branch of the military art, without entering into any professional
discussion of details.

The connection of fortification and strategy may be considered under two
distinct heads: 1st, the choice of sites for constructing fortresses for
defence; 2d, their influence in offensive operations, and the
determination of the question whether they can be passed with safety, or
whether the attacking force will be under the necessity of besieging
them.

The centre and extremities of _a base of operations_ should always be
secured either by natural or artificial obstacles. This base is
generally chosen so that fortifications will be necessary for
strengthening only a part of the line. But if a frontier, like the side
of France towards Belgium, be destitute of natural obstacles, the
artificial means of defence must be proportionally increased. Great care
should be taken that permanent fortifications be made only on such
places as may favor military operations. If otherwise, the troops
detached from the active army for garrisoning them, will only tend to
weaken this force without any corresponding advantages. In this way,
fortifications may become actually injurious to defence. A number of the
European fortresses which were built before the subject of strategy was
properly understood, are now regarded as utterly useless, from their
ill-advised positions.

Whether a fortress may be safely passed with merely blockading or
observing it, depends very much upon the nature of the war, and the
numbers and position of the defensive army. The allies, in 1814,
invading France with a million of soldiers, assisted by the political
diversion of factions and Bourbonists within the kingdom, and treason in