FIRE CONTROL
If ships only engaged when they were stationary the range would not change, and it could be found by observation without rangefinders. And even with rangefinders it can never be found at great distances without observation. But ships do not stand still, and when they move the distance between them alters from second to second. If these movements could be (1) ascertained, (2) integrated, and (3) the results impressed upon the sight, change of range would be eliminated, and we should have come back to the conditions in which ships were stationary. Fire control is successful in so far as it succeeds in doing these three things. [Sketches 3 and 4] show the process by which hits are secured, when the conditions are not complicated by changes in the range, that is, if these complications have been eliminated by fire control. The second two illustrate what these complications are. The ships turn away from each other and then turn towards each other.
The [rate graph (6)] shows the effect of these movements on the range and the rate at which it is changing from moment to moment.
The process shown in [Sketches 3 and 4] is called “bracketing.” Two shots are fired at a difference of, say, 800 yards. Observation shows the first to be too short, the second to be too far. The difference is bisected by the third shot. This places the target in one of the halves of the bracket. This half is bisected by the fourth shot, placing the target in a quarter. If an eighth of the bracket is less than the danger space, then the fifth shot must hit.
Range-finding by bracket
In [Sketch 5] the ships keep parallel courses for two minutes. The range does not change. The line in the [graph (6)] is, for these two minutes, horizontal. It is as if both were stationary. When the ships turn the range increases and the graph rises. But the graph is not a straight line but a curve. This shows that the rate also is changing. Each movement of the two ships, whether they keep steady courses or turn, alters the range and the rate. As projectiles take an interval of time to travel from the gun to the target, the range must be forecasted. B, then, cannot engage A unless he knows where A is going to be. He cannot know this until A has settled on a steady course. While A is turning, then he is safe from gunfire except by a chance shot. B cannot engage while he is himself turning unless he can integrate his own movements with A’s. It is this latter difficulty which largely explains the duration of modern actions. At the mean range of each engagement, with ships standing still, Sydney could have sunk Emden in ten minutes; Inflexible and Invincible could have sunk Scharnhorst and Gneisenau in fifteen. But it was ninety minutes before Emden was driven on the rocks, 180 before Scharnhorst sank, and 300 before Gneisenau went under.
The crux of sea fighting, changes of course and speed produce an irregularly changing range
In the ten years preceding the war, Admiralty policy, as shown by the official apology for the Dreadnought design and by the course of naval ordnance administration, had been governed by the purely defensive idea of providing ships fast enough to keep outside of the zone of the enemy’s fire, armed with guns that outranged him. The professed object was to have a chance of hitting your enemy when he had no chance of hitting you. At the Falkland Islands there was given a classic example of the tactics that follow from this conception. On the assumption that twenty-five 12-inch gun hits would suffice to sink each of the enemy’s armoured cruisers, it appeared that in this engagement the 12-inch gun had attained the rate of one hit per gun per 75 minutes. This figure may be contrasted with the one hit per gun per 72 seconds attained by the Severn in her second engagement with the Koenigsberg at the Rufigi. The contrast seems to show that it was only the obsession of the defensive theory that explained contentment with methods of gunnery so extraordinarily ineffective in battle conditions. For the difference in the rate of hitting was almost completely explained by the range being constant at the Rufigi, and inconstant at the Falklands. And the methods of fire control in use were proved at the Falklands to be unequal to finding, and continuously keeping, accurate knowledge of an inconstant range.
Again at the affair of the Dogger Bank, Lion, Tiger, Princess Royal, New Zealand, and Indomitable were in action for many hours against three battle-cruisers and an armoured cruiser, and for perhaps half the time at ranges at which good hitting is made at battle practice; and although two of the enemy battle-cruisers were hit and seen to be in flames they were able, after two and a half hours’ engagement, to continue their retreat at undiminished speed, and only the armoured cruiser, whose resisting power to 13.5 projectiles must have been very feeble, was sunk.
The lesson of Jutland is still more striking, and it is possible to draw the moral with a little greater precision since it has been officially admitted in Germany that Lutzow, Admiral von Hipper’s flagship, the most modern of Germany’s battle-cruisers, was destroyed after being hit by only fifteen projectiles from great guns. It is not clear from the German statement whether this means fifteen 13.5’s and omits to reckon 12-inch shells, or whether there were fifteen hits in all, some of the one nature and some of the other. The latter is probably the case; for we know from Sir David Beatty’s and the German despatches that it was Invincible’s salvos that finally incapacitated the ship and compelled Von Hipper to shift his flag. Lutzow was always at the head of the German line and so was exposed to the fire of our battle-cruisers for nearly three hours. If we assume that she was hit by ten 13.5’s and five 12-inch; if we further assume that the effect of shells is proportionate to their weight; if we take the resisting power of British battle-cruisers, German battle-cruisers (which are more heavily armoured than the British), and all battleships to compare as the figures 2, 3, and 4 respectively; if we further assume that the Fifth Battle Squadron did not come into effective action till the second phase began, and went out of action at 6:30, and that the battle cruisers were in action for three hours, and omit Hood’s squadron altogether, we get the following results: Five German battle cruisers were exposed to seventy-two hours of 13.5 gun fire and to twenty-four hours of 12-inch gun fire, and five German battleships were exposed to forty-eight 15-inch gun hours. Similarly—omitting Queen Mary, Indefatigable, and Invincible, seemingly destroyed by chance shots and not overwhelmed by gunfire—four British battle-cruisers were exposed to thirty-seven 12-inch and sixty 11-inch gun hours, and the Fifth Battle Squadron was exposed to one hundred and eighty 12-inch gun hours. Had both sides been able to hit at the rate of one hit per hour per gun, the Germans, roughly speaking, should have sunk six British battle-cruisers, and the four ships of the Fifth Battle Squadron nearly twice over; the Fifth Battle Squadron should have sunk four German battleships; and the British battle-cruisers seven German battle-cruisers! The number of hits received by the British Fleet has not been published, but it is probably safe to say that the Germans could not have made a quarter of this number of hits, nor the British ships more than a third. It would seem, then, that at most we made one hit per gun per three hours and the Germans one hit per gun per four hours.
At no time, throughout such parts of the action as we are considering, did the range exceed 14,000 yards, and at some periods it was at 12,000 and at others at 8,000. In battle practice not only on the British Fleet but in all fleets, hits at the rate of one hit per gun per four minutes at 14,000 yards have constantly been made. How, then, are we to explain the extraordinary difference between battle practice and battle results? In the former certain difficulties are artificially created, and methods of fire control are employed that can overcome these difficulties successfully. But these methods evidently break down when it comes to the quite different difficulties that battle presents. So far we are on indisputable ground. Whether fire control can be so improved that the difficulties of battle can be overcome, just as the difficulties of battle practice have been overcome is another matter.
The difference between action and battle practice is, broadly speaking, twofold. First, you may have to fight in atmospheric conditions in which you would not attempt battle practice. All long-range gunnery, whether on sea or on land, depends for success upon range-finding and the observation of fire, and as at sea the observations must be made from a point at which the gun is fired, the correction of fire becomes impossible if bad light or mist prevents the employment of observing glasses and range-finders. In the Jutland despatch particular attention was directed to the disadvantages we were under in the matter of range-finding from these causes. It would appear, then, that those who, for many years, had maintained that the standard service rangefinder would be useless in a North Sea battle, have been proved to be right.
The second great difference lies in the totally different problems which movement creates in battle. In battle practice the only movement of the target is that which the towing ship can give to it. Its speed and manœuvring power are strictly limited, whereas a 30-knot battle-cruiser can change speed and direction at will. The smallest change of course must alter the range, and the smallest miscalculation of speed or course must make accurate forecast of range impossible. But the movements of the target are only a part of the difficulty. Those that arise from the manœuvres of the firing ship may be still greater and more confusing. And so obvious is this that, in peace time, it used to be almost an axiom that to put on helm during an engagement—even for the sake of keeping station—should be regarded almost as a crime. But the long-range torpedo has long since made it clear that a firing squadron may have to put on helm. It must manœuvre, that is to say, in self-defence—a thing it would never have to do in battle practice. And when both target ship and firing ship are manœuvring, it is small wonder if methods of fire control, designed primarily for steady courses by one ship and low speed and small turns by the other, break down altogether. It is undoubtedly true that the mainspring of all defensive naval ideas is doubt as to the success of offensive action, and as the only offensive action that a battleship can take is by its guns, it would seem as if those who disbelieve in the offensive have had far too much reason for their scepticism.