In 1852 Mohammed es Senussi returned to Mecca, and shortly afterwards he formally excommunicated the Sultan of Turkey. In 1856 he came, for the last time, to Jerabub, ninety miles west of Siwa. He died here three years later and was buried in the tomb in the mosque. At the time of his death his prestige was enormous; pilgrims travelled many thousands of miles to visit Jerabub, and Senussism had spread all over Central and North Africa. The Senussi zawias became rich from the profits of trading and owned large numbers of slaves, also arms and ammunition were imported from Turkey, landed on the Tripoli coast and taken down to the south. One of the greatest authorities on the Senussi estimated their numbers at between one and a half and three millions at the time of the death of Mohammed es Senussi. But their importance as a military factor was not great; being spread over such a vast area they lacked cohesion, and any combined action would be almost an impossibility. Mohammed es Senussi left two sons, Mohammed el Mahdi and Mohammed el Sherif. The former succeeded his father as the leader of the Senussi. He spent a considerable part of his life at Jerabub, acquiring great wealth and strengthening his influence by peaceable penetration. In 1884 he refused to help the Sudanese Mahdi, who appealed to the Senussi for assistance in driving the English out of Egypt. If the Senussi had risen then and joined with the Sudanese the position of Egypt would have been very dangerous. Mohammed el Mahdi died in 1902 and was succeeded by his nephew, Sayed Ahmed, as the son of Mohammed el Mahdi was still a boy. When Sayed Ahmed succeeded, the French were pushing their conquests inland from the coast, and the Turks were also advancing southwards in Tripoli. Sayed Ahmed did all he could to oppose them, but gradually he was forced to retire. One by one the various zawias were occupied, till finally the Senussi chief was driven back to Kufra and Jerabub. In 1911 Sayed Ahmed allied himself to the Turks, although the Senussi had always been at enmity with them, and when the Italians landed on the Tripoli coast the Senussi supported the Turks in the war against the Italians, and when the Turks were finally beaten the Senussi in the interior became once more practically independent. In the summer of 1915 the Senussi were still ostensibly at peace with Egypt and Britain, but the pro-German agents had successfully fomented an anti-British feeling, and the Arabs were being armed and organized by German and Turkish officers who landed in submarines—from Constantinople—evaded the Italians on the coast, and went down south into the Senussi country. The British and Italian alliance was an incentive to the Arabs in Tripoli, who bitterly resented the Italian occupation of their country.