Abeokuta. The war then continued as the Ijaye–Ikorodu campaign (1862–65), in which Ibadan besieged the Egba supply town of Ikorodu on the northern shore of the Lagos lagoon. On 29 March 1865, Governor John Hawley Glover of Lagos landed a mixed force of Hausa constabulary and Royal Marines at Ikorodu and dispersed the Ibadan camp — the first direct British military intervention in a Yoruba war. Ibadan withdrew; Ikorodu was saved; the war formally ended by exhaustion.
Consequences. Kurunmi's death ended the *Are-Ona-Kakanfo* title as a functioning office (it would be revived only as ceremonial). Ibadan emerged as the paramount military power of the interior and would hold that position until Kiriji (1893). Abeokuta emerged intact but fiscally weakened — a condition Glover exploited in the Ogun Blockade that began the same year (1863) and tightened after the 1867 Ifole. Ijaye's destruction accelerated the flight of Yoruba refugees south into Egba and Ijebu territory, feeding the slave caravans that the Lagos customs house was, officially, in Lagos to suppress.
## After Ijaye
The wars created the conditions for British intervention. The 1861 Lagos Treaty of Cession was signed partly to give Britain a customs base to police the slave trade fuelling the wars. The 1886 Kiriji peace was brokered by the Lagos Colony's Special Commissioner Henry Higgins and the CMS missionary Samuel Johnson, with Britain effectively the arbitrator between Ibadan and the Ekitiparapo alliance. By the time the Royal Niger Company's charter was revoked in 1900, the south-west's military exhaustion meant the colonial map closed almost without resistance west of the Niger.
Nigerians read these wars in two registers: as a Yoruba tragedy (Samuel Johnson's History of the Yorubas), and as the first chapter of the colonial story — the proof that the British did not conquer a unified people but inherited a continent of war-weary city-states. See also the Royal Niger Company charter and the Ogun Blockade.