From its 1886 Royal Charter the Royal Niger Company excluded the Brass (Nembe) trading houses from the Niger above Akassa under penalty of seizure. By 1894 the Nembe — who had no alternative trade and whose population had collapsed from c. 20,000 to c. 8,000 in five years through starvation — were dying out. King Frederick William Koko Mingi VIII (a Christianised chief who reverted to traditional religion in 1894 to lead the war) petitioned the new Niger Coast Protectorate Consul Sir Claude MacDonald in 1894; MacDonald asked the RNC to relax the blockade. The Company refused.
On the night of 28–29 January 1895 Koko led between 1,000 and 1,500 Nembe warriors in roughly 30 war-canoes down the Brass River and across to the RNC headquarters at Akassa. The depot was sacked, the armoury seized, 24 staff (predominantly Krio and Sierra Leonean clerks) killed, and 60 captives — including the Acting Agent-General — taken back to Nembe. Most of the prisoners were ransomed; about 40 were ritually killed at the Nembe juju shrine over the following weeks.
The Royal Navy retaliated on 20–22 February 1895 with a punitive expedition under Rear-Admiral Bedford that bombarded the Nembe towns of Sacrebreche, Fishtown and Twon-Brass. About 200 Nembe were killed by shellfire; the smallpox epidemic that followed killed several thousand more. A subsequent Parliamentary Inquiry (the Kirk Report of 1896) found that the RNC's commercial monopoly was the proximate cause of the raid; the Charter was revoked on 1 January 1900 and the territory transferred to the Crown as the Protectorate of Northern Nigeria. Koko refused to surrender and committed suicide in exile in 1898. The Akassa Raid is the largest armed African revolt against a chartered company in West African history.