h is one of the most
rapid of rivers. He has exaggerated these advantages; for his epithet of
"impregnable" was decidedly disproved by the bloody events of 1800,
1805, and 1809.

The majority of the European states have frontiers by no means so
formidable as that of the Alps and the Inn, being generally open, or
consisting of mountains with practicable passes at a considerable number
of points. We propose to give a set of general maxims equally
applicable to all cases.

When the topography of a frontier is open, there should be no attempt to
make a complete line of defense by building too many fortresses,
requiring armies to garrison them, and which, after all, might not
prevent an enemy from penetrating the country. It is much wiser to build
fewer works, and to have them properly located, not with the expectation
of absolutely preventing the ingress of the enemy, but to multiply the
impediments to his progress, and, at the same time, to support the
movements of the army which is to repel him.

If it be rare that a fortified place of itself absolutely prevents the
progress of an army, it is, nevertheless, an embarrassment, and compels
the army to detach a part of its force or to make _detours_ in its
march; while, on the other hand, it imparts corresponding advantages to
the army which holds it, covers his depots, flanks, and movements, and,
finally, is a place of refuge in case of need.

Fortresses thus exercise a manifest influence over military operations;
and we now propose to examine their relations to strategy.

The first point to be considered is their location; the second lies in
the distinction between the cases where an army can afford to pass the
forts without a siege, and those where it will be necessary to besiege;
the third point is in reference to the relations of an army to a siege
which it proposes to cover.

As fortresses properly located favor military operations, in the same
degree those which are unfortunately placed are disadvantageous. They
are an incubus upon the army which is compelled to garrison them and the
state whose men and money are wasted upon them. There are many in Europe
in this category. It is bad policy to cover a frontier with fortresses
very close together. This system has been wrongly imputed to Vauban,
who, on the contrary, had a controversy with Louvois about the great
number of points the latter desired to fortify. The maxims on this point
are as follow:--

1. The for