Chad–Nigeria border
One straight line, about 47 miles long, entirely inside Lake Chad. Its ends were fixed by colonial treaties, one of them by measuring from an iron telegraph pole at the mouth of a river.
Written from cited sourcesLast checked 30 September 2026Suggest a correction
See it on the globe:Chad →Nigeria →
Three empires and a lake
Britain, France and Germany all reached Lake Chad in the 1890s. An Anglo-French declaration of 1890 ran their frontier from Say on the Niger to Barrawa on the lake, but not into it. Later treaties pushed the lines out across the water: an Anglo-German agreement in 1893, Anglo-French conventions in 1898, 1904 and 1906, and a Franco-German convention in 1908. The 1904 convention promised France open-water passage between its territories north-west and south-east of the lake in every season.[1]
After the First World War Britain took the part of German Kamerun next to Nigeria as a League of Nations mandate, including the Northern Cameroons on the lake. Its people voted in a plebiscite to join Nigeria, and the union took effect on 1 June 1961.[1]
Fixing the ends
The northern end was fixed by an Anglo-French agreement of 19 February 1910. Its latitude was taken from an iron telegraph pole at the mouth of the Komadugu Yobe river, at 13°42′29″N, and its longitude by measuring 26,700 metres east along that parallel. The agreement didn’t say which meridians to measure from, so in 1969 the US Geographer could only estimate the longitude at about 13°38′E.[1]
The southern end’s latitude, 13°05′N, dates from the Franco-German convention of 9 April 1908, and an Anglo-French exchange of notes in 1931 took it as the meeting point of the old British, French and German lines. Between the two ends the border is simply a straight line.[1]
Timeline
18905 August 1890
Say–Barrawa line
Britain and France divide their spheres up to the lake shore.[1]
19089 April 1908
Franco-German convention
The 13°05′N parallel is set in the lake.[1]
191019 February 1910
Telegraph pole
The northern end’s latitude is fixed.[1]
1960
Independence
Chad on 11 August, Nigeria on 1 October.[1]
19611 June 1961
Northern Cameroons joins Nigeria
The former British mandate on the lake becomes part of Nigeria.[1]
More borders
Sources
- [1]International Boundary Study No. 90: Chad – Nigeria Boundary · US Department of State, Office of the Geographer · 1 October 1969
Map geometry from Natural Earth via world-atlas. See credits.