An amphibious operation is both similar and different in many ways to both land, naval and air operations. At its basic such operations include phases of strategic planning and preparation, operational transit to the intended theatre of operations, pre-landing rehearsal and disembarkation, troop landings, beachhead consolidation and conducting inland ground and air operations. Historically, within these scope of these phases a vital part is of success was often based on the military logistics, naval gunfire and close air support. Another factor is the variety and quantity of specialised vehicles and equipment used by the landing force that are designed for the specific needs of this type of operation.
Amphibious operations can be classified as tactical or operational raids such as the Dieppe Raid, operational landings in support of a larger land strategy such as the Kerch–Eltigen Operation, and a strategic opening of a new Theatre of Operations, for example the Operation Avalanche.
The purpose of amphibious operations is always offensive, but limited by the plan and terrain.
Landings on islands less than 5,000 km2 (1,900 sq mi) in size are tactical, usually with the limited objectives of neutralising enemy defenders and obtaining a new base of operation. Such an operation may be prepared and planned in days or weeks, and would employ a naval Task force to land less than a division of troops.
The intent of operational landings is usually to exploit the shore as a vulnerability in the enemy’s overall position, forcing redeployment of forces, premature use of reserves, and aiding a larger allied offensive effort elsewhere. Such an operation requiring weeks to months of preparation and planning, would use multiple task forces, or even a naval fleet to land corps-size forces, including on large islands, for example Operation Chromite.
A strategic landing operation requires a major commitment of forces to invade a national territory in the archipelagic, e.g. the Battle of Leyte, or continental, e.g. Operation Neptune invasion. Such an operation may require multiple naval and air fleets to support the landings, and extensive intelligence gathering and planning of over a year.
Although most amphibious operations are thought of primarily as beach landings, they can take exploit available shore infrastructure to land troops directly into an urban environment if unopposed. In this case non-specialised ships can offload troops, vehicles and cargo using organic or facility wharf-side equipment. Tactical landings in the past have utilised small boats, small craft, small ships and civilian vessels converted for the mission to deliver troops to the water’s edge.
Preparation and planning
Preparation and planning the naval landing operation requires the assembly of vessels with sufficient capacity to lift necessary troops employing combat loading. The military intelligence services produce a briefing on the expected opponent which guides the organisation and equipping of the embarked force. First specially designed landing craft were used for the Gallipoli landings, and armoured tracked vehicles were also available for the Guadalcanal Campaign. Helicopters were first used to support beach landings during Operation Musketeer. Hovercraft have been in use for naval landings by military forces since the 1960s.