'If a pennant is shown in like manner over No. 37, it signifies that ships are to engage on the enemy's larboard side, whether going large or upon a wind.
'These additions to be noted in the Signal Book in pencil only.'[2]
The effect of this memorandum was, of course, that Nelson had it in his power to let every captain know, without a shadow of doubt, under all conditions of wind, on which side he meant to engage the enemy.
To the evidence of the Signal Book may be added a passage in Nelson's letter to Admiral Sir A. Ball from the Magdalena Islands, November 7, 1803. He there writes: 'Our last two reconnoiterings: Toulon has eight sail of the line apparently ready for sea … a seventy-four repairing. Whether they intend waiting for her I can't tell, but I expect them every hour to put to sea.'[3] He was thus expecting to have to deal with eight or nine of the line, which is the precise contingency for which the memorandum provides. There can be little doubt therefore that it was issued while Nelson lay at Magdalena, the first week in November 1803.[4]
The second memorandum, which Nelson communicated to his fleet, soon after he joined it off Cadiz, is regarded by universal agreement as the high-water mark of sailing tactics. Its interpretation however, and the dominant ideas that inspired it, no less than the degree to which it influenced the battle and was in the mind of Nelson and his officers at the time, are questions of considerable uncertainty. Some of the most capable of his captains, as we shall see presently, even disagreed as to whether Trafalgar was fought under the memorandum at all. From the method in which the attack was actually made, so different apparently from the method of the memorandum, some thought Nelson had cast it aside, while others saw that it still applied. A careful consideration of all that was said and done at the time gives a fairly clear explanation of the divergence of opinion, and it will probably be agreed that those officers who had a real feeling for tactics saw that Nelson was making his attack on what were the essential principles of the memorandum, while some on the other hand who were possessed of less tactical insight did not distinguish between what was essential and what was accidental in Nelson's great conception, and, mistaking the shadow for the substance, believed that he had abandoned his carefully prepared project.
For those who did not entirely grasp Nelson's meaning there is much excuse. We who are able to follow step by step the progress of tactical thought from the dawn of the sailing period can appreciate without much difficulty the radical revolution which he was setting on foot. It was a revolution, as we can plainly see, that was tending to bring the long-drawn curve of tactical development round to the point at which the Elizabethans had started. Surprise is sometimes expressed that, having once established the art of warfare under sail in broadside ships, our seamen were so long in finding the tactical system it demanded. Should not the wonder be the converse: that the Elizabethan seamen so quickly came so near the perfected method of the greatest master of the art? The attack at Gravelines in 1588 with four mutually supporting squadrons in échelon bears strong elementary resemblance to that at Trafalgar in 1805. It was in dexterity and precision of detail far more than in principle that the difference lay. The first and the last great victory of the British navy had certainly more in common with each other than either had with Malaga or the First of June. In the zenith of their careers Nelson and Drake came very near to joining hands. Little wonder then if many of Nelson's captains failed to fathom the full depth of his profound idea. Naval officers in those days were left entirely without theoretical instruction on the higher lines of their profession, and Nelson, if we may judge by the style of his memoranda, can hardly have been a very lucid expositor. He thought they all understood what with pardonable pride he called the 'Nelson touch.' The most sagacious and best educated of them probably did, but there were clearly some—and Collingwood, as we shall see, was amongst them—who only grasped some of the complex principles which were combined in his brilliant conception.
An analysis of the memorandum will show how complex it was. In the first and foremost place there is a clear note of denunciation against the long established fallacy of the old order of battle in single line. Secondly, there is in its stead the reestablishment of the primitive system of mutually supporting squadrons in line ahead. Thirdly, there is the principle of throwing one squadron in superior force upon one end of the enemy's formation, and using the other squadrons to cover the attack or support it if need arose. Fourthly, there is the principle of concealment—that is, disposing the squadrons in such a manner that even after the real attack has been delivered the enemy cannot tell what the containing squadrons mean to do, and in consequence are forced to hold their parrying move in suspense. The memorandum also included the idea of concentration, and this is often spoken of as its conspicuous merit. But in the idea of concentration there was nothing new, even if we go back no further than Rodney. It was only the method of concentration, woven out of his four fundamental innovations, that was new. Moreover, as Nelson delivered the attack, he threw away the simple idea of concentration. For a suddenly conceived strategical object he deliberately exposed the heads of his columns to what with almost any other enemy would have been an overwhelming superiority. On the other hand, by making, as he did, a perpendicular instead of a parallel attack, as he had intended, he accentuated—it is true at enormous risk—the cardinal points of his design; that is, he departed still further from the old order of battle, and he still further concealed from the enemy what the real attack was to be, and after it was developed what the containing squadron was going to do. Concentration in fact was only the crude and ordinary raw material of a design of unmatched subtlety and invention.
The keynote of his conception, then, was his revolutionary substitution of the primitive Elizabethan and early seventeenth century method for the fetish of the single line. For some time it is true the established battle order had been blown upon from various quarters, but no one as yet had been able to devise any system convincing enough to dethrone it. It will be remembered that at least as early as 1759 an Additional Instruction had provided for a battle order in two lines, but it does not appear ever to have been used.[5] Rodney's manoeuvre again had foreshadowed the use of parts of the line independently for the purpose of concentration and containing. In 1782 Clerk of Eldin had privately printed his Essay, which contained suggestions for an attack from to-windward, with the line broken up into écheloned divisions in close resemblance to the disposition laid down in Nelson's memorandum. In 1790 this part of his work was published. Meanwhile an even more elaborate and well-reasoned assault on the whole principle of the single line had appeared in France. In 1787 the Vicomte de Grenier, a French flag officer, had produced his L'Art de la Guerre sur Mer, in which he boldly attacked the law laid down by De Grasse, that so long as men-of-war carried their main armament in broadside batteries there could never be any battle order but the single line ahead. In Grenier's view the English had already begun to discard it, and he insists that, in all the actions he had seen in the last two wars, the English, knowing the weakness of the single line, had almost always concentrated on part of it without regular order. The radical defects of the line he points out are: that it is easily thrown into disorder and easily broken, that it is inflexible, and too extended a formation to be readily controlled by signals. He then proceeds to lay down the principle on which a sound battle order should be framed, and the fundamental objects at which it should aim[6]. His postulates are thus stated:
'1. De rendre nulle une partie des forces de l'ennemi afin de réunir toutes les siennes contre celles qui l'on attaque, ou qui attaquent; et de vaincre ensuite le reste avec plus de facilité et de certitude.
'2. De ne présenter à l'ennemi aucune partie de son armée qui ne soit flanquée et où il ne pût combattre et vaincre s'il vouloit se porter sur les parties de cette armée reconnues faibles jusqu'à présent.'