The local authorities and inhabitants oppose, instead of facilitating his operations; and if patriotism animate the defensive army to fight for the independence of its threatened country, the war may become long and bloody.

But if a political diversion be made in favor of the invading force, and its operations be attended with success, it strikes the enemy at the heart, paralyzes all his military energies, and deprives him of his military resources, thus promptly terminating the contest.

Regarded simply as the initiative of movements, the offensive is almost always the preferable one, as it enables the general to choose his lines for moving and concentrating his masses on the decisive point.
The first and most important rule in offensive war is, to keep your forces as much concentrated as possible.

This will not only prevent misfortune, but secure victory,--since, by its necessary operation, you possess the power of throwing your whole force upon any exposed point of your enemy's position.
To this general rule some writers have laid down the following exceptions:-- 1st.

When the food and forage of the neighborhood in which you act have been exhausted and destroyed, and your magazines are, from any cause, unable to supply the deficiency, one of two things must be done; either you must go to places where these articles abound, or you must draw from them your supplies by _detachments_.