other tolerably good roads running in a parallel direction, it is easy to see that, in regulating a march, there are no great difficulties which make rapidity and precision in the advance incompatible with the proper concentration of force. In a mountainous country parallel roads are both scarce, and the difficulties of communication between them great; but the defensive powers of a single column are very much greater.
In order to make this idea clearer let us look at it for a moment in a concrete form.
A division of 8,000 men, with its artillery and other carriages, takes up, as we know by experience in ordinary cases, a space of one league; if, therefore, two divisions march one after the other on the same road, the second arrives one hour after the first; but now, as said in the sixth chapter of the fourth book, a division of this strength is quite capable of maintaining a combat for several hours, even against a superior force, and, therefore, supposing the worst, that is, supposing the first had to commence a fight instantaneously, still the second division would not arrive too late. Further, within a league right and left of the road on which we march, in