The first shock of the assailant is sustained by the detached works, and when he attempts to penetrate in the intervals, his flanks become exposed to a deadly cross fire.

These intervals also allow the assailed to act on the offensive, by charging the enemy at the opportune moment.

But with raw and militia forces it will be safer to resort to continuous lines.

If cavalry form any part of the defensive force, it will be absolutely necessary to leave intervals through which these troops may charge.
A vertical section of all intrenchments is of the same general form; the dimensions will, of course, vary with the nature of the soil, and the time and means employed in their construction.

The minimum dimensions that can be used with any considerable advantage are given in Fig.