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.