hen
the timbers are large and the work is intended as a part of a primary
defence, it is called a _stockade_; when the stakes are placed at the
foot of the scarp, either horizontally or inclined, they receive the
name of _fraises_.

A _cheval-de-frise_ consists of a horizontal piece of timber armed with
wooden or iron lances, which project some eight or ten feet. It is much
employed against cavalry, and on rocky soils serves as a substitute for
palisades.

_Crows'-feet_ are small wooden or iron forms filled with sharp spikes.
They are thrown, with their points upward, on ground which is to be
passed over by cavalry.

_Mines_ are sometimes used in connection with intrenchments, but more
commonly in the attack and defence of permanent works. They will be
noticed further on.

Fieldworks which are to be occupied for a considerable length of time
will usually have their steeper slopes revetted, and be arranged with
scarp and counterscarp, galleries, traverses, blindages, &c. Such works
hold an intermediary rank between temporary and permanent fortification.

As examples of the importance of field fortifications and of the manner
of organizing them, the reader is referred to the celebrated battle of
Fontenoy, in 1745, where the carefully-arranged intrenchments of Marshal
Saxe enabled the French to repel, with immense destruction, the attacks
of greatly superior numbers; to the battle of Fleurus, in 1690, where
the Prince of Waldeck exposed himself to a most disastrous defeat "by
neglecting the resources of fortification and other indispensable
precautions;" to the battle of Malplaquet, in 1709, where Marshal
Villars, by neglecting to occupy and intrench the farm that closed the
passage between the woods of Sars and Laniere, exposed himself to a
disastrous defeat; to the operations of 1792, where General Custine, by
neglecting to intrench the heights that covered Bingen, as the engineers
had recommended, exposed himself to those terrible disasters which
forced him to a precipitate retreat; to the works of Wervike, which, by
a vigorous resistance on the 10th of September, 1793, saved the Dutch
army from total destruction; to the intrenched camp of Ulm, in 1800,
which for six weeks held in check the victorious army of Moreau; to the
intrenched lines of Torres Vedras, in 1810, which saved from destruction
the English army of Wellington; to the field-defences of Hougomont,
which contributed so much to the victory of Waterloo