Amphibious assault ship

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Six of the U.S. Navy's seven amphibious assault ships in formation

Amphibious assault ships, usually shortened to amphibs, phibs or popularly known as gator freighters, denotes a range of classes of warship employed to land and support ground forces on enemy territory by an amphibious assault. The largest fleet of these types is operated by the United States Navy. The heart of the American fleet are the ships of the Tarawa class, which dates back to the 1970s, and the newer and larger Wasp class ships that debuted in 1989.

Earlier ships which played a similar role to the current vessels as the heart of an amphibious assault included five Iwo Jima class landing platform helicopter vessels, built in the 1950s and 1960s and various converted fleet and escort carriers. The first of the type envisaged was the escort aircraft carrier USS Block Island (CVE-106/LPH-1), which never actually saw service as an amphib. Delays in the construction of the Iwo Jima class saw other conversions made as a stopgap measure; three Essex-class aircraft carriers and one Casablanca-class escort carrier were converted into amphibs, the Boxer and Thetis Bay classes.

The Tarawa and Wasp types and their Iwo Jima class forebears resemble aircraft carriers. However, the role of an amphibious assault ship is fundamentally different to that of an aircraft carrier. Its aviation facilities are not to support strike aircraft, but have the primary role of hosting helicopters to support forces ashore. However, the Wasp and Tarawa types do in fact carry a small number of Harrier jump jet attack planes. They also have a secondary role as "sea control ships", carrying more Harriers, something that was first used in combat during the 2003 invasion of Iraq.

Beyond the largest vessels in the fleet, a variety of other specialised types support amphibious assaults. These include the landing platform dock (LPD), landing ship dock (LSD) and command ships (LCC and AGF). Navies other than the USN operate still further types including the older landing ship tank (LST), landing ship logistics (LSL) and landing ship medium (LSM).

The history of the specialist amphibious assault vessel really begins during World War II. Prior to World War I, amphibious assaults had taken place using conventional boats. The disastrous Gallipoli landings of 1915 (see Battle of Gallipoli) showed that this type of operation was impossible in the face of modern weapons, especially the machine gun. The 1920s and 1930s did not see much progress in most of the world, the exception being the US Marine Corps. The small Corps operations of the period in central and south American lead to the development of amphibious assault doctrine much in advance of the rest of the world. By the late 1930s, concrete plans were beginning to form to build the first really specialised amphibious assault shipping.

Specialised shipping can be divided into two types, most crudely described as ships and craft. In general the ships carry the troops from the port of embarkation to the drop point for the assault and the craft carry the troops from the ship to the shore. Amphbious assaults taking place over short distances can also involve the shore-to-shore technique where landing craft go directly from the port of embarkation to the assault point.

Many of the early types of shipping were converted cargo vessels. However, the landing ship tank stands out. As the name suggests it is a specialised type for getting tanks ashore. Unlike the other larger shipping, LSTs could beach and discharge directly onto shore. Beyond the ships carrying the troops, other vessels were needed. It was quickly appreciated that amphbious assaults were such complicated operations that a specialised flagship was needed, with facilities that a normal naval vessel simply could not provide. It was also realised that battleships, cruisers and destroyers could not necessary provide all the fire support (including suppressive fire) that an assault would need. Therefore specialised shipping was developed that incorporated various direct and indirect fire weapons. These included guns and rockets. As part of the final barrage before an assault, the landing area would be plastered by these types.

Despite all the progress that was seen during WWII, there were still fundamental limitations in the types of coastline that were suitable for assault. Beaches had to be relatively free of obstacles, and have the right tidal conditions and the correct slope. However, the development of the helicopter changed the equation fundamentally.

The first use of helicopters in an amphibious assault came during the Anglo-French invasion of Egypt in 1956. Two British light fleet carriers were pressed into service to carry helicopters, and a battalion-sized airborne assault was made. The techniques were developed further by American forces in the Vietnam War and refined during training exercises. The modern amphibious assault can take place at virtually any point of the coast, making defending against them extremely difficult.

One of the most recent innovations is the LCAC or Landing Craft Air Cushioned. These large hovercraft further expand the range of conditions under which an amphibious assault can take place and increase the speed of transfer of assets from ship to shore.

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Bâtiment de Projection et de Commandement (BPC) Mistral, French Navy

It is often said that amphibious assaults are the hardest of all military operations to coordinate. They need such fine control and such a large degree of coordination that it is only the top tier powers that have the ability to even attempt them seriously, let alone pull them off. The two nations that have made by far the most amphibious assaults during the past century are the United States and United Kingdom. From the great assaults of WWII to the recent 400 mile amphibious assault on Afghanistan and the attack on the Al Faw peninsula in Iraq, both countries have been at the forefront of developing amphibious assault doctrine and shipping. The UK maintains what many would call the second most powerful amphibious assault fleet in the world.