text: Chapter 18
  Bridgehead Force
  18-66. A bridgehead force is a force that assaults across a gap, after the crossing is established, to secure
  the enemy side (the bridgehead) to allow the buildup and passage of a breakout force during gap crossing
  (ATP 3-90.4/MCTP 3-34A). The bridgehead is an area on the enemy side of the linear obstacle that is large
  enough to accommodate the majority of the crossing force, has adequate terrain to permit defense of the
  crossing sites, provides security of crossing forces from enemy direct fire, and provides a base for continuing
  the attack (ATP 3-90.4/MCTP 3-34A). The bridgehead line is the limit of the objective area in the
  development of the bridgehead (ATP 3-90.4/MCTP 3-34A).
  Breakout Force
  18-67. Breakout forces attack to seize objectives beyond the bridgehead as a continuation of the offense.
  (See ATP 3-90.4/MCTP 3-34A for more information on gap organization.)
  Gap Crossing Planning
  18-68. The discussion on planning mobility applies to gap crossing in ATP 3-90.4/MCTP 3-34A; however,
  force allocation against enemy units has an added dimension of time that is affected by the crossing rate.
  Friendly forces can only arrive at the crossing site at the rate at which they can cross the gap. This rate will
  change at various times throughout the crossing. The rate at which combat forces need to cross will directly
  affect the number of crossing sites.
  18-69. A major control mechanism category is graphic control measures. The unit uses graphic control
  measures to delineate areas of responsibility for subordinates and to ease traffic control. (See ATP 3-90.4/
  MCTP 3-34A for more information on graphic control measures for a gap crossing.)
  Gap Crossing Execution
  18-70. A deliberate river crossing is costly in terms of manpower, equipment, and time. Generally, units
  conduct it against a well-organized defense when a hasty river crossing is not possible or when one has failed.
  A deliberate river crossing requires the concentration of combat power on a narrow front, capitalizing on the
  element of surprise.
  18-71. A division or corps deliberate river crossing is an operation conducted as part of an offensive
  operation. A division is normally the smallest organization that can conduct a deliberate wet-gap crossing. It
  is usually an implied task in a larger mission given by the corps. A gap crossing is usually not the final
  objective; however, units must quickly cross a river and rapidly secure the bridgehead line to support follow-
  on offensive action against the enemy. The enemy will normally use the gap as a tactical obstacle system to
  slow and gain positional advantage against the division advance. The intent of the division is to maintain its
  momentum through the crossing.
  18-72. A deliberate wet-gap crossing has six phases. They are distinct phases for planning, but there is no
  pause between them in execution. See table 18-3 for the phases.
  Table 18-3. Deliberate wet-gap crossing phases
  Phase Description
  Set the Conditions The planning and continued targeting operations in the deep, close, and
  support areas to defeat enemy forces deep as well as close to
  synchronize one or more gap crossing operations with all warfighting
  function capabilities in five domains against an adaptive enemy force.
  Advance to the gap The attack to seize objectives that secure the near side terrain, which
  offers favorable crossing sites and road networks and provides enough
  area to stage crossing forces while preventing congestion and an
  undesirable massing of assets.
  Assault across the gap The units assaulting across the gap to seize the far side objective,
  eliminating direct fire into the crossing sites.