Jawhar as-Siqilli

Jawhar (Arabic: جوهر‎‎; fl. 966–d. 992) was a Fatimid general that led the conquest of North Africa and then of Egypt, founded the city of Cairo and the great al-Azhar Mosque. A Christian slave by origin, he was freed by Al-Mu'izz.

Abu al-Hasan Jawhar ibn Abd Allah was originally a Christian from Dalmatia. It was previously suggested that he was Greek or Sicilian. He was brought to Kairouan (now in Tunisia) after being kidnapped by Muslim pirates on the Adriatic. A slave having served several masters, he was granted freedom by Al-Mu'izz, the son of Ifriqiya Caliph Al-Mansur. Soon he was the vizier and the highest-ranking military commander of the Fatimids. In this role he resumed the expansion of the Fatimids and, together with the Zirids, conquered Fez in Northern Morocco, and pushed towards the Atlantic. Only the strongholds of Ceuta and Tangier could be retained by the Umayyads of Córdoba.

After the Western borders had been secured, Jawhar as-Siqilli pushed towards Egypt and occupied the land around the Nile in 969 from the Ikhshidids after a siege at Giza. The conquest was prepared by a treaty with the Ikhshidid vizier Abu'l-Fadl Ja'far ibn al-Fadl (by which Sunnis would be guaranteed freedom of religion), so the Fatimids encountered little resistance. Afterwards Jawhar ruled Egypt until 972 as viceroy.

...
Wikipedia