The following maxims on subsistence have the sanction of the best military writers: 1st. Regular magazines should be formed, so far as practicable, for the supplies of an army; the levying of requisitions being resorted to only where the nature of the war, and the requisite rapidity of marches, render these absolutely necessary to success. 2d. Depots should be formed in places strengthened by nature or art, defended by small corps, or garrisons, and situated in positions least liable to attack. 3d. All great depots should be placed on navigable rivers, canals, railways, or practical roads, _communicating with the line of operations_, so that they may be transported with ease and rapidity, as the army advances on this line. 4th. An army should never be without a supply for ten or fifteen days, otherwise the best chances of war may be lost, and the army exposed to great inconveniences. Templehoff says that the great Frederick, in the campaign of 1757, always carried in the Prussian provision-train _bread_ for _six_, and _flour_ for _nine days_, and was therefore never at a loss for means to subsist his forces, in undertaking any sudden and decisive operation. The Roman soldier usually carried with him provisions for fifteen days. Napoleon says, "Experience has proved that an army ought to carry with it a month's provisions, ten days' food being carried by the men and baggage-horses and a supply for twenty days by the train of wagons; so that at least four hundred and eighty wagons would be required for an army of forty thousand men; two hundred and forty being regularly organized, and two hundred and forty being obtained by requisition. For this purpose there would be a battalion of three companies for the military stores of each division, each company having its establishment for forty wagons, twenty being furnished by the commissariat, and twenty obtained by requisition. This gives for each division one hundred and twenty wagons, and for each army, four hundred and eighty. Each battalion for a provision-train should have two hundred and ten men." 5th. An army, while actually in motion, can find temporary resources, unless in a sterile country, or one already ravaged by war, or at the season of the year when the old crops are nearly exhausted and the new ones not ready for harvest; but, even supposing the army may in this way be partially or wholly supplied, while in motion, it nevertheless frequently happens that it may remain for some days in position, (as the French at Austerlitz and Ulm;) a supply of hard bread for some ten days will therefore be important to subsist the army till a regular commissariat can be established.