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Amphibious Ships

Amphibious warfare ships are uniquely designed to support assault from the sea against defended positions ashore. They include several types of vessels designed to execute specific missions during amphibious operations-many developed during during World War II for use in the island campaigns in the Pacific Ocean and the invasions in Europe.

Despite the fiscal constraints of the Depression, the number and variety of naval ships devoted to amphibious purposes gradually increased in the 1930s. As the threat of American involvement in the war also grew stronger, vastly increased funds were made available for the Navy, the country's "first line of defense," and specialized transport and cargo ships appeared. These were tested and modified and became an increasing factor in the FLEXs which took place every year from 1935 on , usually with practice landings at Culebra and Vieques Islands off Puerto Rico in the Atlantic Ocean, at San Clemente Island off the southern Californi a coast, and in the Hawaiian Islands .

World War II erupted in Europe in September 1939. By mid-1940 the Germans had defeated Poland, and turned their armies westward, conquering Norway, Denmark, Belgium, Holland, and forcing France to surrender. The surviving British army barely escaped from France through the port of Dunkirk. But even that summer the inimitable Winston Churchill, Prime Minister of Britain, directed the organization of offensive "commando" forces to raid the German-held continent, and the design and production of landing craft. The craft being developed in Britain were small-dubbed L.C.T. for Landing Craft, Tank - being intended for operations in the English Channel. Churchill gave directions for development of an "Atlantic L.C.T.;" a craft that could cross oceans to unload its cargo of tanks. This "ship" was soon renamed L.S.T.-for Landing Ship, Tank. During 1941, the British Navy rebuilt three medium-size oil tankers to carry tanks and unload them through bow doors onto beaches or ramps. Then, the British and U.S. navies began building specially designed LSTs. John Niedermair of the U.S. Navy's then-Bureau of Ships, in November 1941 sketched out an awkward-looking ship that proved the design for more than a thousand LSTs that would be built during the war for the allied navies.

Because of the distances involved in the Pacific compared to the cross-channel problems in Europe and the lack of availability of specialized landing ships, the principal U.S. amphibious ships in the Pacific were the attack transports (APA) and attack cargo ships (AKA). These ships were of merchant design and carried troops and cargo (including vehicles); their decks were loaded with small landing craft that were put into the water alongside and then loaded with men and equipment. The landing craft then assembled into formations and headed for the beach.

At Guadalcanal amphibious tractors-or LVTs for Landing Vehicles, Tracked-were used to carry supplies ashore after the first troops had landed. These versatile craft were especially important in later invasions because they could crawl over the coral reefs surrounding mid-Pacific atolls that would stop conventional landing craft away from the beach in exposed positions.

The amphibious campaign continued, up the Solomon island chain and then across the central Pacific. In the south central Pacific the U.S. Navy-Marine Corps team assaulted coral atolls such as Tarawa and Eniwetok to wrest them from the Japanese in savage battles. The amphibious tractors, generally referred to as "amtracs," carried Marines right over the reefs and up onto the beaches. Other LVTs were armed with, howitzers, making them in effect floating tanks to go in with the landing craft to provide close gunfire support. Later conventional landing craft would land tanks, heavy guns, and supplies.

The LVTs were carried to the atolls by the LSTs: ungainly, flat-bottomed, box-like ships whose bow doors opened to reveal a garage-like interior filled with tractors that would roll right out into the water. After the beaches were secure other LSTs would run right up to the shore to disgorge tanks and other vehicles. Each LST could carry 2,100 tons of cargo (including several tanks or LVTs1. The LSTs crossed the ocean at about nine knots, giving rise to the slang designation of Large Slow Target for LST. Still, they were the right ship for the job, slow and of light, unarmored construction, they were relatively vulnerable and 41 sunk during the war; but many others fought off attacks, survived damage, and still landed the troops and tanks.

More than a thousand LSTs were built in the United States, and about a hundred more in British and Canadian yards. Even these were not enough. During the war Churchill declared: "In this period in the war all the most strategic combinations of the Western Powers were restricted and distorted by the shortage of tank landing-craft for the transport, not so much of tanks, but of vehicles of all kinds. The letters LST are burnt in upon the minds of all those who dealt with military affairs in this period."

Soon a "half-sister" to the LST arrived, the 203-foot LSM or Landing Ship, Medium, which could carry only five tanks, bridging the gap between smaller landing craft and the 328-foot LSTs. There were a host of other "beaching" craft, among them Landing Craft, Infantry (LC1) which carried 200 or more troops for short distances. Some of these craft were armed with mortars (LCIM), rockets (LCIR), and additional guns (LCIG) to support landings; a few were fitted with additional radios and a control center to serve as flotilla flagships (LCFF) for landing craft. Similarly, some LSMs were armed with rockets for landing support; each LSMR could unleash a salvo of several hundred 5-inch rockets, equal for a few seconds to the hitting power of a cruiser. Going down the scale in size there were several types of smaller landing craft that were' carried on or in the larger amphibious ships.

Standing offshore were the larger APA and AKA ships, carrying the bulk of the assault troops and their equipment that was brought ashore in small landing craft. Two other non-beaching ships joined the fleet late in the war, the Landing Ship, Dock (LSD) and Landing Ship, Vehicles (LSV). The dock ship had a large "well" or "dock" that could be flooded to float out landing craft pre-loaded with equipment or amphibious tractors; the vehicle ship was a huge, floating garage that could carry and unload some LVTs. Finally, there were amphibious command ships (designated AGC). These ships contained extensive command and control facilities to permit the senior officers directing the amphibious landing to effectively direct all aspects of the amphibious assault, one of the most complex of military operations.

By the war's end the U.S. Navy had built almost 1,500 large amphibious ships (32B-foot LSTs and larger, an equal number of ships of the 203-foot LSM and 157-foot LCI designs, and some 100,000 smaller landing craft and amphibious tractors.

After World War II hundreds of these amphibious ships were scrapped or sunk; most of the remaining ships were put in "mothballs," to be preserved for the future. Only a few amphibs were retained in service. The development of the atomic bomb and other modern weapons made it unlikely, in the opinion of many military authorities, that amphibious landings would ever again be required.

During the 25 October, 1949, exercise across three west coast beaches at the Waianae-Pokai Bay region of Oahu, Hawaii, long-period waves surging up the steep beach face caused substantial landing craft casualties on two of the beaches. Many of the craft broached and were shoved onto the steep beach by the surging breakers. Of the 20 landing craft sent ashore in 3 "waves" in the first 15 minutes of the amphibious exercise, 7 retracted and 8 were lost, some filling with water and sand when the ramps were lowered. The exercise was quickly halted and five of the craft later salvaged. Because of the problems experienced moving personnel, equipment and supplies through the surf and over the beach, the Department of Defense began the development of helicopters and air cushion vehicles.

During the Korean War the U.S. Marine Corps conducted experiments in landing troops from ships by helicopters, a technique known as vertical envelopment. This permits the assaulting troops to strike at a wider area than might otherwise be possible because of beach conditions, and to overfly beachhead defenses. Although not employed in the Korean War, the value of the concept was obvious. The first combat use of vertical envelopment techniques was the landing of British Marines at Port Said during the Anglo-French invasion of Egypt in November 1956.

During the 1950s the U.S. Marines acquired large numbers of troop-carrying helicopters and the Navy modified several carriers to work with the Marines. These ships were fitted with troop accommodations and maintenance, control, and storage facilities for helicopters.

During the late 1950s it was obvious that the World War II-built amphibious ships were wearing out. New ships were required, especially ships that could operate helicopters for vertical assaults. The first of the new ships were the amphibious assault ships of the IWO JIMA class (designated LPH, indicating amphibious ships that carry personnel and helicopters). The LPH with a length of 592 feet and a displacement of 18,300 tons is slightly larger than a World War II escort or "jeep" carrier. Each LPH can carry 2,000 troops in relatively comfortable accommodations (with bunks only three high compared to the six-deep bunks of some older ships). About 20 to 25 helicopters can be carried by the LPH, operating from the broad flight deck and being stored and serviced on the lower hangar deck, which is connected to the flight deck by elevators. The helicopters can lift the Marines, their artillery, equipment, and small trucks.

The next of the new amphibs was the amphibious transport dock (LPD), a development from the World War II landing ship dock which carried landing craft or LVTs in a floodable well. In the new LPD the well is covered over to permit operation of up to six helicopters; in the forward section of the ship are storage spaces for vehicles and accommodations for some 900 troops. A few modern LSD-type ships also have been built in the late 1960s and early 1970s to provide an improved capability for transporting landing to the assault area.

During the Korean War and subsequent operations it was repeatedly demonstrated that despite the advances in helicopter technology, LST-type ships were still required to land heavy equipment such as tanks, artillery, trucks, and bulldozers over the beach. About two dozen LSTs of several designs were built in the 1950s. Then, in 1969, the Navy commissioned the first of the NEWPORT class. This LST is considerably larger than her war-built predecessors (522 feet long vice 328 feet for the older ships); more important, the new LST can steam at a sustained speed of 20 knots, double the World War II transit speeds. The shape of the hull required to achieve 20 knots would not permit the blunt bow and doors of earlier LSTs. Thus, the NEWPORT unloads tanks and other vehicles over a 112-foot ramp that is extended over her bow. A stern gate also is provided to unload amphibious tractors into the water or to load vehicles alongside a pier.

By the early 1970s the Navy had some 60 amphibious ships capable of sustaining speeds of 20 knots or more: 2 Amphibious Command Ships (LCC, formerly AGC) 6 Amphibious Assault Ships (LPH) 6 Amphibious Cargo Ships (LKA, formerly AKA) 2 Amphibious Transports (LPA, formerly APA) 12 Amphibious Transport Docks (LPD) 13 Dock Landing Ships (LSD) 20 Tank Landing Ships (LST) (A few older ships also remained in service)

These ships simultaneously could transport four Marine brigade/air group assault teams (about 12 rifle battalions plus combat support, air, and logistic elements). Normally amphibious task forces of five or six of these ships operate with the U.S. Seventh Fleet in the western Pacific, the Sixth Fleet in the Mediterranean, and periodically with the Ready Group in the Caribbean. Each task group has a reinforced battalion of some 2,000 Marines on board. The other amphibious ships are en route to or returning from overseas duty, are engaged in exercises, or are in the shipyard being overhauled.

The first amphibious ship, built in 1942, was the landing ship tank (LST) designed primarily for transporting tanks, bulldozers, road-building equipment, artillery, and general cargo. Although their mission remains the same, the current ships are larger and faster than earlier LSTs. They offload cargo by means of a ramp over their bows; a stern gate allows offloading amphibious vehicles directly into the water. Fully loaded, these ships displace 8636 metric tons, measure 159 m (522 ft) in length and 21 m (69 ft) in beam, attain a speed of 20 knots, have a ship's crew of 290, and carry 400 troops.

Amphibious command ships were designed to provide control facilities to commanders during major amphibious operations. A pair of very sophisticated amphibious command ships, the BLUE RIDGE and MOUNT WHITNEY, contain advanced command and control facilities for a Navy amphibious task force commander and a Marine landing force commander and their staffs. These ships displace 19,304 metric tons, are 189 m (620 ft) long, and are 25 m (82 ft) in beam. They have a speed of 23 knots and carry a crew of 740. Amphibious assault ships transport elements of the landing force ashore using conventional landing craft, air-cushion landing craft, short-takeoff aircraft, and helicopters in support of amphibious landings. They displace 40,640 metric tons, are 257 m (844 ft) long and 32 m (106 ft) in the beam, have crews of 935, and carry 1700 troops. Their speed is 20 knots.

Amphibious transport docks carry and land marines with their equipment by embarked landing craft or amphibious vehicles augmented by helicopters. They displace 17,272 metric tons, are 174 m (570 ft) long and 26 m (84 ft) wide, have a crew of 425, and carry 900 troops; they reach speeds of 21 knots. Dock landing ships transport and launch a variety of loaded amphibious craft and provide limited docking and repair services to small ships. They have a crew of 355 and they carry 800 troops. Amphibious cargo ships carry heavy equipment and supplies in support of amphibious operations. They displace 21,031 metric tons, are 175 m (575 ft) long and 25 m (82 ft) wide, have a speed of 20 knots and a crew of 365, and carry 226 troops.

The LHA/LHD Amphibious Assault Ship are primary landing ships, resembling small aircraft carriers, that are designed to put troops on hostile shores. Modern U.S. Navy amphibious assault ships are called upon to perform as primary landing ships for assault operations of Marine expeditionary units. These ships use Landing Craft Air Cushion (LCAC), conventional landing craft and helicopters to move Marine assault forces ashore. In a secondary role, using AV-8B Harrier aircraft and anti-submarine warfare helicopters, these ships perform sea control and limited power projection missions. Amphibious warships are uniquely designed to support assault from the sea against defended positions ashore. They must be able to sail in harm's way and provide a rapid built-up of combat power ashore in the face of opposition. The United States maintains the largest and most capable amphibious force in the world. The Wasp-class are the largest amphibious ships in the world. The lead ship, USS Wasp (LHD-1), was commissioned in July 1989 in Norfolk, Va. The Guam (LPH 9), the last of the Iwo Jima Class, was decommissioned 25 August 1998.

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Page last modified: 07-07-2011 12:38:32 ZULU