text: Large-Scale Combat Operations
  distance degrades or disrupts single-channel VHF communications. Units should rehearse the single-channel
  communications plan for the area defense and mitigate any challenges before the enemy attacks.
  4-27. Signal nodes support each command post location and provide on-the-move wideband satellite
  communications to enable command and control on-the-move. Key command and control nodes should
  remain behind the main battle area, outside the range of cannon artillery. Units rehearse plans for battle
  handover and dislocation of command posts to mitigate the risk of the enemy locating and targeting friendly
  command and control nodes. Signal soldiers supporting command posts on the defense must train and
  rehearse command post displacement to reestablish communications as quickly as possible. The
  communications staff should work closely with the G-3 (S-3) when planning future command post locations
  to mitigate adverse effects of terrain and structures on the unit’s communications capabilities.
  4-28. If friendly communications nodes face imminent risk of being overrun, operators must evacuate
  COMSEC material and encryption devices or destroy them in place. Allowing COMSEC materials to fall
  into enemy hands compromises secure communications. COMSEC compromise disrupts all radio and data
  networks until operators and net control stations can conduct emergency cryptographic key supersession.
  Leaders must ensure all personnel train and rehearse these procedures as battle drills to prevent and mitigate
  COMSEC compromise.
  SIGNAL SUPPORT TO MOBILE DEFENSE
  4-29. A mobile defense is typically conducted when the terrain favors the attacker and there is sufficient
  depth to employ a striking force forward of the no penetration line (FM 3-0). The mobile defense consists of
  a fixing force, a striking force, and a reserve force.
  4-30. Signal support to an Army force conducting a mobile defense is similar to that for an area defense.
  However, command posts forward of the no penetration line will likely rely on mobile communications
  capabilities such as single-channel radios and wideband on-the-move capabilities. Command and control
  nodes behind the no penetration line have full DISN services, but must be prepared to displace to mitigate
  the risk of being located and attacked.
  4-31. Retransmission sites supporting the mobile defense should colocate with other Army elements if
  possible. If the retransmission site operates remotely, the site requires security augmentation. For
  retransmission planning considerations, see paragraph 4-15.
  SIGNAL SUPPORT TO RETROGRADE TASKS
  4-32. The retrograde is a defensive task that involves organized movement away from the enemy
  (ADP 3-90). Army units do not conduct the retrograde in isolation. Retrograde is part of a larger scheme of
  maneuver designed to regain the initiative and defeat the enemy. The three forms of retrograde are delay,
  withdrawal, and retirement.
  4-33. Retrograde operations are some of the most demanding ground combat operations and rely heavily on
  mobile communications support. Similar to the support during mobile defense, single-channel VHF radios
  are the primary communications capabilities to support a delaying, withdrawing, or retiring force. HF and
  narrowband (single-channel) satellite radios are alternate means of communications when terrain or distance
  challenge line of sight radio capabilities. Retransmission systems extend the range of single-channel radio
  networks to support command and control in retrograde operations. For retransmission planning
  considerations, see paragraph 4-15. The constant movement of the retrograde force requires multiple planned
  retransmission site locations with routes that support quick dislocation and reestablishment to support the
  maneuvering force. Retransmission teams must track the progress of the operation to maintain awareness of
  supported force locations and when the operation meets a trigger to move to the next location. Units
  conducting retrograde operations usually deploy command and control nodes to the support area to establish
  the main command post ahead of the retrograde force and a tactical command post maneuvering with the
  main body.