Colonial era (1900–1959) — Adamawa State

British conquest of Yola (2 September 1901) — Colonel T.L.N. Morland's WAFF column takes Yola; Lamido Zubeiru flees. Native Authority installed under Bobbo Ahmadu.
World War I — Cameroon border campaign (1914–1916) — Adamawa Province is the launching ground for the British/French invasion of German Kamerun. The Garua and Mora campaigns are fought across what is now Mubi and the Mandara LGAs.
1919 Versailles partition — northern German Kamerun is mandated to Britain as Northern Cameroons and administered from Yola; the new boundary cuts through Bata, Higi and Kilba communities.
Lutheran mission and the Bachama awakening (1923–1959) — the American Lutheran Mission at Numan provides the only sustained Western schooling for Bachama, Bata, Mumuye and Kilba populations and creates the literate non-Muslim class that later carries the Middle Belt political movement.
Northern Cameroons Plebiscite (11 February 1961) — UN-supervised vote in which the Mubi, Madagali, Michika, Gwoza and Adamawa-trust districts choose to join Nigeria. The southern Trust Territory votes to join Cameroon. The boundary remains contested at the local level into the 21st century.