"Long before pope Urban II made his ímpassioned plea at Clerrnont, the Italian cities were fighting the Saracens on land and sea. During the four centuries preceeding 1095 they suffered from seemingly endless raids and plunderings; sometimes they allied themselves with the enemy to attack other cities; on occasion they met him with force, and these occasions increased in number and gained in success,
Eventually, in 915 the southern cities, in alliance with Byzantine and papal forces, drove the Saracens from their last stronghold in the peninsula, and a century later the northern cities attacked the various Arab maritime bases nearby. Finally, in the eleventh century the Pisans and
Genoese raided the African coast itself, and forced terms of peace upon the Saracen leader, among them the promise to refrain from further piracy. With this victory and peace, made in 1087, control over the western Mediterranean passed from the Arabs to the Italian cities."
This blog quotes form Baldwin, M. W. (ed.): The first hundred years (1969); source illustration Ceramic Bowl from 1175 -1225 showing Mediterranean ship. From National Museum of San Matteo, Pisa. Source Wikipedia