text: Mobility
  crossing of a larger or similar size element; however, it is planned and conducted as a separate mission. If
  conducted as a mission that does not involve crossing additional elements, planning and consideration should
  be given to the recovery of the crossing assets. If the crossing is a precursor to a larger, follow-on crossing,
  recovery of the crossing assets may be accomplished as part of that follow-on task. If the covert gap crossing
  is being used as a precursor to a deliberate crossing and is detected by the enemy, the higher headquarters
  may need to reevaluate other potential crossing sites before conducting the deliberate crossing. A contingency
  plan must always be included in the planning of covert missions in the event that the mission is compromised.
  A covert crossing should not be confused with the assault phase of a deliberate gap crossing.
  Gap Fundamentals
  18-62. Successful gap crossing is characterized by applying gap-crossing fundamentals. These
  fundamentals are applied when a gap is encountered in the operational area. These fundamentals are—
  * Surprise.
  * Extensive preparation (less for hasty crossing).
  * Flexible planning.
  * Traffic management.
  * Organization.
  * Speed.
  See ATP 3-90.4/MCTP 3-34A for more information on gap fundamentals.
  Task Organization for Gap Crossing
  18-63. Units use the same organic command and control nodes for gap crossings as they do for other
  missions. These nodes, however, take on additional functions in deliberate gap crossings. For this reason,
  commanders specify which nodes and staff positions have specific planning and control duties for the
  crossing. Typically, units designate a crossing area commander, engineer, and headquarters to focus
  specifically on the efforts needed to cross the gap. Additional engineer units may also provide additional
  command and control nodes depending on the size and complexity of the gap crossing. This may require
  some temporary co-location of headquarters cells (or individual augmentation) and an increase in
  communication means. Units conducting a deliberate gap crossing organize into the following groups:
  * Assault force.
  * Assured mobility units.
  * Bridgehead force.
  * Breakout forces.
  Assault Force
  18-64. Assault forces seize the far side objective to eliminate direct fire on the crossing sites. Assault forces
  may cross by any means to include rubber pneumatic boats, air assault, or the use of civilian boats if available.
  The assault force may also be the unit that first secured terrain on the near side and identified if existing
  bridges were operational and where enemy forces are fighting or defending. The assault force normally
  crosses in waves, as sufficient boats are seldom available to carry the entire force across at once. It is a very
  complex operation, requiring synchronization, training and extensive rehearsals.
  Assured Mobility
  18-65. Mobility support forces (such as combat engineer companies, multi role bridge companies, and
  military police units) provide crossing means, traffic control, and other critical tasks supporting the crossing
  site. These supporting units are task-organized to perform specific tasks and are controlled using specified
  procedures that are clear, simple, and rehearsed by all elements to ensure responsive support of the plan and
  unity of command and effort.