Italian colonial policy was abruptly altered with the accession to power of Mussolini's fascist government in October 1922. Mussolini, the one-time critic of colonialism, wholeheartedly endorsed Volpi's policy of military pacification and, although accurate intelligence was lacking in Rome, he fully supported the decisions made in the field by army commanders. The 1923 Treaty of Lausanne between the Allied Powers--including Italy--and Atatürk's new government in Turkey made final the dismemberment of the old Ottoman Empire and provided conclusive international sanction for Italy's annexation of Libya.

The second Italo-Sanusi war commenced early in 1923 with the Italian occupation of Sanusi territory in the Benghazi area. Resistance in Cyrenaica was fierce from the outset, but northern Tripolitania was subdued in 1923, and its southern region and Fezzan were gradually pacified over the next several years. During the whole period, however, the principal Italian theater of operations was Cyrenaica (see fig. 3).

In Idris' absence a hardy but aging shaykh, Umar al Mukhtar, had overall command of Sanusi fighting forces in Cyrenaica, never numbering more than a few thousand organized in tribal units. Mukhtar, a veteran of many campaigns, was a master of desert guerrilla tactics. Leading small, mobile bands, he attacked outposts, ambushed troop columns, cut lines of supply and communication, and then faded into the familiar terrain. Italian forces, under Rudolfo Graziani's command after 1929, were largely composed of Eritreans. Unable to fight a decisive battle with the Sanusis, Graziani imposed an exhausting war of attrition, conducting unremitting search-and-destroy missions with armored columns and air support against the oases and tribal camps that sheltered Mukhtar's men. Troops herded beduins into concentration camps, blocked wells, and slaughtered livestock. In 1930 Graziani directed construction of a barbed-wire barrier 9 meters wide and 1.5 meters high stretching 320 kilometers from the coast south along the Egyptian frontier to cut Mukhtar off from his sanctuaries and sources of supply across the border. The area around the barrier, constantly patrolled by armor and aircraft, was designated a free-fire zone. The Italians' superior manpower and technology began to take their toll on the Libyans, but Mukhtar fought on with his steadily dwindling numbers in a shrinking theater of operations, more from habit than from conviction that the Italians could be dislodged from Cyrenaica.

Al Kufrah, the last Sanusi stronghold, fell in 1931, and in September of that year Mukhtar was captured. After a summary courtmartial , he was hanged before a crowd of 20,000 Arabs assembled to witness the event. With the death of Mukhtar, Sanusi resistance collapsed, and the Italian pacification of Libya was completed. Even in defeat, Mukhtar remained a symbol of Arab defiance to colonial domination, and he was revered as a national hero.