"10.30 A.M.: A mine was exploded close to the boat. The explosion was violent, but no damage was done to the hull. After this explosion the boat was much freer than before, and in the hopes that further attempts to blow up the boat might result in completely freeing her,[ [2] I decided to remain submerged at a good depth till after dark, when it might be possible to come to the surface and clear the obstruction. Burned all confidential papers.
"By 2 P.M. battery power was much reduced and further attempts to get clear were given up for a time.
"6.40 P.M.: A mine was exploded a few feet from the hull; the explosion was very violent—electric lights and other small fittings being broken. The motors were at once started in the hope that the net had been destroyed; but this was not the case. The presence of enemy craft on the surface having made it impossible to come to the surface after dark and so clear the obstruction, I decided to come up and remove the crew from the boat before blowing her up. The boat was brought to the surface without difficulty, and when the conning-tower was above water Lieutenant Scaife went on deck to surrender the crew. Fire was immediately opened on him from light guns on shore and three motor-boats which were lying round 'E 7.' As soon as the excitement had died down and the enemy officers had regained control of their men, two motor-boats came alongside and the officers and men were taken off without difficulty. This operation was carried out under the orders of German submarine officers. The boat was sunk as soon as she was clear of men, and a time-fuse having been fired, subsequently blew up.
"Throughout the day the discipline and behaviour of the crew was excellent. This was particularly noticeable at the time of the third explosion. At this time the crew had been fallen out from their stations, and many of them were asleep. On being called to their stations every man went quietly to his place, although the violence of the explosion was such as to convince every one that the boat was badly damaged.
"… Petty Officer Sims, L.T.O., was in charge of the after-switchboard, and continued throughout the day to work the starboard motor, although much hampered by smoke and pieces of molten copper, due to the damage received by the motor and starting resistances while freeing the propeller."
Lieut.-Commander Cochrane attempted to escape, but after covering 200 miles was, with Lieut.-Commander Stoker of "AE 2," captured ten miles from the coast. They received a year's imprisonment, and on August 18, 1918, Lieut.-Commander Cochrane started his successful trip, accompanied by seven military officers, back to England.
V
I
In 1916 we began to look to Germany to produce something very unpleasant in the way of submarines. We were certain she would follow the obvious course indicated by the lessons all belligerents were learning, and produce the big U-cruiser. Very fortunately for us, she produced nothing of the sort until well into 1918, when one small U-cruiser did us a great deal of damage. The point was this—We were worrying and chasing U-boats with trawlers, motor-boats, destroyers, and numbers of other comparatively small and weakly-armed craft. If a U-cruiser, armed with, say, four 6-inch guns, and armoured along her top-strakes, had risen to fight her tormentors—well, it is clear that our small patrol-vessel service would have become suddenly very expensive. Each convoy would have required cruiser protection, and we had not enough cruisers to provide this. In 1917, by our constructor's reckonings, there was no reason why a German submarine could not have been produced which could proceed safely to the East Indies (round the Cape), and repeat (on a bigger scale) the exploits of the Emden. Well, the Germans didn't do it; they produced U-cruisers with two 5·9" guns apiece in 1918, but the type was unsatisfactory and unstable. It is still a puzzle to us that the idea came to them so slowly. We had K-class boats with the fleet in 1916 of 2600 tons, and had shown that a big submarine was a working proposition. (The K boat, of course, is not a cruiser-submarine; she is a fast and lightly-gunned type for use in battle only, and she does not leave the fleet except when detached for watching patrols.) We produced the M-class in 1917, and—for obvious reasons—we kept the type as secret as possible until the Armistice. The M boat is rather smaller than the K, and is of only seventeen knots speed, but she has far better under-water capabilities than her big companion. She carries, besides her torpedo armament, a 12-inch gun of the normal battleship type. This gun can be carried loaded submerged by the use of a watertight tampion and breech. The boat can rise in the wake of an enemy, fire as she "breaks surface," and submerge again—all in a matter of seconds.
The type was extremely successful, and one can only be thankful that such boats were not on the enemy's side. They would have been the very devil to deal with on the trade routes, and would have caused us to reconsider very hurriedly our whole system of anti-submarine defence. Of course, four 6-inch would be better than one 12-inch from a German point of view, especially as a destroyer would be likely to attack unscathed under the fire of one big gun, but our type was intended for use against such things as enemy cruisers, and not for sinking merchant ships. By the end of the war the enemy had arrived at the stage of submarine design where one says, "We've got a type that works—let us stick to it, and just add improvements." We passed that stage before the war and are now in the confident (with reservations!) state of feeling that we can turn out anything required to combine the properties of under-water and surface craft. If submarines continue as weapons of war, they will improve very considerably, and the range of possibility of future types is so great that any prophecy now would be rash. It must be remembered, however, that the depth of water in which a boat is intended to operate limits her size. It is not only that the distance from her keel to periscope is (in the case of a big boat) some 50 feet, but also that the great length of a big boat's hull means that even a slight fore-and-aft inclination as she dives will add enormously to her draught; a very long boat in twenty fathoms of water (the North Sea average) would have to be careful not to get off an even keel, as it might happen that in the presence of the enemy her bow or stern would touch bottom, with the result of causing the whole boat to bounce up to the surface. A submarine submerged is in a state of equilibrium, in that she has little or no tendency to rise or sink if her motors are stopped and the boat left to herself. I am afraid in this history that I continue to speak of submarines as if everybody knew a good deal about them. I use technical expressions and words as if I was dealing with things like motor-cars. I will try and explain more clearly what I mean by "bouncing to the surface," and will do so in the idea that there are probably readers who know as much about diving boats as I do of bimetallism.