The vastness of the issue decided by war, the fact that from its decision there is no appeal, the greatness of the forces that nations can produce, the length of experience of war extending through 8,000 wars, and during more than three thousand years of recorded history, the enormous literature of the subject, and the fact that more brain power, energy, and character have been devoted to war than to any other fruit of man's endeavor—combine to give to the conduct of war an importance that no other subject can possess.

The thing that each side brings forward against the other side is force; "that which moves or tends to move matter." In all ages, it has been directed primarily against the physical bodies of individual men, threatening each individual man with suffering and death. It appeals to the primal instinct of men, self-preservation, and is the ultima ratio regum, the last argument of kings—and not only of kings, but of all other living things as well.

The first feeling aroused by the threat against life, or physical well-being, is fear; and, therefore, the first force with which to oppose the threat is a force of the same spiritual nature as fear, but opposite in direction. This force is called in the English language "courage." Without courage every man and every nation would be at the mercy of every man or nation that made a threat against it. The inherent necessity for courage is thus apparent; and the reason is therefore apparent, for the fact that in every nation and tribe physical courage has been esteemed the greatest virtue in a man. In Latin, we know, the word virtus meant courage, and also virtue—showing that the Romans held the two qualities to be identical or similar.

In discussing the operations of war, little is usually said of courage. The reason, however, is not that its value is unrecognized, but that its existence is assumed; in the same way as that in which all the other faculties among the men are assumed, such as physical health, ability to march, etc. Movements to inspire fear, however, actions to break down the morale, are of frequent use; because, if the morale of the opposing side is broken down, its power of resistance is destroyed.

In the operations, therefore, of two contending parties, force is opposed by force. If the forces on both sides could be concentrated at a single point, and exerted in opposite directions, the result would be decided in an instant. Such an arrangement has never yet been brought about; though fairly close approximations have been made, when two parties have selected two champions who have fought for them—the victory going by agreement to the side whose champion became the victor.

Barring such rare occasions, contests in war have usually been between two forces spread over considerable areas of land or water; and the contest has usually been decided by the defeat of one of the two. If in any individual combat, all the forces possessed by both sides had been engaged, and if either force had been annihilated, the entire war between the two parties would have been decided. This was nearly the case in the naval battle off Tsushima between the Russian and Japanese fleets—and the treaty of peace was signed soon after. Usually, however, neither party to the quarrel has had all its forces on the field in any one battle, and neither force in the battle has been annihilated. Usually, only partial forces have been engaged, and only partial victories have been won; with the result that wars between contending nations have usually consisted of a series of battles, with intervals of rest between.

If two opposing forces in any battle were exactly equal in fighting power, neither side in any battle would gain a victory, the two sides would inflict identical amounts of damage on each other, and the two sides would end the battle still equal in force. At rare intervals, such conditions have been approximated; but usually one side has had more fighting power than the other, and has inflicted more damage of various kinds than it has received, with the result that it attained an advantage more or less important over the other, and with the further result that the original disproportion between the two forces was increased. The increase may not necessarily have been due to a greater number of killed and wounded or even to a greater loss of material, such as guns or ships; there may have been no increase in inequality in either of these ways, for the increase in inequality may have consisted in the fact that the weaker force was driven to a position less advantageous to it for conducting operations in the future. But whatever the nature of the advantage gained by the stronger side, the result has been that the weaker side has come out of the battle relatively weaker than it was before.

For this reason, it is highly desirable to each side to win each battle. This does not mean that the loss of any one battle by either party to a war means that the party losing that battle will necessarily lose the war; for many battles may be fought by such small portions of the whole nations' forces, or be lost by such small margins that the loss of one battle, or even several battles, may be retrieved; in fact, in few wars have the victories been all on one side. It does mean, however, that each lost battle is a backward step; and that for this reason the effort must be that no battle shall be lost.

Strategy and Tactics.—Now, to win battles, two things combine, strategy and tactics. The strategy of each side tries to arrange matters so that the forces on its side shall enter each battle with the greatest chance of victory; tactics tries to handle the forces with which it enters a battle in such a way that its side shall gain the victory. Strategy prepares for battles; tactics fights them.

The tactics of any battle must be in the hands of the commanders-in-chief on both sides. Any other arrangement is inconceivable; but the strategy controlling the series of battles in any war cannot now be committed to them solely; though it was usually committed to them until lately. In the days when Alexander went to war, or even when Napoleon and Nelson went to war, twenty-one centuries later, no telegraph by sea and land made swift communication possible; and the commanders on the spot were the only ones in possession of enough information about the contending forces to decide what measures should be taken. Even in those days, however, the capitals of the countries engaged in war, by reason of their knowledge of what was passing in the way of policy, exerted an influence on the strategy of the forces on both sea and land; Cæsar, for instance, was embarrassed in many of his operations by the Roman Senate, and it was for this reason that he crossed the Rubicon and passed from Gaul into Italy. When William I and Napoleon III went to war in 1870, however, Von Moltke had foreseen the effects of the telegraph and of rapid-mail communications, in giving to the headquarters of the army information of a much greater scope and reliability than had previously been the case, and had established a General Staff which had elaborated plans whereby not only would the commanders-in-chief in the field have the assistance of information compiled at headquarters, but whereby the general nature of the operations of a war, especially those operations at the outset on which the future conduct of the war would largely depend, would be decided and laid down in advance and during times of peace. The reason for the rapid victory of the Prussians over the French in 1870 was that the Prussians were better prepared in almost every way; especially in the most important thing—the war plans.