On the Russian side regarded as not dangerous, it left national opinion greatly divided, and made the conduct of the war confused and languid; on the Japanese side apprehended as highly dangerous, it produced an enormous preponderance of pro-national opinion, and made the conduct of the war correspondingly vigorous. In the Franco-Prussian War of 1870–1871 a further point is illustrated. The essential factor in the stimulation of herd instinct by war is not the actual danger of a given war, but the apprehended danger of it. The Prussians were dangerous enough to France, but were not generally regarded as such by the French, and in consequence national {219} homogeneity did not develop as it did on a later occasion in face of the same menace. If pro-national and anti-national opinion, if belief and doubt in the justice of a given war, vary in relation to a single predominantly important psychological factor—the apprehended danger to the nation of the war in question—it is obvious that the ostensible and proclaimed grounds upon which such opinion is founded are less decisive than is commonly supposed. Finding, as we do, that the way in which a people responds to the outbreak of war depends certainly in the main and probably altogether on a condition not necessarily dependent on the causes of the war, it is obvious that the moral justifications which are usually regarded as so important in determining the people’s response are in fact comparatively insignificant. This conclusion agrees with the observed fact that no nation at war ever lacks the conviction that its cause is just. In the war of 1914–1918 each of the belligerents was animated by a passion of certainty that its participation was unavoidable and its purpose good and noble; each side defended its cause with arguments perfectly convincing and unanswerable to itself and wholly without effect on the enemy. Such passion, such certitude, such impenetrability were obviously products of something other than reason, and do not in themselves and directly give us any information as to the objective realities of the distribution of justice between the two sides. The sense of rectitude is in fact and manifestly a product of mere belligerency, and one which a nation at war may confidently expect to possess, no matter how nefarious its objects may ultimately appear to be in the eyes of general justice. The fact that such a sense of rectitude is a universal and inevitable accompaniment of war, and as strong in a predatory and {220} criminal belligerent as in a generally pacific one, gives us a convenient measure of the extent to which prejudice must prevail in warfare.[T]