War with Byzantine
In 345 H, the Fatimid naval fleet inflicted a major defeat on the Byzantines in Italy under the command of Ammar bin Hasan, following several minor entanglements and forcing the emperor Constantine VII (913-959) to pay tribute and send a peace-negotiating embassy to the court of Imam Moiz. Later the Umayyids joined hands with Rome and started a campaign against the Fatimids.
Imam Moiz traveeled to Mehdiya in a huge army and ordered the Fatimi fleets to pursue them under the command of Qaid Joher and Hasan bin Ali, Governor of Sicily. It was no sooner that Rome was inficted with a heavy defeat and they had to flee. The news of the defeat had reached the Umayyids in Spain, who ordered their men to return. Ibn Hani of Spain, one of the famous poets of the Fatimid Era has described with detail in many verses, about the victory of the Fatimi forces.
The emporer later sent gifts and precious tokens of silk and gold to the court of Imam Moiz asking him to return his forces back home and award a peace treaty with Rome. In 356 H, a peace treaty was concluded between the Fatimids and the Byzantines, and accordingly, the Muslims sought the right to impose jizya on the Christian inhabitants of Sicily. This defeat of the Byzantines was indeed celebrated with pomp through out the Islamic world.
Fatimid supremacy on the seas was possible due to their knowledge of astronomy and geography.
The Fatimid Caliphs were great patrons of science and learning, thus encouraging research in astronomy and geography.
There were big observatories in Cairo where scholars could follow the movement of the stars. Ibn Yunus, who worked in these observatories, is considered one of the greatest astronomers of the Islamic World.
An astrolabe (instrument for measuring altitude of the sun and stars at sea) developed in the time of Imam Moiz is still kept in the British Museum in London. Geography formed an important part of the curriculum at the Al-Azhar.
Imam Moiz AS was greatly interested in geography and commended a piece of silk to be made at Tustar in Persia, representing, in gold and colours, a map of the world, which cost him 22,000 Dinars (7).