In the earlier part of the eighteenth century Dover Castle appears to have been much neglected, and an engraved view by Buck, published in or about the year 1735, indicates that certain parts of it had become almost ruinous; but in 1779, owing to the war with our colonies, as well as France and Spain, Dover Castle was hastily placed in a state of extra defence in order to resist the threatened invasion by our enemies. The period of the Napoleonic menace saw great improvements at Dover Castle. Much of the underground work on the north side of the castle, as well as in other parts, belongs to this period. Of these and later works it is not necessary to speak in this volume. They belong to defences which are still effective, and at the present moment Dover Castle may be regarded as a fortress of enormous importance in the safe-guarding of our shores. _Folkestone._--No traces remain here of defensive work, but a castle was built in quite early times, by William de Arcis, for the protection of the town. Owing to the fall of the cliffs and the inroads of the sea, this has long since been destroyed. It is probable that there was some kind of protective work near the mouth of the little river which here runs into the sea, but no traces seem to remain. _Saltwood._--Situated about two miles inland from Hythe, this castle can hardly be described as a purely coast fortress, but it is such a valuable example of the mediaeval castles of its time that it deserves special attention. It must be remembered that the typical mediaeval castle, with its elaborate defences, possessed a moral influence out of all proportion to its strategic value. As soon as effective charges of gunpowder were employed the weakness of mere walls of masonry became at once apparent. Explosives were far more effective and disconcerting than battering-rams. Experience extending over many centuries teaches, what has been so thoroughly proved by recent events on the Continent, that offensive tactics are almost invariably preferable to those of a defensive character, even when practised under the protection of the strongest and most elaborate fortifications. Still, as long as the only dangers were starvation and battering-rams, the mediaeval castle was as nearly as possible a perfect form of defence. Saltwood castle furnishes an excellent example of this. [Illustration: FIG. 30. THE GATE-HOUSE, SALTWOOD CASTLE, KENT]