TheCameroon–Nigeria border is 1,975 km (1,227 mi) in length and runs from thetripoint withChad in the north to theAtlantic Ocean in the south.[1]
The border starts in the north at thetripoint with Chad inLake Chad, proceeding through the lake via an NW-SE straight line down to the estuary of the Ebedi river.[2] The border follows this river as it flows to the south-east, before turning south, proceeding overland in this direction via a series of irregular lines and some small rivers (such as the Kalia).[2] In the vicinity of the parallel 11°30 the border turns to the south-west, turning north-west at the town of Banki, and then south-west through theMandara Mountains andAtlantika Mountains, occasionally utilising rivers such as the Mayo Tiel andBenue. At about the parallel of 6°30 the border shifts to the west, using irregular lines and rivers such as theDonga, before continuing in a south-west direction via various overland lines and rivers (such as theCross andAkwayafe), before entering theBight of Benin just west of theBakassi peninsula.[2]
Britain had (via theRoyal Niger Company) administered the area aroundLagos since 1861 and theOil River Protectorate (Calabar are the surrounding area) since 1884.[3] As Britain expanded into the interior, two colonies were created - theSouthern Nigeria Protectorate and theNorthern Nigeria Protectorate.[2] In 1900 the administration of these areas was transferred to the British government, with the Northern and Southern (including Lagos and Calabar) protectorates united as the colony of Nigeria in 1914.[2] Meanwhile, against the backdrop of theScramble for Africa, Germany had claimed Cameroon (Kamerun) in July 1884.[3][2] The Scramble culminated in theBerlin Conference of 1884, in which the European nations concerned agreed upon their respective territorial claims and the rules of engagements going forward.
In April–June 1885 Britain and Germany signed a treaty outlining a border in the southern areas of Nigeria and Cameroon utilising theRio del Rey and the Cross River.[3][2] The boundary was extended northwards as far asYola in July–August 1886.[3][2] Disagreements as to the location of the rivers mentioned in these treaties led to another treaty on 1 July 1890 modifying the southern section of the boundary, clarified by mutual agreement on 14 April 1893.[3][2] A treaty of 15 November 1893 then extended the boundary north into Lake Chad; this section was clarified in further detail on 19 March 1906.[3][2] The entire boundary was then confirmed by mutual agreement in February–March 1909 and March–April 1913.[3][2]
When theFirst World War broke out in 1914, Britain and Franceinvaded Cameroon and eventually defeated the Germans in 1916. on 22 July 1922,[4] Cameroon became aLeague of Nations mandate, with the vast majority of the colony going to France, and smaller areas along the Nigerian border (Northern Cameroons andSouthern Cameroons, the former split into two sections) in the west to Britain.[3][2] A BritishOrder in Council of 26 June 1923 stated that thenceforth the British mandated areas would be considered administratively to form part of Nigeria.[3] The boundary between the British and French mandates was delimited in 1930 and then finalised on 9 January 1931.[3][2] This mandate/trusteeship arrangement was affirmed by the UN in 1946.[3] On 2 August that same year Britain finalised the border between Northern and Southern Cameroon, which today forms much of theTaraba State section of the border.[3][2]
As the movement for decolonisation grew in the post-Second World War era, Britain and France gradually granted more political rights and representation for their African colonies.[5] Cameroon gained full independence in January 1960, followed by Nigeria in October.[3][2] In February 1961 aplebiscite was held on the future of Britain's Cameroon mandate, as a result of which Northern Cameroons voted to join Nigeria and Southern Cameroon voted to join Cameroon, thereby fixing the border at its current position.[6][7][3]
In 1994 a long-simmering dispute over the ownership of the Bakassi peninsula was forwarded to theInternational Court of Justice, ruling that the territory belonged to Cameroon in 2002.[8] Despite considerable opposition to the ruling within Nigeria, the peninsula was handed to Cameroon during the period 2006–08.[9] Opposition within Bakassi to Cameroonian annexation has led to theBakassi conflict, which has merged to some degree with the widerAnglophone Crisis in the country, with vocal demands for the separation of the former Southern Cameroons asAmbazonia.[10][11] The far north of the border meanwhile has been heavily affected by theBoko Haram insurgency in recent years.[12]
On June 27, 2024, Cameroon and Nigeria reach an agreement during the 20th extraordinary session of their joint commission. Nigeria agrees not to refer the matter to the International Court of Justice to resolve the last remaining disputed border points.[13]
The two main crossings are at Banki (NGA)-Mora (CMR) in the north and Mfum (NGA)-Mamfe (CMR) in the south.[14][15]