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Digest form of a Royal Navy circular on fortifications.



In a fortified position on shore, which is intended to direct its fire against ships at sea or against landings, there are at least four different modes of defensive position.
The first is the most simple in concept - the fort is made competent to resist the most modern guns of the day, so that the gunners may work their pieces until the occasion of a direct hit; this means that the fort must be armoured as heavily at least as the most powerful modern ironclads, and is likely to prove prohibitive in cost for all but the most vital batteries.
The second is that the fort is instead a simple earthwork thing, with bomb-proofs to protect against mortars, but which gains the primary protection from being high above the sea - for even the turret ships of the future may not carry their guns more than perhaps thirty feet above the waves without considerable problems with stability, while the same gun atop a modest hill of one hundred and fifty feet may command out to a greater distance and will have fire which plunges down towards the deck of an enemy ship.
The third is the question of land defence - a fort must not be vulnerable to the landing of troops, especially if there is the possibility of an enemy artillery position being established onshore, though it may be lighter to landward than to seaward. For this a fort must be considered as a fort rather than as a series of batteries.
And the fourth is that of placing so many batteries with modest protection that any enemy may not be able to take them all under effective fire. If the Warrior of 20 guns on the broadside were faced with 20 batteries each of which has one gun, then the Warrior may only direct her fire at one or perhaps two batteries at a time while all twenty may direct their fire upon her; even a hit scored only disables one gun, whereas the Warrior hazards all her guns to fortune.

This is not to say that a fort should expect to be able to beat off a full attack. Rather, the purpose of a fortification is to make an area harder to attack; to compel the attacker to expend time and resources on overcoming it; to reduce the number of attacks that the enemy may make as he increases the quality of each one in isolation. Consider the Russian War, where the Russian fortifications in the Baltic Sea protected much of the coastline, not because they were insuperable but because they imposed delays; compare with the American War, where the fortifications present were insufficient to readily fend off ships built to fight off Bomarsund and Kinburn but which did prevent Milne's squadrons from simply sailing upriver. Consider also the attack on Charleston, and how the fortifications there turned what could have been a single frigate demanding satisfaction into a mighty expedition involving two monitors, three ships of the line, four frigates, the Superb and Great Eastern, three mortar gunboats and sundry smaller ships.

The purpose of a fort is not to stop the enemy; it is to make him work harder, much as the cuirass of a heavy cavalryman or the thick wooden sides of a ship of the line are not to stop all attacks but to turn aside weaker ones and to reduce the effect of smaller ones. To this end, forts should aim to be cheap, numerous, strong and able to damage all enemy ships; this combination is of course usually impossible.

The use of the underwater torpedo is of particular interest not because it may stop a determined attack but because of the very great potential for uncertainty. A squadron which knows underwater torpedoes are in use must either move slowly and methodically or risk much damage.



When attacking fortifications, the ideal is to place ships as close as possible to their effective ideal range of fire while also avoiding any gunnery which may damage them. This should influence the designs of forts, which might place water batteries where they may fire upon an enemy that gets too close for the upper tiers to bear or which might even place torpedoes - or the threat of torpedoes - in those places where the guns may not bear.

Fully protecting a fort against Mallet's Mortar is not a necessary level of protection - the performance of the Superb has shown that the big mortar is valuable but inaccurate. It may allow the first breach which dismantles a fort system, but as forts are meant to delay rather than stop an attack this would not cause major problems - the time taken for a Mallet's Mortar to score a hit even upon a comparatively large fort is considerable. It should however be the case that a fort may operate with undiminished coverage with the loss of any one battery and that powder stores be kept in at least two separate places to reduce the risk.