The only alternative to directed firing is that of barrage firing, such as is used so greatly in modern land warfare. The defence guns can establish a shell barrage, for a limited period, across any zone which the attacking ship is attempting to penetrate en route to her objective. The vessel which steams into an efficient heavy gun barrage from modern guns is unlikely to survive.
German Coast Defences
I afterwards visited one of the large German batteries near Ostende, called the Jakobynessen battery, which mounted fifteen-inch guns and fired projectiles weighing nearly one ton each—seventeen hundredweight to be precise. They were mounted in specially constructed gun-pits amongst the sand-hills close behind the shore, and were so well hidden that they could not be seen from a distance of little more than a single gun's length. The projectiles stood over six feet high and were murderous-looking instruments of warfare. These particular guns, and there were others of a like nature, could probably have ranged up to sixty thousand yards (over thirty-four land miles).
The whole area off this section of the coast, up to about twenty miles to seaward, was included in the danger zone of the coast batteries. No vessel could maintain her position in that area, under ordinary conditions of visibility, for more than a few minutes at the outside limit. The reader may consider, however, that a ship desiring to attack the coast would merely have to approach in foggy weather or under cover of darkness. In foggy weather she would be unable to locate her objective—so that can be ruled out. At night she might conceivably arrive within a few thousand yards without being seen or heard. But immediately she was located by the defences the latter would fire their star-shell and switch on their searchlights. The whole area would thus be illuminated like daylight. The vessel discovered under such conditions would probably be blown to pieces within five minutes.
Thus it is manifest that ships cannot approach a hostile coast, in the face of modern defences, under the ordinary conditions of daylight or darkness, or in fog.
We will now consider the mine problem. The German mine-fields extended to a distance of several miles from the coast. We had reason to know of their presence; from time to time, as reported in the press, our vessels had been blown up.
Mine-fields off one's own coast provide a certain measure of defence. But they are also an embarrassment in that one's own vessels cannot pass through them, when approaching or leaving harbour, unless safe channels are kept clear for the purpose. This applied to the mine-fields under review.
The German Mine-fields
The reader may possibly have jumped to the conclusion that all we had to do was to navigate calmly through the German safe channels. It certainly sounds plausible. As a matter of fact, such an idea borders on the ridiculous. Let us think this matter out carefully. Our forces could not pass through such channels unless they possessed information as to the positions of those channels. But if such information were received, the chances would be long odds on the information having been "made in Germany." Far from such information being correct, therefore, the positions mentioned would probably be those of the most dangerous mine-fields. Nevertheless, suppose we received information which, from the nature of its source and data, we had every reason to credit; and suppose we acted on such information. Well, on the voyage across the sea, or even before we actually start, the enemy discover that we intend to attack. What will they do? Their argument would be as follows: "The British are coming over to attack us; they may have discovered the positions of our safe channels; we dare not take any chances so we will mine our own safe channels immediately." Mine-layers, kept ready for instant use, would be sent to sea at once. In a very short space of time, probably an hour would be more than sufficient, the previous safe channels would have been converted into areas of the greatest danger.
There are alternative methods which the attackers may adopt. Firstly, they may advance to the attack preceded by a force of mine-sweepers. Now mine-sweeping is a very slow process if it is to be carried out thoroughly. It is inconceivable that a large force of these vessels could steam about, mine-sweeping, near the enemy's coast for a considerable period without being discovered. Their discovery would give the whole show away; the enemy would know that we were approaching; the whole element of surprise would be lost.