The order of battle (acies) has always been in some sense a line, for a permanent and obvious reason. None but those who are in front can fight, and the natural desire is to encounter the enemy with as great strength as possible. What will be the depth of the formation must depend upon many considerations, among which the nature of the weapons of the period is the most obvious, though others, such as the training of the men and their national traditions, are far from unimportant. A body of men drawn up more than four deep could hardly however be called a line. Similarly the order of march (agmen) has always been the converse of the order of battle: four men abreast require a fairly wide road. It is not necessary that a whole army shall move by a single road, in modern times they do not. But until armies grew very large it was not needful that they should separate: until roads grew plentiful and maps were available it was not safe, unless where no collision with the enemy was possible.
The acies and agmen are then, in their simplest form, the same thing looked at from two different points of view. The thin line drawn up to face the enemy may be imagined turning to the right or left and marching off. Of course it is not meant to be implied that such, and such only, were actually the primitive methods. Just as a mechanical problem is solved by assuming the absence of friction, a condition which in fact can never be realised, and correcting the result afterwards on account of friction, so one may for the moment leave out of sight all subsidiary things, in order to bring out in its simplicity the fundamental idea of an order of battle. Historically, no doubt, by the time men had advanced far enough to comprehend the value of combining to form a line, they had attained also to diversity of weapons, which would tend at once to interfere with this bare simplicity. Every fresh change, especially the introduction of war-chariots or of horse-soldiers, would further complicate the acies. So too, as soon as an army carries anything with it, the simple idea of the agmen is encroached on. Nevertheless both acies and agmen are rooted, so to speak, in the nature of things: the former can be traced in every battle, the latter in every march.
Some of the departures from the principle of the line are rather apparent than real. A reserve is no exception, even when it becomes a whole second, or even third line: for the reserve ex hypothesi is not fighting: when it is wanted to fight it is brought up to the front, and ceases to be in reserve. Foot-soldiers standing on the defensive, especially as against horsemen, present the largest amount of front in the safest way by forming a closed figure, the ring of the Northmen and of the Scots, or the familiar square of modern infantry in the days before the rifle. Nevertheless modifications are liable to be introduced, so to speak, from both sides. The order of battle is deepened, with the idea of giving greater impetus to a charge, from the weight of men behind backing up the front ranks. Epaminondas, using this device unexpectedly at Leuctra, defeated the Spartans, whose superior discipline and physique made them invincible so long as both sides used the same formation. His success led to the adoption of the Macedonian phalanx, and the abandonment of the line for the time being, until the Romans reverted successfully to the natural order. The order of march, for a real journey, cannot well be modified, because roads do not allow it. But for short marches, over open ground, there was much to be gained by massing men more closely together. They could hear orders better, and could be moved in any direction with more ease and precision. Hence arose the column, which is strictly speaking a series of short lines ranged one behind the other, and which, as military evolutions were developed, became the natural formation for manœuvring, as distinguished from fighting. Then obvious convenience would suggest keeping the troops as long as possible in the more handy formation of columns, even on the field of battle. Until the actual shock was impending, it was better to leave them so formed that they could be readily moved if necessary to another part of the field. Until artillery became really effective, the risk of increased loss, from cannon-balls passing through a solid body, instead of a line, was not very serious. Until the bayonet was introduced, the necessity for pikemen and musketeers acting together would tend to make deep formations, which are columns without their mobility, a virtual necessity. Thus in more ways than one column came to be regarded as the ordinary formation, line as the exception. And generals were led by the real convenience of mobility and facility of command, perhaps also by other calculations, to make attacks in column, with or without the intention of extending into line after the enemy's front had been pierced.
No words are required to show that troops armed with the short-range musket and bayonet, fighting against opponents similarly armed, are more effective in proportion as their depth can be safely reduced. More men can fire on the enemy, fewer are liable to be hit by the hostile bullets. This holds good alike for attack and for defence, and is indeed so obvious that when one finds great masters of the art of war adopting the column as the formation for attack, one begins to look for some latent flaw in the reasoning. There is none however from the material point of view: the real or supposed advantage of the column is moral only. When a mass of men formed in a deep column advances to attack a line, the front ranks of the column have the (imaginary) support of the ranks behind them. The imagination of the line is meant to be impressed by the spectacle of the heavy mass about to impinge on it. Both notions are really baseless: the line has no assailants except the front ranks of the column, who not only are not helped by those behind, but become the targets for the concentrated fire of the line. But imagination is a very real force in war, as in other human affairs: the generals who have formed heavy columns for attack, need not be supposed to have made a gross blunder: they may have adopted the method best suited to the qualities and traditions of their men. All that can fairly be concluded is that the line is enormously more effective for those who can bear the strain. And England may be congratulated alike on having the requisite toughness of material, and on having had generals who knew how to utilise it.
From the beginning of English history, as the foregoing pages have shown, the English modes of fighting have always led to the adoption of a thin line. Harold's house-carls must have stood in a single rank. The archers of Crecy cannot have been in more than two. The dismounted men-at-arms were drawn up, we are told on one or two occasions, four deep: and seeing that they had to sustain the momentum of mailed horsemen charging, they could not well have had less. The bodily strength and toughness of the English race, perhaps their lack of imagination, qualified them to bear the shock of battle well: and the habit of victory engendered a confidence of superiority, which was doubtless arrogant, but was also calculated to realise the expectation. Thus the national qualities and traditions were favourable to the adoption in later ages of a thinner line than other nations saw their way to employ.
The evidence of the drill books seems to be clear that in England the fighting formation in the seventeenth century was three deep, that in the war of American independence the practice of skirmishing in two ranks began, and that in the Peninsula the formation in two ranks for all fighting was finally adopted. A thinner line still is to all intents and purposes impossible. Whether the adoption of this system was the carrying out in full of the fundamental theory of the line, namely that it is the mode in which the largest proportion of force can be brought to bear on the enemy at once, or was suggested by virtual necessity, it is hard to tell. Given two very unequal forces opposed to each other, it is obvious that the smaller can form an order of battle tolerably equal to the larger only by making its line very thin. It is also obvious that this can be done safely only if the men are not to be daunted by feeling the lack of support. These conditions existed, in extreme form, in the early English wars in India. The soldiers of Clive and Coote, whether English or sepoys, were infinitely superior in discipline and equipment, if not in courage, to their enemies, and they were outnumbered many times over. It is quite possible that the first impulse to the two-deep formation came from India. However this may be, it is certain that England, and England alone, adopted a century ago the line of two ranks only; it seems to be also the case that at a much earlier period it was the English practice to fight in line, while other nations made more use of the column. And it is certain too that England gained enormously by being able to do so. The whole Peninsular war forms a commentary on this text, with Waterloo for a crowning lesson.
CHAPTER XI
THE EIGHTEENTH CENTURY
The peace of Utrecht left England in the very front rank of European powers, bound by treaty obligations to maintain the settlement then made, and taught by many victories to assume that her intervention would be effective. Moreover a new influence tended in the same direction: her kings had through their Hanoverian dominions a personal interest in continental affairs, and naturally tried to obtain English support in Hanoverian quarrels. Naturally also France was permanently jealous of the power which had destroyed her dream of naval supremacy, and had played the leading part in humbling Louis XIV. Thus it was to be expected that England would be involved more or less in most European wars, and also that she would habitually have France as her antagonist. She had private troubles in addition, in the shape of the Jacobite rebellion of 1745 and the revolt of the American colonies. The former could hardly have taken place had England not been at war with France: the latter succeeded very largely because France and the other European opponents of England seized the opportunity to coalesce against her. France and England were in truth pitted against each other all the world over. In North America they began the rivalry of the eighteenth century on fairly equal terms, so far as that continent was concerned. But the naval and commercial superiority of Great Britain, which grew more and more pronounced as time passed, insured her ultimate triumph in America in spite of all that France could do; while nearer home England found her advantage in supporting with money and men the continental enemies of her rival.