text: Fire Support in Depth During Large-Scale Combat Operations
  * Disrupt the enemy's tempo in the close area by attacking enemy forces preparing to attack.
  * Plan observation and fires to defeat or disrupt enemy attempts to breach friendly obstacles.
  * Plan obscurant fires to deny enemy observation or screen friendly movements between defensive
  positions.
  * Neutralize enemy threats in the rear areas.
  PREPARATION
  6-44. Preparation consists of those activities performed by units and Soldiers to improve their ability to
  execute an operation (ADP 5-0). Preparation creates condition that improve friendly forces' opportunities for
  success. Defending units prepare their AO before attacking enemy forces arrive, or they establish the defense
  behind a force performing a security operation. FS preparation consideration:
  * Actively participate in the joint and Army targeting processes.
  * Plan indirect fires in support of the barrier and obstacle plan.
  * Plan fires in support of patrols, convoys, or quick reaction forces.
  * Plan targets, observer positions (primary and alternate), triggers, and fires in support of all EAs
  for all phases of the defensive operation.
  * Recommend FSCMs to support each phase of the defensive operation.
  * Plan targets on avenues of approach to disrupt enemy attacks by striking the enemy on the
  approach and during their assault.
  * Ensure that forward positioned observers are resourced with adequate security, mobility, and
  situational understanding.
  * Prepare and harden artillery and TA positions.
  * Conduct rehearsals on the actual terrain.
  SECURITY
  6-45. Commanders secure their forces through the performance of security, protection, information
  collection, and cyberspace and EW operations. Security operations prevent enemy ISR assets from
  determining friendly locations, strengths, and weaknesses. FS must complement and support all security
  operations and unit protection plans by providing:
  * Support to security forces and actions in the consolidation and support areas.
  * Execution of deception fires and support to deception operations.
  * Disruption to enemy attacks.
  * Counterfire throughout the depth of the AO.
  * Suppress and obscure enemy overwatch positions.
  * Support friendly strong points.
  TYPES OF DEFENSIVE OPERATIONS
  6-46. There are three basic defensive operations- area defense, mobile defense, and retrograde. These apply
  to both the tactical and operational levels of war, although the mobile defense is more often associated with
  the operational level. The three operations are significantly different concepts and pose significantly different
  challenges in FS and FA planning and execution. Although the names of these defensive operations convey
  the overall aim of a selected defense, each typically contains static and mobile elements.
  AREA DEFENSE
  6-47. The 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 focus of the
  area defense is on retaining terrain where the bulk of the defending force positions itself in mutually
  supporting prepared positions.