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CHAPTER 5

AMPHIBIOUS OPERATIONS

INTRODUCTION

The four types of amphibious operations are amphibious assault, withdrawal, demonstration, and raid. Each has a specific purpose. The amphibious assault involves landing and establishing forces on a hostile shore. In an amphibious withdrawal, forces withdraw from a hostile shore in naval ships or craft. An amphibious demonstration is designed to deceive the enemy by a show of force that deludes him into action unfavorable to him. In a raid, forces land from the sea on a hostile shore intending to occupy it only temporarily its objective is to inflict loss or damage, secure information, create a diversion, or evacuate individuals and materiel.

The phases of an amphibious operation follow a well-defined pattern or sequence of events or activities. This chapter discusses the activities in the general sequence of planning, embarkation, rehearsal, movement to the objective area, and assault and capture of the objective area. Some of the phases overlap

This chapter also gives watercraft commanders and operators the basic guidance Army watercraft transport units need to participate in amphibious operations that support an Army or joint force. FMs 31-11 and 31-12 contain more detailed information on amphibious operations.

PLANNING PHASE

Planning, as a separate phase of an amphibious operation, is the period between the issuance of the initiating directive to embarkation. It is a continuous process that extends from the time the initiating directive is issued to the end of the operation.

Normally, Navy and Marine assault units conduct amphibious operations. Army amphibians and watercraft are used as floating platforms for on-call supply movement and for general unloading after the beachhead has been secured. Army amphibians and landing craft can be part of the assault force.

Planning for coordinated training with shore party elements and for operational employment begins when the initiating directive assigning a water transport unit to the joint amphibious task force is received. Immediate liaison is established between the water transport unit and the naval beach group to which it is attached. The shore party's mission is twofold: to clear the beaches so the assault elements can land and move across them, and to provide combat support and interim combat service support for the assault elements.

Plans must be flexible so that combat demands can be met. All commanders who furnish support for the assault must be prepared to alter their support plans to meet the changing needs of the landing force. The need to coordinate the detailed actions of all forces involved complicates planning for an amphibious operation. Consequently, planning must be concurrent, parallel, and detailed. In addition to a primary plan, alternate plans must be developed.

During the planning phase, training shortfalls may be discovered. They may require extensive individual training as well as training with other elements of the amphibious task force. As plans are developed, appropriate personnel must be adequately briefed on the overall plans and their individual and collective responsibilities.

EMBARKATION PHASE

During the embarkation phase, the landing forces assigned to the amphibious task force, with their equipment and supplies, are assembled and loaded in assigned shipping sequence. This sequence is designed to support the landing plan and the scheme of maneuver ashore. Before the assault shipping arrives, water transport unit commanders, troop commanders, naval commanders, and shore party commanders prepare detailed embarkation and landing plans. FM 20-12 details embarkation planning.

Lighterage is moved to the amphibious objective area aboard landing ships or assault ships. The type and numbers of lighters that each ship of the transport group carries are identified by hull number. Representatives of the landing force coordinate with the appropriate naval transport echelon to determine them.

The senior water transport unit representative on each ship, the commanding officer of troops, and the ship's combat cargo officer arrange the following:

  • Billet assignments.

  • Assignment of crews, relief crews, and maintenance teams.

  • Assignment of working parties.

  • Storage for fuel, lubricants, and maintenance material. Items must be available en route and during initial stages of the assault.

  • Security details.

  • Messing procedures.

  • Stowage of weapons and ammunition.

Supplies and equipment must be prepared for loading before the assault shipping arrives in the embarkation area. Lighters should be completely serviced, fuel and water cans filled, accessories placed, and radio and navigation equipment waterproofed. A final inspection ensures all craft and equipment are in proper condition, securely lashed, adequately protected, and ready for the operation.

If ships are to be loaded offshore, the embarkation area should be organized so that amphibians use different beach areas. Lighters to be embarked aboard the same ship are marshaled together and escorted by naval guide boats to their assigned craft. Craft are loaded aboard assault shipping so that debarkation in the amphibious objective area is in the proper order.

REHEARSAL PHASE

The rehearsal phase of an amphibious operation is the period where elements of the task force, or the task force in its entirety, conduct one or more exercises under conditions similar to those expected at the beachhead. The purpose of the rehearsal is to test the adequacy of plans and communications, the timing of detailed operations, and the combat readiness of participating forces. It ensures all echelons are familiar with the plan. The three types of exercises are--

  • Separate force rehearsals. Elements whose tasks are not closely associated with those of the main body of the amphibious task force normally conduct separate rehearsals. The advance force and the demonstration force are examples of elements that conduct separate rehearsals.

  • Staff rehearsals. All staffs scheduled to participate in the operation conduct staff rehearsals. Conducted before integrated rehearsals, they usually take the form of command post or game board exercises. If possible, these exercises test communications facilities.

  • Integrated rehearsals. The rehearsal phase should include at least two integrated rehearsals for the assault phase. The first rehearsal omits actual bombardment and unloading supplies but stresses communications and control in executing ship-to- shore movement. The final rehearsal uses the actual operations plans. It includes token naval gunfire, air support with live ammunition, extensive troop participation and sufficient unloading to adequately test tactical and logistical plans, operation of ship-to-shore movement control organization, and the functioning of the shore party.

MOVEMENT PHASE

The fourth phase of an amphibious operation is the movement of the task force to the amphibious area. This includes the departure of ships from loading points, the passage at sea, and the approach to and arrival in assigned positions in the objective area. The task force is divided into movement groups which proceed on prescribed routes. Alternate routes are designated for emergency use. Movement groups are organized based on the speed of the ships involved and the time they are needed in the objective area.

Some movement groups are scheduled to arrive in the objective area before D-day; some, on D-day; and others, after D-day.

Movement groups that arrive before D-day are the advance force. If surprise is essential, such a force may not be used. The advance force prepares the objective area for assault. It conducts reconnaissance, minesweeping, preliminary bombardment, underwater demolitions, and air operations.

Movement groups arriving on D-day are the main body of the task force. They consist of one or more transport groups, landing ship groups, support groups, or carrier groups. Movement groups that arrive after D-day provide resupply after the initial assault. These massive operations involve moving materiels and personnel into the theater of operations to sustain the combat effort.

Movement groups that arrive after D-day provide resupply after the initial assault. These massive operations involve moving materiels and personnel into the theater to sustain the combat effort.

ASSAULT PHASE

The assault phase of the amphibious operations begins when the assault elements of the main body arrive at their assigned position in the objective area. It ends when the task force mission is accomplished. When the assault phase ends, the amphibious operation ends. Then the amphibious task force is dissolved as an organization, and its elements are reassigned. Responsibility for further operations in the former amphibious objective area is transferred.

The assault phase includes a sequence of six activities or operations:

  • The assault area is subjected to naval gunfire missile fire, and air bombardment.

  • Helicopters, landing ships and crafts, and amphibians move the landing force.

  • Assault elements of the landing force land in drop and landing zones and on the beaches.

  • Waterborne, helicopter-borne, air-dropped, and air-landed forces unite and seize the beachhead.

  • Naval forces provide logistic, air, and naval gunfire support throughout the assault.

  • Remaining landing force elements go ashore to conduct any operations required to support the mission.

The organization of landing ships, landing craft, and amphibious vehicles employed in assault landings parallels the landing force organization. The landing force is organized into a landing team. The naval organization has boat groups, waves, and flotillas.

Landing teams consist of an infantry battalion or similar level combat unit reinforced with combat support and combat service support units. The teams, normally waterborne or helicopter-borne, are organized into waves that contain troops and equipment that land at the same time.

Boat groups are the naval force's basic task organization for controlling amphibian vehicles and landing craft afloat. One boat group is organized for each battalion landing team or its equivalent. The boat group lands in the first wave of landing craft or amphibians.

Boat waves are the landing craft or amphibians within a boat group that carry troops to be landed at the same time. Organizing into waves helps control the boat group; command is through wave commanders rather than directly with individual boat commanders. Boat waves operate as a unit. The boat group lands in successive waves according to the assault schedule. The waves are numbered first wave, second wave, and so forth. Landing ships used to land battalion landing teams are organized as waves but are not included in an assault group.

Boat flotillas are formed when the operation of two or more boat groups require a common commander.

Ship-to-shore movement begins when ordered by the amphibious task force commander and ends when the unloading is complete. It may be divided into two periods: the assault and initial unloading period, and the general unloading period. The first period is tactical, and the second period is logistical. For ship-to-shore movement, tactical units are divided into special groupings and landed in successive waves. These waves are designated as scheduled, on-call, or nonscheduled units. Following the tactical units, supplies are landed at the discretion of the appropriate troop commander or as required by the landing force. Supplies so landed are designated as floating dumps or landing force supplies.

Scheduled waves normally consist of elements of the assault landing team, although other units may be included. Units included in scheduled waves are needed for the initial assault. The time and place for them to land are predetermined.

On-call waves are also needed in the initial assault, but they have no fixed time and place for landing. On-call boat waves are held in readiness in landing craft, ships, or amphibious vehicles near the primary assistant central control or approach lane control ships. On-call waves are landed when the landing force commander calls for them.

Nonscheduled units are directed to land when the need for them ashore can be predicted with reasonable accuracy. They are held in readiness for landing during the initial unloading period but are not included in either scheduled or on-call waves.

Floating dumps provide emergency supplies. They are preloaded in landing craft, landing ships, or amphibian vehicles to meet anticipated supply requirements. They remain near the line of departure and land when requested by the appropriate troop commander.

Landing force supplies are the supplies that remain in assault shipping after initial combat supplies and floating dumps have been unloaded.

Army watercraft do not normally land with the initial assault waves. They usually serve as floating dumps or on-call elements or deliver landing force supplies. Following landing of the initial waves, Army watercraft are stationed at designated control points until dispatched ashore by the naval control officer. When dispatched ashore, the crafts move to the designated beach for unloading. After unloading, they move to assigned assembly areas until routed to a specific ship for reloading. Army watercraft continue to function in this manner throughout ship-to-shore movement until released by the shore party commander. Then they revert to the control of their parent organization.

In amphibious operations, the commander of the amphibious task force via the naval control officer exercises control of ship-to-shore movement. The shore party via attached naval beach parties carries out near beach movement control. Water transport unit commanders remain waterborne until the general unloading period begins. Then they move ashore with their control elements to coordinate with the shore party commander and the staff of the terminal battalion (group) being phased ashore. When ashore, commanders establish company command posts and set up shore-based control systems. While waterborne, water transport commanders help the naval control officers dispatch and route craft and coordinate maintenance and supply activities for their units.

BEACH MARKERS

A system of beach markers is used while organizing the beach to receive landing crafts, landing ships, and amphibians. The markers help vessel operators locate the correct beach in daylight or darkness. Shore party personnel install the markers as soon as possible after the initial assault of an amphibious operation.

Beaches under attack are color designated, such as red beach or green beach, with markers of corresponding colors. The daylight markers are made of cloth and held aloft as shown in Figure 5-1. During daylight, a horizontal rectangle identifies the left flank of a beach, as seen from the sea; a square, the center of the beach; and a vertical cloth rectangle, the right flank. During night operations, a system of white and appropriately colored lights is used (Figure 5-l).

When the tactical plan dictates that a number of beaches be used, each colored beach may be further divided into beach number one, beach number two, and so forth. When the colored beaches are so divided, the markers are erected in pairs (Figure 5-l).

HYDROGRAPHIC MARKINGS

Hydrographic markings, such as those in Figure 5-2, have been developed for use near the shore in areas otherwise unsuitable for marking. The shore party commander determines the need for hydrographic markings and installs them. These markings have no relation to Coast Guard aids to navigation. (FMs 55-15 and 55-501 describe the navigational aids and the US buoyage system.) Figure 5-2 shows hydrographic markings for beach operations.

RANGE MARKERS

Range markers are two lights or markers located some distance apart and usually visible only from one direction. They are arranged in pairs in line with the center of the channel or the beach. When the operator positions his craft so that the range markers appear one over the other, the craft is on the axis of the channel or on the proper heading to arrive at a designated point on the beach. Characteristics or established ranges are indicated on the hydrographic charts for the particular area.

When ranges are constructed especially for beach operations, lighter operators get an explanation of their purpose and use in advance. Ranges should be used only after the charts or complete instructions from the water transport unit commander are carefully examined. It is particularly important to determine the distance that a range line can be safely followed. The shore party commander establishes ranges and installs range markers.

COMMUNICATIONS FOR AMPHIBIOUS OPERATIONS

The physical conditions in amphibious operations require almost complete dependence on radio communication during the initial landings and unloading periods. Because of the large number of radios available in landing force crafts and vehicles and with the combat elements, strict adherence to sound signal security practices is essential. Because of this complexity, wire communication should be established between shore installations as early as possible.

During the initial phases of the operations, the naval control system controls the lighters afloat and the shore party control system controls them ashore. Communication between elements of the water transport units and company headquarters is virtually nonexistent. However, the initial intracompany communications net must be ready to work as soon as the unit control system is established ashore. This net and the control procedures for its use must be provided for during the planning phase.

MAINTENANCE SUPPORT

During the actual conduct of an amphibious operation, only unit maintenance sections and direct support teams will provide floating craft maintenance support. Direct support and general support companies (Chapter 9) are not phased in until the situation ashore is completely established.

Every effort must be made to establish organizational and direct support maintenance personnel and equipment ashore as soon as practicable. Prompt delivery of supporting personnel and supplies prevents any serious impairment that an insufficient number of operational lighters may cause.



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