Let us first consider the _quartermaster's department_, which, from the character and diversity of its duties, the amount of its expenditures, and its influence upon military operations, may be ranked as among the most important. This department provides clothing, camp and garrison equipage, animals and transportation of all kinds, fuel, forage, straw, and stationery, an immense variety of the miscellaneous materials required by an army, and for a vast amount of miscellaneous expenditures. It is, in fact, the great business operator of a military organization. In an active army, the success of movements depends very much on its efficiency. Unless the troops are kept properly clothed, the animals and means of transportation maintained in good condition, and the immense trains moved with regularity and promptness, the best contrived plans will fail in their development and execution. The department, at the commencement of the war, had supplies in store only for the current uses of the regular army. When the volunteer forces were organized it became necessary to make hasty contracts and purchases to a large amount; but as even the best-informed members of the Government had no adequate prevision of the extent and duration of the war, and of the necessary arrangements for its demands, a considerable period elapsed before a sufficient quantity of the required materials could be accumulated. Those were the days of 'shoddy' cloth and spavined horses. The department, however, exhibited great administrative energy, under the direction of its able head, General M. C. Meigs, and has amply provided for the enormous demands upon it. Depots for the reception of supplies are established in the large cities, whence they are transferred as required to the great issuing depots near the active armies, and from them to the depots in the field. Thus, the main depots of the Army of the Potomac are at Washington and Alexandria--a field depot being established at its centre, when lying for any length of time in camp. Only current supplies are kept on hand at the latter, and no surplus is transported on the march, except the required amounts of subsistence and forage. A great deal is said in connection with military movements, of 'bases of operation.' These are the points in the rear of an army from which it receives supplies and reënforcements, and with which its communications must at all hazards be kept open, except it has means of transportation sufficient to render it independent of its depots for a considerable period, or unless the country traversed is able to afford subsistence for men and animals. When an army marches along a navigable river, its secondary base becomes movable, and it is less confined to the necessity of protecting its rear. In Virginia, however, the connection of the Army of the Potomac with Washington is imperative, and this fact explains the contracted sphere of the operations of that army.