232 THE ROMAN CONQUESTS. [CHAP.

Caesar also was the first Roman commander who led an

army across the Rhine, though he penetrated but

•^ ofSe" a little Wa7 into Germany. The information which

Romans with jie obtained about that country was mainly derived

ermany. . prisoners

whom he captured when fighting against Ariovistus; and in
this way he has accurately recorded the names of a number of
the tribes. He also describes the Hercynian Forest, the mention
of which he says that he had found occurring in the writings
of Eratosthenes and other Greeks; and he attributes to it a
width of nine days' journey, and a length of sixty, reaching from
the confines of the Helvetii along the course of the Danube as
far as Dacia, where it turned towards the north1. There is no
notice, however, in his work of the great rivers of northern
Germany, and it was not until long afterwards that his country-
men obtained an accurate knowledge of that
land- The next R°man general who crossed the
Rhine was Drusus, the stepson of Augustus, who
in the course of three campaigns traversed a great part of its
western districts. In the year 12 B.C. he started from the Island
of the Batavi, as the country between the mouths of the Rhine
and the Meuse was called, and overran the territory of the
Usipetes and Sigambri, which lay higher up on the right bank
of the stream. The following year witnessed his advance to
the Visurgis (Weser), and as far as the land of the Chatti who
lived about its head-waters, where he established a garrison:
and finally his third campaign carried him from this point, which
formed his base of operations, through the territory of the
Cherusci, and after crossing the Visurgis he reached at last
the banks of the Albis (Elbe). But the achievement on which
the fame of Drusus subsequently rested, since it greatly im-
pressed the imaginations of his countrymen, was his navigation
of the Northern Ocean in a Roman fleet, a thing which had
never before been attempted. This took place during the latter
part of his first campaign. Under his directions a canal, which
bore the name of the Fossa Drusiana, was constructed from the
Rhine to the Lake Flevus, a large piece of water, which then
1 B. G.9 6. 24, 25.