Ravenna.
Fought 729 between the troops of Leo the Iconoclast, and a force of Italians, raised by Pope Gregory II, in defence of image worship. After a severe struggle, the Greeks were routed, and in their flight to their ships were slaughtered by thousands. It is said that the waters of the Po were so infected with blood, that for six years the inhabitants of Ravenna would not eat any fish caught in that river.