In 1015 and again in 1016 forces from the taifa of Denia, in the east of Muslim Spain (al-Andalus), attacked Sardinia and attempted to establish control over it. In both these years joint expeditions from the maritime republics of Pisa and Genoa repulsed the invaders and preserved Sardinia as a part of Christendom. These Pisan–Genoese expeditions to Sardinia were approved and supported by the Papacy, making them precursors of the Crusades, which began eighty years later. The victors, however, turned on each other and the Pisans obtained mastery over the island at the expense of their erstwhile allies. For this reason, the major Christian sources for the expedition primarily belong to Pisa, which celebrated its double victory over the Muslims and the Genoese with an inscription on the walls of its Duomo. Denia perhaps hosted a naval squadron under the Caliphs of Córdoba in the tenth century; its port was "very good and very old". According to al-Idrīsī, as quoted in al-Himyarī, its shipyards were important in outfitting its fleet, and these may have been where the fleet launched against Sardinia originated. In 940/1 the Caliphate signed treaties with Amalfi, Barcelona, Narbonne and Sardinia promising safe conduct through those areas until then harassed by pirates based in Fraxinetum, the Balearic Islands and the eastern ports of Spain, the so-called Sharq al-Andalus (including Denia and the famous pirate base of Pechina). There is a recorded embassy from Sardinia to Córdoba in the years immediately following, but from 943 to c. 1000 there are no recorded Muslim attacks on the Christian ports of the western Mediterranean. The Carolingian navy was present in both Pisa and Genoa in the early ninth century. The north Italian cities had sent ships to protect Sardinia from a Muslim fleet in 829, but it was probably a Muslim fleet operating out of Sardinia that raided Rome in 841. The period of the late tenth and early eleventh centuries corresponded with a large growth in Pisa's population and in its geographical extent: its walls and fortifications doubled in scope and its suburbs grew. It entered into frequent territorial disputes with neighbouring Lucca, often violent, and its need for imports grew commensurately. Genoa, with even less hinterland to support its citizens and its shipyards, was also pressured into looking for new markets. The Annales pisani antiquissimi, the civic annals of Pisa compiled by Bernardus Marangonis, record only a few events from the tenth century, and all have to do with the waging of war. In 970 "the Pisans were in Calabria", probably making war on its Muslim occupants in order to secure safe passage for their merchants through the Strait of Messina that separated Muslim Sicily from the peninsula. The Annales also record a Muslims naval attack on Pisa in 1004 and a Pisan victory over the Muslims off Reggio in 1005. The Muslim assault of 1004 may have originated in Spain, or it may have been a typical pirate raid. The Pisan attack was likely a response, and perhaps a serious attempt to put an end to Muslim piracy, for which Reggio served as a perennial base. In 1006 an embassy from the Byzantine emperor Basil II to the court of the caliph Hishām II released some Andalusian soldiers that had been captured off the coasts of Corsica and Sardinia. Together with Sicily, Corsica and Sardinia comprised the "route of the islands" which linked the north Italian towns to the markets of northern Africa and the eastern Mediterranean. Without control of the islands the expansion of Pisan and Genoese mercantile ventures would have been severely hampered. The rise of Pisan and Genoese trading in connexion with increased military activity, especial against the enemies of the Church, has a contemporary parallel on the other side of Italy in the burgeoning Republic of Venice. The taifa of Denia at its peak. In 1011 the Pisan annals record that a "fleet from Spain" came to destroy the city, which suggests that the aggression was planned and organised and not merely a piratical raid. The most probable source of the fleet was the port of Denia, then ruled by Mujāhid al-‘Āmirī (Mogehid). According to the chronicle of Ibn ‘Idhārī, Mujāhid received Denia from the Córdoban hājib Muhammad Ibn Abī ‘Āmir al-Manṣūr, who died in 1002. It is unclear from Ibn ‘Idhārī whether Mujāhid conquered the Balearics from his base at Denia, or whether he took control of Denia from a base in the Balearics. A Muslim enclave was perhaps established by Mujāhid's predecessor as ruler of the Balearics around 1000. Pope John VIII, since Sardinia lay directly across the Tyrrhenian Sea from Rome, urged the Christian lay powers to expel the Muslims from the island in 1004.

• published: 15 Jun 2015
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