Italo-Turkish War, (1911–12), war undertaken by Italy to gain colonies in North Africa by conquering the Turkish provinces of Tripolitana and Cyrenaica (modern Libya). The conflict upset the precarious international balance of power just prior to World War I by revealing the weakness of Turkey and, within Italy, unleashed the nationalist-expansionist sentiment that guided government policy in the following decades.
Italy took advantage of a period of international uncertainty following the Moroccan crisis of 1911 to achieve its long-desired goal of establishing a colony in North Africa. Using the pretext of the infringement of Italian interests in the two provinces, the Italian government issued an ultimatum to Turkey on Sept. 28, 1911, and on the next day declared war. Italian forces quickly occupied the towns of Tripoli, Darnah (Derna), and Banghāzī (Benghazi), but unexpected resistance on the part of the Muslim population forced the Italian commander General Carlo Caneva to confine operations to the coastal areas. In May 1912 Italian naval forces occupied Rhodes and some of the Dodecanese islands off the Turkish coast, but the war remained at a stalemate until a successful Italian offensive in North Africa from July to October 1912. Turkey, now menaced by the Balkan states, sought peace. By the terms of the Treaty of Lausanne (also called Treaty of Ouchy; Oct. 18, 1912), Turkey conceded its rights over Tripoli and Cyrenaica to Italy. Although Italy agreed to evacuate the Dodecanese, its forces continued to occupy the islands.