Central African Republic–DR Congo border

France and King Leopold

The Berlin Conference of 1884–85 recognised King Leopold II of Belgium as head of the International Association of the Congo, which became the Congo Free State on 1 July 1885.^[1] A convention with France on 5 February 1885 and a Congo Free State circular that August disagreed about where their lands met north of the Congo River.^[1]

A protocol of 29 April 1887 settled on the river. The Ubangi’s deepest channel (its thalweg) would be the boundary up to latitude 4° N, and beyond that neither side would exercise political action on the other’s bank.^[1] France founded the outpost of Bangui on the Ubangi two years later and pushed north from it into what became the territory of Ubangi-Shari.^[1]

“From its confluence with the Congo the Thalweg of the Oubangi shall form the boundary until its intersection by the 4th parallel of the north latitude.”^[1]

The 1894 line

The agreement of 14 August 1894, in force from 28 December, fixed today’s border. It follows the Ubangi to where the Mbomou and the Uele meet, then the Mbomou to its source, then a straight line to the watershed between the Congo and Nile basins.^[1] The end point on that watershed, now the South Sudan tripoint, was fixed by Britain and France in 1924 and marked with a stone monument.^[1]

Both rivers are full of islands, and the Mbomou meanders sharply. In 1971 the US Geographer noted that no treaty assigned the islands to either side, and that shifts in the rivers’ channels could complicate things.^[1]

Two independent states

Ubangi-Shari became part of French Equatorial Africa. In 1958 it took the name Central African Republic, and it became independent on 13 August 1960. The Belgian Congo had become independent on 30 June 1960, and took the name Democratic Republic of the Congo in 1964.^[1]

The river is also the way out when there is trouble. After violence around the Central African Republic’s election of 27 December 2020, about 24,000 people crossed the Ubangi into DR Congo. At least 15,000 of them reached the village of Ndu, which has 3,500 people, after attacks on Damara and Bangassou on 2 and 3 January 2021.^[2]