text: Chapter 6
  Figure 6-4. Notional enemy offensive operation
  TYPES OF DEFENSIVE OPERATIONS
  6-186. There are three types of defensive operations. These operations have significantly different concepts
  and present different problems. Units consider each independently when planning and executing the defense.
  Although the names of these types convey the overall aim of a selected operation, most defenses at division
  and higher echelons combine elements of all three types. The types of defensive operations are—
  (cid:122) Area defense.
  (cid:122) Mobile defense.
  (cid:122) Retrograde.
  AREA DEFENSE
  6-187. An area defense is a type of defensive operation that concentrates on denying enemy forces access
  to designated terrain for a specific time rather than destroying the enemy outright (ADP 3-90). The variations
  of an area defense include defense of a linear obstacle, perimeter defense, and reverse slope defense. The
  purpose of an area defense is to retain the terrain where the bulk of the defending force positions itself in
  mutually supporting prepared positions. Units maintain their positions and control the terrain between these