|British Empire and allies||Aro Confederacy|
|Commanders and leaders|
| L.T. Col. H.F. Montanaro
Captain A. T. Jackson
Major A. M. N. Mackenzie
Lieutenant-Colonel A. Festing
| Eze (King) Kanu Okoro of Arochukwu
|87 officers and 1,550 soldiers||7,500+ Aro and allied soldiers|
|Casualties and losses|
|About 700–800 British casualties||Heavy casualties|
The Anglo–Aro War (1901–1902) was a conflict between the Aro Confederacy in present-day Eastern Nigeria, and the British Empire. The war began after increasing tension between Aro leaders and British colonialists after years of failed negotiations.
Cause of the war
The Aro Confederacy, whose powers extended across Eastern Nigeria and beyond was challenged in the last decades of the 19th century by increasing British penetration of the hinterland. The Aro people and their allies resisted the penetration which threatened their culture, influence, and sovereignty.
Reasons for the war advanced by Sir Ralph Moore, the British High Commissioner of the Nigerian Coast Protectorate, included:
To put a stop to slave dealing and the slave trade generally with a view to the Slave Dealing Proclamation No. 5 of 1901 being enforced throughout the entire territories as from first of January next; to abolish the Juju hierarchy of the Aro tribe, which by superstition and fraud causes much injustice among the coast tribes generally and is opposed to the establishment of Government. The power of the priesthood is also employed in obtaining natives for sale as slaves and it is essential to finally break it; to open up the country of the entire Aro to civilization; to induce the natives to engage in legitimate trade; to introduce a currency in lieu of slaves, brass rods, and other forms of native currency and to facilitate trade transactions; to eventually establish a labour market as a substitute to the present system of slavery.
The Aro peoples use of divinatory practice in shrines dedicated to the god Ibin Ukpabi, to dominate enslavement activities, was perceived to be contrary to the imperial ambition of British powers, which was the cause of a need to consequently destroy the primary shrine, based at Arochukwu (according to: JI Ross, 2015). 
The Aros knew that British penetration would destroy their economic dominance of the hinterland. They also opposed their religion, Christianity, which threatened their religious influence through their oracle Ibini Ukpabi. The Aro led raids and invasions on communities were conducted in order to undermine British penetration since the 1890s. While the British prepared for the invasion of Arochukwu in November 1901, the Aro launched their last major offensive before the Aro Expedition by British forces. Aro forces led by Okoro Toti sacked Obegu (a British ally) which resulted in 400 people dying. This attack quickened British preparation for their offensive.
Sir Ralph Moore and the Royal Niger Company had planned the attack on the Aros and the Ibini Ukpabi oracle since September 1899 but due to lack of necessary manpower, it was delayed until November 1901. On November 28, Lt. Col. A. F. Montanaro led 87 officers, 1,550 soldiers and 2,100 carriers in four axes of advance to Arochukwu from Oguta, Akwete, Unwuna and Itu on a counter-insurgency campaign. As expected, Aro forces resisted all axes strongly, although they lacked modern weapons. However, Arochukwu was captured on December 28 after four days of fierce battles in and around the city. As a result, the Ibini Ukpabi shrine was allegedly blown up. Battles between British and Aro forces continued throughout the region until spring 1902 when Aro forces were defeated in the last major battle at Bende. The Aro Expedition ended three weeks later.
Result of the war
Some of the Aro leaders, like Okoro Toti, were arrested, tried by tribunals, and hanged. The Aro Confederacy was destroyed and Eze Kanu Okoro (king of Arochukwu), went into hiding but was later arrested. Although Aro dominance crumbled in March 1902, many Aros took part in later resistances against the British in the region such as in Afikpo (1902–1903), Ezza (1905), and other areas where the Aro had a particularly significant presence. The defeat of the Aro did help the British to open up the interior, but serious opposition to British penetration in Igboland clearly did not end with the Anglo–Aro War. In the years that followed, the British had to deal with many other conflicts and wars in various parts of Igboland such as the Nri Conflict (1905–1911), Ekumeku War (1883–1914), Igbo Women's War (1929), etc.
- Battles in the Oguta/Owerri area (November 1901)
- Battles of Esu Itu (December 1901)
- Battles of Arochukwu (December 1901)
- Battle of Edimma (January 1902)
- Battle of Ikotobo (January 1902)
- Battle of Ikorodaka (February 1902)
- Battle of Bende (March 1902)
- Edward Harland Duckworth, ed., Nigeria magazine, issues 140–147 (Cultural Division of the Federal Ministry of Information, Nigeria, 1982), p. 31
- Adiele Eberechukwu Afigbo, The Abolition of the Slave Trade in Southeastern Nigeria, 1885–1950 (University of Rochester Press, 2006), p. 44
- Jeffrey Ian Ross (March 4, 2015). Religion and Violence: An Encyclopedia of Faith and Conflict from Antiquity to the Present. Routledge. p. 23. ISBN 1317461096. Retrieved January 12, 2017.
- http://www.nigerdeltacongress.com/karticles/longjuju.htm[permanent dead link]