At its height, the Roman Empire stretched from the north of Britain to the desert of Egypt. Emperors were cruel and bent on conquering. Art and architecture flourished, but math and science did not. The idea of the empire began with Julius Caesar, who was killed because he was ruling the government by himself. His adopted son, Octavian, became the first emperor, calling himself Augustus Caesar. The Roman Empire split into two parts, East and West. The West fell in 476. The East, which came to be known as the Byzantium Empire, continued for several hundred years.
Most of the population of the Roman Empire lived within easy reach of the Mediterranean, and the imperial government promoted and protected sea-trade and naval communications between the various parts of the empire. Although it could be relatively dangerous, sea-transport was much faster and much less affecting that over-land carriage. There had been sea-borne commercial empires in the Mediterranean Sea for well over two thousand years before Roman domination.
The Romans worked to keep the sea clear of pirates, to build lighthouses and to construct large and sheltered harbors for the great commercial cities maintained by that trade. One might go so far as to say that the existence of the Roman Empire depended on the unity of the Mediterranean or, as the Romans called it, Mare nostrum, "Our Sea."
Outlying reaches of the empire were connected to the sea by the rivers and streams that flowed into it. The Romans were active in dredging ship channels and in building river ports at likely places - such as London, Paris, Cologne, Vienna, Belgrade and so forth - and maintaining river fleets to maintain security and order on these watery highways.
But the network of water-routes extended even further. The Romans and the native...