This was the position when I took over the command of the Grand Fleet on the outbreak of War, and the matter immediately engaged my attention. The “counter” which had usually been favoured by flag officers commanding Fleets up to the date named, had been the obvious one of an attack by our own light cruisers’ torpedo craft on those of the enemy, as the latter advanced to attack. It was difficult to forecast how far such a “counter” would be successful in preventing the destroyers from firing their torpedoes. Much depended on the distance the torpedo could be relied upon to run with accuracy, and on its speed, both constantly increasing figures.
The great number of destroyers possessed by the enemy, the largely increased range of torpedoes, the difficulty which our light cruisers and flotillas might experience in reaching a favourable position for meeting and disposing of the enemy destroyers before the latter could discharge their torpedoes, together with the danger attendant on meeting the enemy’s fleet in weather of low visibility, when a destroyer attack could be instantly and effectively launched before such a “counter” could take place, made it essential to consider other means for dealing with the situation.
Some German documents which came into our possession early in the War proved the importance which the enemy attached to this form of attack, and emphasised the gravity of the question.
It was, of course, fully realised that the question had two sides, and that if our own Battle Fleet was open to this form of attack, that of the enemy was equally so, but as against this there were important considerations to which it was necessary to devote attention.
The first was that the element of chance enters very largely into torpedo warfare of this nature. A flotilla of destroyers attacking a Battle Fleet at long range does so with the idea that a certain percentage of the torpedoes fired will take effect on the ships, the remainder passing between the ships.
Obviously a torpedo fired at a range of 8,000 yards having a speed of 30 knots an hour, or, in other words, of 50 feet per second, is not comparable to a projectile from a gun which has a velocity at 8,000 yards of say 2,000 feet per second. The torpedo may run perfectly straight after discharge, but unless the speed and course of the target have been determined with considerable accuracy, the torpedo will not hit. Let us assume that the target ship X at position A is steaming at 15 knots, and that the destroyer attacks from a favourable position on the bow so that the torpedo with its speed of 30 knots is discharged on a line at right angles to the course of the target at a distance of 8,000 yards (see [diagram]). The target ship will advance 4,000 yards along the line A B whilst the torpedo is running 8,000 yards along the line C D. The time occupied in each case is eight minutes.
It will be seen that if the course of the target ship has been misjudged very slightly, or had been altered during the passage from A to B, the torpedo will pass ahead or astern of it. In that case it might hit instead a ship Z ahead or one Y astern of X.
There are no means available on board a destroyer for determining with any real accuracy either the speed or the course of a ship at a distance of four or five miles. Hence the difficulty, and the reason why torpedoes are fired at a ship a little way down a line of ships, in expectation that one of the ships in the line will be hit.
The object in view is thus rather to “brown” the enemy, and the chances of achieving this object are naturally proportional to the target presented by a ship as compared with the space between adjacent ships.