The Bakassi Peninsula at the mouth of the Cross River had been administered as part of Nigeria's Cross River (later Akwa Ibom) State since amalgamation, and historic Efik and Ibibio fishing settlements such as Abana, Atabong and Akwa had been Nigerian-administered for generations. Cameroon's claim rested on the Anglo-German Treaty of 11 March 1913, by which the colonial boundary placed the peninsula in Kamerun. After the 1981 naval clash at Ikang and skirmishes through the 1990s, Cameroon filed suit at the International Court of Justice on 29 March 1994.
On 10 October 2002 the ICJ (Land and Maritime Boundary between Cameroon and Nigeria, Cameroon v. Nigeria: Equatorial Guinea intervening) awarded Bakassi and the Lake Chad islands of Darak and others to Cameroon by 13 votes to 3. Nigeria's coastal Bakassi communities were left without representation. President Olusegun Obasanjo initially rejected the judgment, but under joint UN good-offices mediation he and President Paul Biya signed the Green Tree Agreement at Greentree Estate, New York, on 12 June 2006. The agreement provided for a phased withdrawal of Nigerian forces by August 2008 and for the protection of Bakassi residents' nationality choice and property rights for five further years.
The handover was completed on 14 August 2008 at Abana: Nigerian Brigadier-General Akinade Adekoya lowered the green-white-green flag in a ceremony attended by Cameroonian, Nigerian and UN representatives. Foreign Minister Ojo Maduekwe represented Nigeria. The Senate of the Federal Republic — Senator David Mark presiding — formally protested that the handover was without parliamentary consent under Section 12 of the Constitution; the Bakassi indigenes filed petitions to the ECOWAS Court and the African Commission on Human and Peoples' Rights, which were not successful on substance.
For the Bakassi people the practical consequence was internal displacement to Cross River State settlements (notably the New Bakassi local government area carved out in 2007) and the loss of access to ancestral fishing grounds. For the Nigerian state it remains the largest peaceful loss of de facto territory in the independence era.