Anti-colonial Somali movement of Sayyid Mohammed Abdullah Hassan that fought Britain and Italy for two decades.
Defeated by a British combined operation (RAF aerial bombardment beginning January 1920 + Somaliland Camel Corps ground assault) which captured the Dervish strongholds including Taleh and Jidali; Sayyid Mohammed Abdullah Hassan fled into the Ogaden but died of influenza on 21 December 1920, ending the movement.
Lewis's classic, revised and reissued by Ohio University Press/James Currey, is the standard history covering the Dervish, British and Italian Somaliland periods.
On the Sayyid and the poetry and politics of the Dervish resistance.