T h e irruption of Islam into the basin of the Mediterranean in the seventh century closed that sea to the Christians of the West, but not to all Christians. The Tyrrhenian Sea, it is true, became a Moslem lake, but this was not the fate of the waters which bathed Southern Italy, or of the Adriatic or the Aegean Sea. We have already seen that in these latitudes the Byzantine fleets succeeded in repulsing the Arab invasion, and after the check which it experienced at the siege of Constantinople in 719, the Crescent reappeared no more in the Bosphorus. But the struggle between the two warring faiths continued, with alternations of success and reverse. Masters of Africa, the Arabs were bent on seizing Sicily, which they completely dominated after the capture of Syracuse in 878; but that was the limit of their advance. The south Italian towns, Naples, Gaeta, Amalfi, and Salerno in the west, and Bari in the east, continued to recognise the Emperor at Constantinople, and so also did Venice, which, at the head of
the Adriatic, never had anything seriously to fear from the Saracen expansion.