The _staff_, it must be recollected, is to an army what the masons, carpenters, ironworkers, and upholsterers are to a building. As the latter are the agents for executing the designs of the architect, so the staff are the medium by which the commander of an army effects his purposes. Without competent staff officers in all the various grades of organization constituting an army, the most judicious plans of the ablest commander will entirely fail. If a campaign is to be made, the commanding general, having formed his general strategical plan, needs the advice of his chief of staff as to the condition of his troops, and his assistance in devising the details. His adjutant-general's office must contain full records of the numbers of the troops--effective and non-effective--armed and unarmed--sick and well--present and absent, with all reports and communications relative to the state of the army. His quartermaster must have been diligent to provide animals, wagons, clothing, tents, forage, and other supplies in his department; his commissary and ordnance officer, the same in relation to subsistence and munitions--all having made their arrangements to establish depots at the most accessible points on the proposed route of march. His chief of artillery must have bestowed proper attention to keeping the hundred batteries of the army in the most effective condition. His chief engineer must have informed himself of all the routes and the general topography of the country to be traversed; he must know at what points rivers can be best crossed, and where positions for battle can be best obtained; his pontoon trains and intrenching implements must be complete and ready for service; his maps prepared for distribution to subordinate commanders. His inspector must have seen that the orders for discipline and equipment have been complied with. His medical director must have procured a supply of hospital stores, and organized the ambulance and hospital departments. His provost marshal must have made adequate arrangements to prevent straggling, plundering, and other disorders. His aides must have informed themselves of the positions of the various commands, and become acquainted with the principal officers, so as to take orders through night and storm with unerring accuracy. They must be cool-headed, daring fellows, alert, and well posted, good riders, and have good horses under them.