Chad–Nigeria relations in the late 1970s, clashes occurred around Lake Chad, where both countries hoped to exploit oil reserves. Both also sought to defuse these confrontations, first by establishing joint patrols and a commission to demarcate the boundary across the lake more clearly. Then in the early 1980s, the low level of Lake Chad brought a series of tiny islands into view, leading to further disputes and disrupting long-standing informal trade networks. This relationship was also complicated by Nigeria's own instability in the north, generated by rising Islamic fundamentalism. Thousands of casualties occurred as the result of violent clashes in Nigeria throughout
Colony of Niger Tibesti Cercle ceded to Chad Colony in French Equatorial Africa, and in 1932, the colony of French Upper Volta was divided amongst its neighbors, with the Cercles of Dori and Fada N'gourma ceded to Niger Colony. Niger Colony officials, unlike neighboring Chad, remained loyal to the French Vichy government after 1940, and thus closed its southern border (to Nigeria) and eastern border until 1944. On 31 December 1946 the Military Territories of N'Guigmi and Agadez were ceded to Niger Colony, leaving only Bilma Cercle as the last military-run section of modern Niger. This area in the far north east only