aggrandisement left Europe at the mercy of uncivilised invaders. In the
ninth and tenth centuries, medieval society experienced the same ordeal
to which the Roman Empire had been subjected in the fifth. From the
North and from the East a new generation of barbarians, perceiving the
patent signs of weakness, began to break through the frontiers in search
of plunder and of settlements.

First came the Northmen from Norway and Denmark. Like the Saxons of the
fourth century they were unrivalled seamen. Their fleets transported
them from point to point faster than land forces could follow in pursuit;
the great rivers served them as natural highways; and if beaten in a
descent upon the land, they had always their ships as a safe refuge. To
make treaties and to offer blackmail was a worse than useless policy;
the Vikings came in bands which operated separately, or united in this
year to scatter and form new combinations in the next. One leader could
not bind another; to buy off one fleet was merely to invite the coming
of a second. These pirates had begun to molest the British Isles and
Frisia before the death of Charles the Great; but after the first
partition of his Empire they fell on the whole coastline from the Elbe
to the Pyrenees. Originally attracted by the hope of plunder they soon
aimed at conquest; when, at the close of the ninth century, there was a
sudden pause in the flood of armed emigration from the North, the
Danelaw in England and Normandy on the opposite side of the Channel
remained as alien colonies which the native rulers were obliged to
recognise.

It was in Gaul that the ravages of the Normans were most severely felt,
though for a few years they were the scourge of Frisia and the adjacent
provinces. Germany and Italy had other enemies to fear. In the year 862
a new danger, in the shape of the Hungarians, appeared on the borders of