text: Chapter 6
  * Covert crossing is a planned crossing of an inland water obstacle or other gap in which the crossing
  is intended to be undetected (ATP 3-90.4). The primary purpose of the covert crossing is to
  facilitate undetected infiltration of the far side of a gap. A covert crossing is normally conducted
  by BN and smaller forces. It is used when surprise is essential to infiltrate over a gap and when
  limited visibility and terrain present the opportunity to reduce or defeat the enemy obstacle (gap)
  without being seen. Through surprise, the commander conceals capabilities and intentions and
  creates the opportunity to position support and assault forces to strike the enemy unaware or
  unprepared.
  6-145. Commanders use the same organic C2 nodes for gap crossings as they do for other missions. These
  nodes, however, take on additional functions in deliberate gap crossings. This may require some temporary
  collocation of HQ cells and an increase in communication means. Commanders conducting a deliberate gap
  crossing organize their units into assault, assured mobility, bridgehead, and breakout forces discussed below:
  * Assault force seizes the far side objective to eliminate direct fire on the crossing sites.
  * Assured mobility forces such as combat engineer companies, mobility augmentation companies
  and mobility assault companies, bridge companies, military police, and CBRN units that provide
  crossing means, and traffic control.
  * Bridgehead force assaults across a gap to secure the enemy side (the bridgehead) to allow the
  buildup and passage of a breakout force during gap crossing.
  * Breakout force attacks to seize objectives beyond the bridgehead as a continuation of the offense.
  6-146. A successful gap crossing is characterized by applying gap-crossing fundamentals. These
  fundamentals are applied when a gap is encountered in the OA. These fundamentals are as follows:
  * Surprise.
  * Extensive preparation (less for hasty crossing).
  * Flexible planning.
  * Traffic management.
  * Organization.
  * Speed.
  6-147. FS Considerations for gap crossings are below:
  * Plan fires at depth to isolate the bridgehead area from enemy reinforcement.
  * Plan fires to soften enemy defense and crossing sites and to seal- off exit bank positions.
  * Establish CFZs on crossing sites and staging areas.
  * Make fires immediately available to crossing forces. If necessary, have GS artillery fire while DS
  artillery is crossing.
  * Assign priority of fires to assault forces.
  * Assign nonstandard missions to GS units. Change the priority of calls for fire, fire planning, and
  other inherent responsibilities as necessary.
  * Plan smoke and suppression fires in greater than normal amounts if necessary.
  * Use smoke to screen both actual and dummy crossing sites.
  * Use smoke to obscure enemy direct-fire positions in the bridgehead area until the crossing forces
  can engage them.
  * Suppress enemy forces in the bridgehead area until the assault force can provide its own
  suppressive fires.
  * Use all available TA assets to identify targets in the bridgehead area.
  * Have indirect-fire weapons cross the river with the forces they support.
  * Use CAS and attack aviation to expand the bridgehead.
  COUNTERMOBILITY
  6-148. Countermobility a set of combined arms activities that use or enhance the effects of natural and man-
  made obstacles to prevent the enemy freedom of movement and maneuver (ATP 3-90.8). The primary
  purposes of countermobility operations are to shape enemy movement and maneuver and to prevent the