text: Security Operations
  to the protected force. A commander may assign a guard operation to protect a stationary or moving force. There are
  three types of guard operations—
  * Advance guard.
  * Flank guard.
  * Rear guard.
  5-55. A Cavalry squadron, maneuver battalion, or BCT performs guard operations. A guard force operates
  within the range of the main body’s indirect fire weapons. A guard force accomplishes all the tasks of a
  screen, but then deploys over a narrower front to permit the concentration of combat power. Squadron-sized
  elements or higher generally conduct guard operations due to the protection and assets required. A BCT
  conducts guard for the division and corps.
  5-56. Staffs consider augmenting the guard force based on the anticipated threat and tasks for the guard force.
  Dependent on the BCT type, the guard force has different combat power capabilities than the parent force it
  protects. Additionally, BCT commanders consider and plan for the integration of assets and enablers across
  all warfighting functions.
  5-57. The guard force differs from a screen in that the guard force contains sufficient combat power to defeat,
  cause to withdraw, or fix lead threat elements before they can engage the protected force and forces the
  enemy main body to deploy early. A guard force is appropriate when contact is expected, there is an exposed
  flank or a threat to the rear, the protected force is conducting a retrograde operation, or there is a requirement
  for greater protection than a screen provides.
  5-58. Attack and reconnaissance aviation units supporting a guard operation accomplish all the tasks of a
  screen, zone reconnaissance, and hasty attack mission. Units place emphasis on the early development of the
  situation along the main body’s axis of advance. Early contact with the enemy may cause enemy forces to
  deploy prematurely providing opportunity to the main body to counterattack a vulnerable enemy force. Aerial
  assets support the guard force by screening between and in front of battle positions as they are established.
  Aviation reconnoiters the area between the guard or cover force and the main body, assists in maintaining
  contact between the security force and the main body, and protects the flank guard force to allow it to
  concentrate on its security or battle position tasks. When supporting a moving force, aviation units
  reconnoiter along the flanks of advancing ground units by conducting any type of reconnaissance to
  successive screen areas, observation posts, or battle positions.
  GUARD TASKS
  5-59. BCTs, maneuver battalions, and squadrons conduct the following guard tasks within capability:
  * Detect and report all enemy elements attempting to pass through the guard, both ground and aerial
  and provide the protected force commander early warning of enemy activities.
  * Conduct counterreconnaissance to destroy or defeat all enemy reconnaissance elements according
  to engagement criteria.
  * Maintain contact with the protected force and other forces operating on its flanks.
  * Maintain observation of avenues of approach that affect the protected forces missions.
  * Locate and identify the lead elements that indicate the enemy’s main attack, as prescribed in the
  enemy’s order of battle based upon the IPB (when facing an echeloned enemy force).
  * While displacing, determine the direction of enemy movement, maintain contact, and report
  threat activities.
  * While displacing, impede and harass the enemy to provide the protected force commander with
  additional time and maneuver space.
  * Cause the enemy main body to deploy prematurely.
  * Maintain contact with enemy forces and report activity in the assigned area.
  * Deny ground observation, and prevent direct fire contact on the protected forces.
  * Deny the enemy information about the size, strength, composition, and objective of the main body.