The following is from reports of captured U-boat's men:—
"Several prisoners give clear evidence of the fear inspired by the possible presence of Allied submarines submerged when they themselves were on the surface. Besides the probable results of this method of attack, the apprehension of it constitutes a seriously demoralising influence."
From an officer:—
"We knew that for every boat we had working in an area, you had two looking for us."
The latter statement shows an error in the officer's calculations. The odds were very much the other way; but his error shows that moral effect goes for a good deal in war.
In actions between submarines, guns have also been used, as have rifles, pistols, and—at short range in the dark—verbal abuse; but no definite sinkings on either side can be traced to these causes. In our boats it was the rule to attack submerged, if possible—in the U-boats it was rare to find an inclination to pursue a gun-action to its logical end. A submarine, when nearly hit, can refuse action at any time by diving. This, of course, forces the opponent left on the surface to dive also, as it would be unhealthy then to remain on the surface in that locality. Our submarines were always more lightly gunned than the U-boats. Few of them carried more than one small gun—and that one usually an anti-aircraft weapon. This was for two reasons. Firstly, our boats are meant for warship-destroying as opposed to commerce-destroying. The attacking of warships implies speed under water (one should have, roughly, at least half the speed of the class of ship one is after). Big guns are bad for stream-line, and therefore militate against high submerged speed. Secondly, we were supplying guns to Allies, our own Army, and to all our merchant ships and "mystery ships," and the submarines had to take their turn at the supply with the rest.
The British officer always had an inclination to use the ram if he got a chance. A submarine can ram almost anything, and still, as the U.S. Navy puts it, "Get away with it." Our boats have a ten-inch razor-edged cast-steel stem fitted to them for net-cutting and other purposes. They can also, by their system of compartments, stand damage forward to the extent of a crushed bow, as far back as the bow hydroplanes, with no great risk to themselves. Add to these things the delightful idea of being able to thoroughly damage your ship and to be praised instead of court-martialed for the action, and it is obvious that a number of attempts along this line have been made. There is no record of one having been successful to the extent of sinking an enemy, but in some cases U-boats were damaged in this way. A curious case of accidental ramming was that in which "E 50" (Lieutenant-Commander Michell), when diving near the N. Hinder Light-vessel, sighted a periscope close aboard on the bow. A moment later the two boats collided heavily at 25 feet by gauge. "E 50's" Captain, deciding that the other boat was underneath him, put his hydroplanes "hard-to-dive," and flooded tanks with the idea of carrying the enemy to the bottom (at that point 180 feet away) and crushing him. The U-boat, however, broke away, and after showing her stern and conning-tower a moment on the surface, sank again. It was later discovered that the enemy got home damaged. "E 50" came out of the affair with the loss of her port-bow hydroplane and a few dents. On such an occasion, there is no time to inspect your own boat for damage before making up your mind if you should or should not instantly rise to the surface. It is a natural action to bring your own boat up as soon as possible, in case the chance of ever getting her up at all goes by. The Captain of "E 50" acted on the rule that a dead U-boat is a primary consideration, whatever one's natural inclinations may be; his crew, though not consulted, were in full agreement with him.
Again, I must quote an irrelevant incident. There were two of our submarines in the Heligoland Bight patrol, diving in adjacent areas. They both returned to harbour slightly damaged—one under the impression that, while diving at 55 feet, he had been run over by a surface vessel; the other reporting that, while diving at 25 feet, he had bumped over a submarine. On meeting in harbour they found the times of the mysterious collisions tallied to the minute.
In April 1915, the idea of using a fishing trawler as a decoy originated in the Vulcan's flotilla (C-class submarines)—based on Leith. The U-boats had been sinking our fishing-boats at their leisure, and it was clear that if a few U-boats were mysteriously lost on this duty, it would be a discouraging thought for the remainder. It must be remembered that a "missing" boat has a certain moral effect—a boat openly sunk by gun fire, etc., serves only as an example for others to be more careful. If a certain duty or a certain area becomes unhealthy for U-boats without any explanation, it tends to make the enemy chary of sending boats out on similar work, until the matter is cleared up. Hence the secretiveness of the Admiralty during the war on the losses of enemy submarines. Prisoners taken from U-boats were prevented from explaining to anybody how their boats were sunk. It may have been from humanity, or it may have been from the consideration that U-boat prisoners were usually communicative in a useful way, but orders were strict that as many prisoners as possible were to be saved from the water when U-boats were sunk.
The Vulcan's idea was of masterly simplicity. The U-boats found a fishing fleet easy prey; therefore a fishing fleet with a "catch" on it would get results. One trawler of each fleet was to tow, instead of a trawl, a C-class submarine. The submarine would keep well submerged at the end of the hawser, and need not necessarily keep a periscope look-out, in view of the fact that the critical moment for her to slip tow (a tow can be slipped while submerged) would be notified to her by telephone from the trawler's bridge. Submarine "C 24" was the first to show that the theory worked out in practice.