The Second Italo-Senussi War, also referred to as the pacification of Libya, was a conflict that occurred during the Italian colonization of Libya between Italian military forces (composed mainly by colonial troops from Libya, Eritrea, and Somalia) and indigenous rebels associated with the Senussi Order. The war lasted from 1923 until 1932, when the principal Senussi leader, Omar al-Mukhtar, was captured and executed. The Libyan genocide took place during and after the conflict.
Fighting took place in all three of Libya's provinces (Tripolitania, Fezzan, and Cyrenaica), but was most intense and prolonged in the mountainous Jebel Akhdar region of Cyrenaica. The war led to the mass deaths of the indigenous people of Cyrenaica, totalling one quarter of the region's population of 225,000. Italian war crimes included the use of chemical weapons, execution of surrendering combatants, and the mass killing of civilians, while the Senussis were accused of torture and mutilation of captured Italians and refusal to take prisoners since the late 1910s. Italian authorities forcibly expelled 100,000 Bedouin Cyrenaicans, half the population of Cyrenaica, from their settlements, many of which were then given to Italian settlers.