text: The Defense
  8-104. During the preparatory phase of the defense, sustainment operators normally pre-position supply
  stocks, particularly ammunition and barrier materials, in the BPs of defending forces. They also establish
  maintenance and casualty collection points. Sustainment operators address these and other sustainment
  preparations in the planning process to avoid compromising the operation. Units can include sustainment
  preparations in their military deception plans.
  PROTECTION
  8-105. Unit survivability is critical to defensive success. Protection preserves subordinate unit capabilities
  so that units can use those capabilities to apply maximum combat power at the desired times and places.
  Criticality, vulnerability, and recoverability are some of the most significant considerations for units in
  determining protection priorities. They use available decision support tools and analyses to assess the unit’s
  critical assets and key vulnerabilities. Units plan and prepare for enemy attacks by predicting where the next
  attack will occur and applying measures to mitigate the attack. These enemy attacks may be from
  conventional, irregular, or terrorist forces and drive changes in local unit protection or individual protective
  measures. Incident management plans and environmental considerations integrate the protection tasks and
  their associated systems. The protection tasks discussed in paragraphs 8-106 through 8-133 have additional
  defense-specific planning considerations not addressed in Chapter 1. (See ADP 3-37 for more information
  on protection tasks.)
  Survivability
  8-106. Since an attacking enemy force usually has the initiative in terms of where and when it will attack,
  a defending unit takes many actions to protect the force from losses due to enemy actions. The survivability
  effort for the defense enables units to concentrate firepower from fixed positions. To avoid detection through
  the forms of contact and destruction by enemy forces, units move frequently and establish survivability
  positions quickly. To provide flexibility, units may need primary, alternate, supplementary, and sequential
  positions. This is particularly true of units defending key or decisive terrain. Units enhance their survivability
  by using concealment, military deception, dispersion, masking, and field fortifications. Units avoid
  predictable defensive preparations because enemy forces tend to attack lightly defended areas.
  8-107. When preparing area and mobile defenses, engineers supporting the defensive effort help maneuver
  and supporting units prepare fighting and survivability positions. Units locate these positions throughout the
  defending unit’s assigned areas from the security area, through the MBA, to the echelon support area. BCTs
  pass survivability requirements beyond the capabilities of their brigade engineer battalions to the current
  operations integrating cell in their higher echelon headquarters. That headquarters then tasks a maneuver
  enhancement brigade or functional engineer brigade to provide the required support based on the mission
  variables. These engineers also prepare any strongpoints required by the concept of operations.
  8-108. Survivability tasks include preparing and constructing trenches; command post shelters; and artillery
  firing, radar, and combat vehicle fighting positions. Units provide guidance on the level of protection—such
  as hull defilade or overhead cover, system priorities, and early use of specialized engineer systems that can
  construct survivability positions. Their priority in engineer survivability planning during defensive operations
  is determining the most appropriate locations and standards for the construction of survivability positions.
  This includes such things as determining overhead cover standards, such as capable of resisting penetration
  by 82mm mortar or 152mm howitzer shells.
  8-109. Units protect supplies against blast, shrapnel, incendiaries, and CBRN contamination. They can
  protect supplies loaded on tactical vehicles against almost anything but a direct hit by constructing berms
  large enough to accommodate vehicles and deep enough to keep supplies below ground level. These berms
  may not provide the desired degree of protection against an enemy force using indirect fire or cluster
  munitions. The echelon engineer officer can advise sustainment operators about storage area sites that reduce
  the requirements for engineer survivability support without reducing the degree of protection provided.
  8-110. The defending unit’s subordinate maneuver elements occupy their assigned areas as soon as possible.
  This allows those units to have as much time as possible to prepare their defensive positions and enhance the
  defensive characteristics of the terrain within those assigned areas. This includes the construction of fighting
  and survivability positions.