Above all things we must distinguish thick tangled and impassable forests from extensive woods under a certain degree of culture, which are partly quite clear, partly intersected by numerous roads.
Whenever the object is to form a defensive line, the latter should be left in rear or avoided as much as possible. The defensive requires more than the assailant to see clearly round him, partly because, as a rule, he is the weaker, partly because the natural advantages of his position cause him to develop his plans later than the assailant. If he should place a woody district before him he would be fighting like a blind man against one with his eyesight. If he should place himself in the middle of the wood then both would be blind, but that equality of condition is just what would not answer the natural requirements of the defender.
Such a wooded country can therefore not be brought into any favourable connection with the defensive except it is kept in rear of the defender’s army, so as to conceal from the enemy all that takes place behind that army, and at the same time to be available as an assistance to cover and facilitate the retreat.
At present we only speak of forests in level country, for where the decided mountain character enters into combination, its influence becomes predominant over tactical and strategic measures, and we have already treated of those subjects elsewhere.
But impassable forests, that is, such as can only be traversed on certain roads, afford advantages in an indirect defence similar to those which the defence derives from mountains for bringing on a battle under