The last Imam of Oman, Ghalib Bin Ali, started an uprising in 1954 when the Sultan granted licenses to the Iraq Petroleum Company despite the fact that the largest oil fields lay inside the Imamate. The hostilities were put down in 1955, but the longer conflict would evolve into the Jebel Akhdar rebellion, where Sultan Said bin Taimur relied heavily on continued British military support. Iraq Petroleum, along with its operator of oil exploration, Petroleum Development Oman, was owned by European oil giants including Anglo-Iranian Oil's successor British Petroleum which encouraged the British government to extend their support to the Sultan.