Adriatic Sea

   Situated between Italy (q.v.) and the coast of Dalmatia (q.v.), it was the most important east-west trade route prior to the 11th century. Byzantine domination of the Adriatic was tested after 827, when Muslim raiders began their conquest of Sicily (q.v.), launching attacks on coastal towns along the southern Adriatic. In 840 they captured Bari (q.v.), and in 866-867 they besieged Dubrovnik (q.v.), which was saved only when a fleet sent from Constantinople (q.v.) appeared. It was probably in response to such attacks that the theme (q.v.) of Dalmatia was created. However, by the late 11th century Byzantine control slipped away to the Venetians, partly due to a favorable treaty the Venetians signed in 1082 with Emperor Alexios I (q.v.). In return, Alexios got Venetian help against expansion by the Normans (q.v.) in the southern Adriatic (described by Anna Komnene [q.v.] in Book Six of The Alexiad). The growing power of Venice (q.v.) in the Adriatic was further enhanced by the partition of Byzantium after the Fourth Crusade (q.v.). In the 13th century the coastal towns along the Adriatic became a kind of national market for Venice, which, in turn, became the foundation for Venice's further expansion in the eastern Mediterranean (q.v.).