check the direct charge of horsemen became useless, as did
also _chevaux de frise_, though the latter (which originated in the 14th
century) continued to be employed by the Austrians against the
swiftly-charging Turks till the close of the 17th century. Thus it
became necessary to devise some new impediment which, whilst remaining
mobile, would also give cover and an advantage in the final hand-to-hand
shock. The problem was solved in Bohemia, Poland and Moravia (Hussite
wars, about 1420), where, distances being great and the country open,
greater mobility and capacity in the convoys became essential. Great
trains of wagons were placed in charge of an infantry escort, of which a
part had become possessed of firearms, and these moved across country in
as many as twelve parallel lines drilled to form _laagers_, as nowadays
in South Africa. Again the cavalry proved helpless, and for nearly a
century in central Europe the word "_Wagenburg_" (wagon-fortress) became
synonymous with "army." Then an unfortunate inspiration came to the
wagon-men. A large gun was relatively cheaper to manufacture, and more
effective than a small one. To keep their assailants at a distance, they
mounted wall-pieces of about one-inch bore on their wagons. For a moment
the balance inclined in their favour, but the cavalry were quick to see
their advantage in this new idea, and they immediately followed suit.
They, too, mounted guns on wheels, and, as their mobility gave them
choice of position, they were able to concentrate their fire against any
side of the laager, and again ultimate surrender was the only way out of
the defenders' dilemma.

The interesting problem thus raised was never finally solved, for the
scene of action now shifted to western Europe, to the valley of the Po,
and more particularly to the Netherlands, where fortresses were closer
together and the clayey nature of the Rhine delta had already made paved
roads necessary. Then, the _Wagenburg_ being no longer needed for the
short transits between one fortified town and another, the infantry
reasserted themselves. Firearms having been much improved in the
interval the spearmen (pikemen) had already (about 1515) learnt to
protect themselves by musketeers trained to take advantage of cover and
ground somewhat in the same fashion as the modern skirmisher. These
musketeers kept light guns at a distance from their pikemen, but dared
not venture far out, as their fire was altogether inadeq