When the Cold War began, the American amphibious fleet consisted entirely of ships built for World War II. The vast majority of these were just six or seven years old at the beginning of the Korean War and, at the time, represent the most capable amphibious warfare ships ever devised. Despite the massive post-war drawdown, the fleet of 1950 still consisted of 154 ships, including 29 attack transports (APA), 30 attack cargo ships (AKA), 18 landing ships dock (LSD), and 77 landing ships tank (LST), as well as numerous smaller craft.
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| USS Haskell (AKA-117) - note the large number of landing craft on davits and alongside |
In this force each type of ship performed a specific task. The APA’s carried the soldiers and their equipment as well as small landing craft to put them ashore. They were a somewhat eclectic mix of ships from five different class, the most numerous of which were the eighteen members of the
Haskell-class. These were modified Victory ships, 139 meters in length and capable of 16 knots. They carried 1565 soldiers and 123,000 cubic feet of cargo. As these were deep draft ships that were loaded and unloaded by crane, they landed their passengers and cargo using a variety of landing craft that were carried on the main deck. These craft consisted of two 17 meter LCM (Landing Craft, Mechanized) for heavy equipment, twenty two 11 meter LCVP (Landing Craft, Vehicle, Personnel) for infantry and light equipment, and two LCPL (Landing Craft, Personnel, Large) or LCPR (Landing Craft, Personnel, Ramp) for miscellaneous duties. These craft would be lowered into the water by 35 ton cranes and soldiers would then climb down their transport’s sides on nets to reach their boats, while equipment would be hoisted down. Such a process was slow, dangerous, and could only be done in good weather.
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| The Andromeda-class ship Centaurus (AKA-17) |
The AKA’s carried the bulk of the cargo needed for the operation as well as their own small landing craft. Of the three classes of AKA, the most common were the twenty two
Andromeda-class ships. Like the
Haskell-class, these were modified Victory ships. Unlike the
Haskell-class, they only had accommodations for a small number of troops and instead carried 323,500 cubic feet of dry cargo - a substantial fraction of which was refrigerated storage. The embarked landing craft were likewise oriented more towards moving cargo than people and consisted of six 17 meter LCM(6), two 15 meter LCM(3) fourteen LCVP, and two LCPL or LCPR.
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| LST-1141 (later USS Stone County) landing equipment in Korea |
Moving heavy equipment was the duty of the LST, as it was far simpler to land vehicles directly on to the beach via these ships' large bow doors. In 1950, there were three main classes of LST (LST-1, LST-491, and LST-542 - LST's were not given names). However, these represented only minor variations on the same basic hull. All were 100 meters long and capable of 12 knots. They accommodated 141 troops and 9,772 square feet of cargo (cubic feet is commonly given for bulk cargo while square feet is given for vehicles). In addition to the bow doors, they were usually equipped with up to four LCVP or LCPR. These landing craft were important since even with its flat bottom an LST could only beach in suitable spots and when carrying a fraction of its maximum ocean going load. The LST’s were also responsible for launching the LVT (landing vehicle tracked) - the predecessor to today’s AAV-7. This was done by opening the bow doors while still a distance offshore and letting the LVT’s drive out into the water. There was also a pair of slightly larger LST-1153 that commissioned in the late 1940's. Although these were the same length as the preceding classes, they had a 2 meter wider beam, giving them space for 197 troops and 14,340 square feet of cargo. Further, they had steam turbines rather than diesels and could reach 14 knots.
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| Ashland (LSD-1) in her original configuration with an exposed well deck, by Korea this would have been partially covered with by a semipermanent deck |
The last class of amphibious ship was the LSD, which was designed to move large landing craft over open seas. In 1950, there were two classes of LSD - the
Ashland-class and
Casa Grande-class. However they shared the same hull. Both were 140m, had a design speed of 17 knots, and dedicated nearly their entire length (over 120 meters) to a floodable wet-well deck similar to those found on nearly all amphibious ships today. But unlike modern amphibious ships, this well deck was not seen as a way to unload the LSD, but as a way to transport fully loaded large landing craft that were too small for ocean crossings. This meant that the LSD's were built with surprisingly little space for troops or equipment - they could only accomodate 226 troops and 17,316 square feet of cargo, just slightly more than the large LST's. However, the well deck could fit two 57 meter LCT (landing craft tank), three 36 meter LCT, or fourteen LCM. After this cargo had been launched, the LSD would then serve as a floating repair facility to maintain the entire amphibious force’s landing craft.
Together, these four types of amphibious ship performed admirably in Korea, conducting several successful amphibious assaults as well as amphibious withdrawals in the face of advancing Chinese forces. The amphibious fleet also performed crucial secondary tasks such as ferrying men and supplies to the Korean peninsula and supporting minesweeping efforts. Over the course of the fighting many reserve ships were recommissioned and by 1953, the amphibious fleet had grown nearly 60% to 243 ships and included 40 APA, 36 AKA, 21 LSD, and 146 LST. The war also caused a new generation of amphibious ships to be laid down, although they arrived too late to participate. This new generation followed the same basic structure as the World War II fleet, and included an APA, AKA, LSD, and LST. The difference was that the new classes were all larger, more capable, and significantly faster than their predecessors.
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| LST-1157 (later USS Terrell County) - note the much larger superstructure than proceeding classes. |
The first of these new ships were the fifteen LST-1156, which began joining the fleet in 1953. At 117 meters and 14 knots, the new LST could carry 395 troops and 16,500 square feet of cargo. In 1954, the first of eight
Thomaston-class LSD's joined the fleet. These were 155 meter, 20 knots ships that could accomodate 353 troops and 19,800 square feet of cargo. Their 20 knot speed would become the standard for all large amphibious ships for the next decades. This growing speed difference between the LST's and the other amphibious ships was addressed by the 17 knot
De Soto County-class LST of 1957 (all LST's received names in 1955). But higher speed was not the only improvement of this seven ship class, as they could accomodate 636 troops and 18,313 square feet of cargo - roughly twice the capacity of a World War II LST.
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| USS Thomaston (LSD-28) |
However, the accompanying APA and AKA classes were less successful. The latter, USS
Tulare (AKA-112), joined the fleet first in 1956. She was a modified
Mariner-class cargo ship, with a length of 172 meters, a speed of 20 knots, and
could accomodate 319 troops and 450,000 cubic feet of cargo. Landing craft consisted of nine LCM, fourteen LCVP, and three LCPL, all serviced by 60 ton cranes that could lift the new M46 and M47 tanks. However, despite these impressive statistics,
Tulare would be the only ship of her class. The
Paul Revere-class APA, which was also based on the
Mariner-class, was similarly cut short with just two members joining the fleet in 1958 and 1961.
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| USS Tulare (AKA-112) - note the much heavier masts and the helipad aft |
The reduction in the number of new ships was accompanied by a post-war drawdown that began in 1955, when 34 ships were decommissioned. The fleet continued to decline until 1960, when it reached its nadir of 151 ships, including 21 APA, 14 AKA, 3 LPH, 27 LSD, and 92 LST. However, things were not entirely bad. First, 25% of the 1960 fleet was post-World War II construction, all of which was significantly more capable than the ships it replaced. Second, the Marines were now experimenting with revolutionary concepts and preparing for a new generation of amphibious ships that would look radically different than the existing fleet.
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| USS Thetis Bay (CVHA-1) with her airgroup of HUS-1 Seahorse helicopters |
The most important of these was the Amphibious Assault Ship (LPH). Helicopters had proven themselves during the Korean War and the Marines desired to bring that capability to sea. This was first done in 1957 by converting the
Casablanca-class escort carrier
Thetis Bay (CVE-90) into an Assault Helicopter Carrier (CVHA-1). This fairly basic conversion allowed
Thetis Bay to carry around 1000 troops and land them with an airgroup of around 30 helicopters. This tactic, dubbed "vertical envelopment," would allow Marines to land over a wider area and avoid being tied to a vulnerable beachhead - a vital consideration in an era in which the tactical use of nuclear weapons was considered inevitable. In 1959
Thetis Bay was redesignated LPH-6 and was joined by two converted Essex-class carriers -
Boxer (LPH-4), and
Princeton (LPH-5). The larger size of these ships enabled them to carry around 1450 troops and more cargo as well as operate helicopters more efficiently. However, they were expensive to operate and their basic conversions still left much to be desired.
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| Former Essex-class carrier Boxer (LPH-4) with the same HUS-1 helicopters as the picture of Thetis Bay above |
Part II of this series covers 1960-1975 and can be found here.
