Morasses, that is, impassable swamps, which are only traversed by a few
embankments, present peculiar difficulties to the tactical attack, as
we have stated in treating of the defence. Their breadth hardly ever
admits of the enemy being driven from the opposite bank by artillery,
and of the construction of a roadway across. The strategic consequence
is that endeavours are made to avoid attacking them by passing round
them. Where the state of culture, as in many low countries, is so great
that the means of passing are innumerable, the resistance of the
defender is still strong enough relatively, but it is proportionably
weakened for an absolute decision, and, therefore, wholly unsuitable
for it. On the other hand, if the low land (as in Holland) is aided by
inundations, the resistance may become absolute, and defy every attack.
This was shown in Holland in the year 1672, when, after the conquest
and occupation of all the fortresses outside the margin of the
inundation, 50,000 French troops became available, who,—first under
Condé and then under Luxemburg,—were unable to force the line of
inundation, although it was only defended by about 20,000 men. The
campaign of the Prussians, in 1787, under the Duke of Brunswick,
against the Dutch, ended, it is true, in a quite contrary way, as these
lines were then carried by a force very little superior to the
defenders, and with trifling loss; but the reason of that is to be
found in the dissensions amongst the defenders from political
animosities, and a want of unity in the command, and yet nothing is
more certain than that the success of the campaign, that is, the
advance through the last line of inundation up to the walls of
Amsterdam depended on a point of such extreme nicety that it is
impossible to draw any general deduction from this case. The point
alluded to was the leaving unguarded the Sea of Haarlem. By means of
this, the Duke turned the inundation line, and got in rear of the post
of Amselvoen. If the Dutch had had a couple of armed vessels on this
lake the duke would never have got to Amsterdam, for he was “_au bout
de son latin._” What influence that might have had on the conclusion of
peace does not concern us here, but it is certain that any further
question of carrying the last line of inundation would have been put an
end to completely.
The winter is, no doubt, the natural enemy of this means of defence, as
the French have shown in 1794 and 1795, but it must be a _severe_
winter.
Woods, which are scarcely passable, we have also included amongst the
means which afford the defence powerful assistance. If they are of no
great depth then the assailant may force his way through by several
roads running near one another, and thus reach better ground, for no
one point can have any great tactical strength, as we can never suppose
a wood as absolutely impassable as a river or a morass.—But when, as in
Russia and Poland, a very large tract of country is nearly everywhere
covered with wood, and the assailant has not the power of getting
beyond it, then, certainly, his situation becomes very embarrassing. We
have only to think of the difficulties he must contend with to subsist
his army, and how little he can do in the depths of the forest to make
his ubiquitous adversary feel his superiority in numbers. Certainly
this is one of the worst situations in which the offensive can be
placed.