For a proper evaluation of the types of fortifications described in this study, they must be thought of as being integrated into a deep zone of mutually supporting strongpoints, based on key terrain features and capable of all-around defense.
The depth of the zone of fortifications varies according to the depth of the useful beach terrain and its vulnerability to attack, and depends also on the limitations imposed by the length of the coast line which must be defended.
The Germans adhere to the principle of seacoast defense by concentration of the main fires on and beyond the beaches. This follows from the fact that an invasion from any expected direction must be seaborne, and that the attacking forces will be most vulnerable to defensive fires just before and during the attempted landing.
The German organization of defensive positions into strongpoints follows the
familiar "hedgehog" (Igel) principle of grouping complementary works, each work
contributing predetermined fire for the defense of its own ground and for covering the
dead spaces of neighboring positions. The strongpoints in turn are similarly arranged to
form a deep, irregular pattern of defenses commanding all critical terrain. Minefields,
wire, and other obstacles are freely used, both tactically and protectively. The complete
arrangement is designed to absorb penetration, and to wear down, restrict, and impede the
attack until the counterattack can be launched.