This may be summed up as the principle of maintaining the original _Ordre de Bataille_. This expression, which originally meant the “battle array,” or order in which the Army was drawn up for battle, is sometimes used to denote the strategical array, or the composition and distribution of the various formations which make up the Army. The _Ordre de Bataille_ has no longer any reference to their relative positions on the battle ground, which necessarily change with the circumstances of each engagement. But this document is still indispensable for an army. No Orders can be drafted except by referring to it, and without it the direction and control of an army would be impossible. A knowledge of the _Ordre de Bataille_ of the enemy--that is, of the composition and distribution of the Subordinate Commands of his army--is obviously of the first importance in planning movements and combinations against him. It can generally be arrived at from a study of his peace organization and his railway facilities for concentration, corrected by any information procurable as to the position of his troops. This information may come from various sources, such as newspaper reports of the progress of his concentration, captured documents and letters, deserters, and spies. After an action, the insignia on the uniforms of dead, wounded, and prisoners, the lettering of captured guns, wagons, and baggage, give valuable hints as to the units engaged. It is open to question whether such information might not be withheld from the enemy. In the Manchurian War the Japanese carefully avoided helping the enemy by indicating units on uniforms, and instructed their men, when wounded or captured, to refrain from stating their Corps. They increased the strength of their Divisions, altered the number of Divisions composing each Army, and even formed an additional Army out of time-expired reserves, without the facts leaking out. This greatly hindered the Russians from estimating the Japanese strength in the different sections of the great battles. Napoleon made a practice of allotting larger numbers to the Army Corps and Divisions commanded by his best Generals, and this irregularity was increased by his constantly raising additional battalions and squadrons to meet special exigencies, and by incorporating foreign contingents in his armies. The result was, the French _Ordre de Bataille_ was so irregular as to make any _a priori_ calculation of strength on the part of his enemies of doubtful value. The difficulty consequently found by the historian in calculating the strengths, and following the movements, of the French Armies in the Napoleonic Wars is a measure of that which his enemy’s Staff must have met in arriving at a definite idea of the strength and disposition of the French Forces at any given moment.