The Battle of Mahiwa between German and British Imperial forces was fought during the East African Campaign of World War I, when South African and Nigerian troops under Lieutenant General Jacob van Deventer engaged a column under German General Paul Emil von Lettow-Vorbeck, at Mahiwa in German East Africa. The Germans inflicted substantial casualties upon Van Deventer's army, forcing it to withdraw. However, the Germans lost a large percentage of their forces, and were ultimately forced to withdraw from their positions and continue their guerrilla war. The battle was noted by the British Official History as the "most disastrous day for the Nigerian Army since the formation of the force" and was called "the most savage battle in the history of African conflict-not excluding Omdurman or any engagement of the Boer War."