The Prussian army in 1866 consisted of nine army corps. The German army to-day has twenty, and in case of war the number would be increased. Large forces like these are rendered manageable by grouping them into armies of four or five corps, and dealing with the armies as units. It is evident that the working of the armies and therefore of the whole depends upon the ease and certainty with which the several corps are directed. Some of the means taken to secure this end have been already touched upon. In the first place each of the component parts of the corps must be perfectly trained and disciplined. Secondly, the corps must have had so much practice in working together as a whole that it has none of the weaknesses of a "scratch team." Thirdly, the general must be a real commander, able to read a battle-field, to judge a situation coolly, and to decide promptly. These qualities are secured partly by the selection[1] exercised in the appointment of generals, partly by the frequent opportunities for practice and testing afforded by the manoeuvres. But it is not enough to secure a general of tactical and strategical ability and experience. He must be protected against the danger of being absorbed by the worries of administration. Before a body of 30,000 men can be assembled on the ground selected for manoeuvres or on the field of battle, a vast amount of business must be transacted, requiring for its performance abilities of quite another sort than those needed to handle and lead the troops in action. The men must all be clothed and equipped. They must be properly and regularly fed. The task of supplying an army corps with provisions is like that of feeding a small town which, instead of remaining in its place, moves every day to a new site ten or fifteen miles distant from the old one. Among 30,000 men there will always be a number of sick who require attention. If the corps should meet the enemy there may be thousands of wounded to be tended, removed, protected, and fed. Order must be maintained, so that a special set of functionaries is needed to apply and enforce the laws by which the army is regulated. The numbers of the corps can be maintained only by a constant stream of fresh men, trained soldiers not before employed in the war, arriving from its peace quarters. Every one of these matters needs constant attention, or the whole machine would get out of gear and cease to work. The friction that inevitably arises from these complicated necessities is diminished and to some extent overcome by the organization of responsibility among the several bodies composing the army corps. But the anxieties of the commanding general can never be removed. In order to realize the magnitude and variety of his cares, the attempt may be made to draw a rough picture of the army corps at work during a campaign.