In December 1955, Sultan Said bin Taimur sent troops of the Muscat and Oman Field Force to occupy the main centres in Oman, including Nizwa, the capital of the Imamate of Oman, and Ibri. The Omanis in the interior led by Imam Ghalib Alhinai, Talib Alhinai, the brother of the Imam and the Wali (governor) of Rustaq, and Suleiman bin Hamyar, who was the Wali (governor) of Jebel Akhdar, defended the Imamate in the Jebel Akhdar War against British-backed attacks by the Sultanate. In July 1957, the Sultan's forces were withdrawing, but they were repeatedly ambushed, sustaining heavy casualties. Sultan Said, however, with the intervention of British infantry (two companies of the Cameronians), armoured car detachments from the British Army and RAF aircraft, was able to suppress the rebellion. The Imamate's forces retreated to the inaccessible Jebel Akhdar.