The Anglo-Aro War of 1901–1902 was the largest single military operation the British conducted in eastern Nigeria. Its target was the **Aro Confederacy** — the trading and oracular system centred on Arochukwu in present-day Abia State, whose Ibini Ukpabi ('Long Juju') oracle and Aro merchant network had, for over two centuries, structured the long-distance trade of the entire Igbo, Ibibio and Ijaw interior and supplied the bulk of the captives shipped from Bonny, Calabar and Brass.
The expedition was authorised by Sir Ralph Moor, High Commissioner of the Niger Coast Protectorate, in November 1901, under the command of Lt-Col Arthur Forbes Montanaro. The force — 87 European officers, 1,550 African soldiers of the West African Frontier Force, four 7-pounder guns and four Maxim machine guns — moved on Arochukwu in four columns from Oguta, Akwete, Itu and Unwana. After six weeks of fighting along the forest paths, the Aro defenders were broken at the battles of Bende, Edda and Itu; the columns converged on Arochukwu on 24 December 1901; and the Long Juju shrine at Ibini Ukpabi was destroyed with dynamite on 28 December 1901.
The stated British justification was the suppression of the slave trade and of human sacrifice at the oracle. The actual objectives, recorded in Moor's dispatches to the Colonial Office, were three: (a) end the Aro monopoly on long-distance trade so that British and African 'middlemen' could trade directly with the interior; (b) impose direct rule on the eastern hinterland in advance of the Southern Protectorate amalgamation; (c) extract palm-oil production from the interior at fixed colonial prices. The Long Juju was a symbol — its destruction was theatre for the consumption of the southern Igbo. The trade routes were the prize.
The consequences were extensive. The Aro lost their commercial primacy; the eastern hinterland was opened to direct British penetration; the Native Courts under Warrant Chiefs were extended from the riverine towns deep into the interior (with the consequences documented in the Aba Women's War three decades later); and the broader campaign of 'pacification' continued until the Ekumeku, Tiv and Owerri operations of 1904–1914.
The Anglo-Aro War is the moment at which the British state — not the Royal Niger Company, which had been wound up at the end of 1899 — became the direct sovereign of eastern Nigeria. The Crown had taken over on 1 January 1900; the Aro expedition, two years later, was its first major demonstration that the takeover was not paper.