Muhammad III as-Sadiq (; 7 February 1813 – 27 October 1882) commonly known as Sadok Bey (), was the Husainid Bey of Tunis from 1859 until his death. Invested as Bey al-Mahalla (Heir Apparent) on 10 June 1855, he succeeded his brother Muhammad II ibn al-Husayn on 23 September 1859. Named as divisional General in the Imperial Ottoman Army on 10 June 1855, he was promoted to the rank of Marshal on 10 December 1859. Reign In July 1860, the Bey was persuaded by the British consul, Richard Wood, to allow a British subject named Holt to set up the first official printing press, as well as the first Arabic-language newspaper in the country, the ar-Ra'id at-Tūnisi. A telegraph concession was established, with a French interest taking it up in 1859. On 23 April 1861 he promulgated the first written constitution in the Arab world, separating executive, legislative and judiciary powers, through a new Supreme Council, legislature and court system, thus limiting the powers of the Bey. This constitution guaranteed equality of rights to Muslims, Christians (effectively, therefore, to Europeans) and to Jews; in particular, concerning the right to own property. This created a new legal environment which encouraged Europeans to set up businesses in Tunisia; thus new French traders appeared, along with non-Muslim religious schools. On 26 April 1861, the Bey changed the order of succession to the throne; henceforth it would be the oldest prince in the beylical family who would inherit, rather than the oldest son of the late sovereign. Since the time of Hammouda Pasha two hundred years before, French interests in Tunisia had been housed in the fondouk des Français, a caravanserai in the medina. Now the Tunisian government had a new French consulate built, on what was to become the Avenue de la Marine (now Avenue Habib Bourguiba), and it was formally opened by the Bey on 12 January 1862. The Bey commissioned the Marseille engineer Colin to repair the Zaghouan aqueduct providing a fresh water supply to the capital. In 1865 he began demolishing the walls around the medina, some of which were so unsound they threatened to collapse. It is during this period that Tunis lost a number of its historic gates - Bab Cartagena, Bab Souika, Bab Bnet and Bab El Jazira. The bronze cannon on the city walls and the fortifications of La Goulette were sold off in 1872. Europeans