1.
California Shipbuilding Corporation
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California Shipbuilding Corporation built 467 Liberty and Victory ships during World War II, including Haskell-class attack transports. California Shipbuilding Corporation was often referred to as Calship, the Dictionary of American Naval Fighting Ships sometimes refers to this shipyard as California Shipbuilding Co. but Co appears to be an error. The Calship shipyard was created at Terminal Island in Los Angeles, California, bechtel Co. was given sponsorship and executive direction of Calship. As of 1940, Los Angeles shipyards had not built a ship in 20 years. By late 1941 though, shipbuilding had become the second largest manufacturing industry in the Los Angeles area, Calship was created from scratch and began production of Liberty Ships in May 1941. In the early 1940s, contracts from the U. S. Department of Maritime Commission, the yard was located on 175 acres on the north side of Terminal Island, north of Dock Street, near present-day berths 210-213. It initially had 8 ways, and later increased this to 14,40,000 men and women worked under the military contract to construction of 467 vessels over 5 years. The combination of ships were known as the Liberty Fleet. These cargo ships were designed for construction with lower costs for them. Thirteen months after commencing production, the broke the record by delivering 15 Liberty Ships in June 1942. It delivered 111 ships in 1942, more than any other yard in the United States, in June 1943, it broke the record again by delivering 20 ships for the month, and yet again in December 1943, delivering 23 ships. Large Navy contracts developed shipbuilding in California, as a result of that, many workers migrated to the work area. Many shipyards sprang up from San Francisco to San Diego, at the peak of shipbuilding in California were involved 282000 persons. Shipbuilding became an efficient wartime industry. The building of vessels and the number of jobs in the shipbuilding peaked in mid-1943, the Kaiser Steel plant in Fontana, California was completed in August 1943, which enabled further production increases at Calship. Between September 27,1941 and September 27,1945, the yard launched 467 ships, the Calship yard was known as the city built on invisible stilts. It was situated on ground, and was built on artificial earth supported by 57,000 piles driven into the mud. Shipbuilding commenced before the docks were even completed
2.
Westinghouse Electric Corporation
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The Westinghouse Electric Corporation was an American manufacturing company. It was founded on January 8,1886, as Westinghouse Electric Company and later renamed Westinghouse Electric Corporation by inventor, George Westinghouse had previously founded the Westinghouse Air Brake Company. The corporation purchased CBS broadcasting company in 1995 and became CBS Corporation in 1997, Westinghouse Electric was founded by George Westinghouse in Pittsburgh, Pennsylvania in 1886. The firm became active in developing electric infrastructure throughout the United States, in addition to George Westinghouse, early engineers working for the company included Frank Conrad, Benjamin Garver Lamme, Oliver B. Shallenberger, William Stanley, Nikola Tesla, Stephen Timoshenko and Vladimir Zworykin, early on Westinghouse was a rival to Thomas Edisons electric company. In 1892 Edison was merged with Westinghouses chief AC rival, the Thomson-Houston Electric Company, making even bigger competitor, Westinghouse changed its name to Westinghouse Electric Corporation in 1945. Westinghouse purchased CBS in 1995 and became CBS Corporation in 1997, in 1998, CBS established a brand licensing subsidiary Westinghouse Licensing Corporation. In 1997/1998 the Power Generation Business Unit, headquartered in Orlando, FL, was sold to Siemens AG, a year later, CBS sold all of its nuclear power businesses to British Nuclear Fuels Limited. Soon after, BNFL gained license rights on the Westinghouse trademarks and that company was sold to Toshiba in 2007. The first commercial Westinghouse steam turbine generator, a 1,500 kW unit. The machine, nicknamed Mary-Ann, was the first steam turbine generator to be installed by a utility to generate electricity in the US. George Westinghouse had based his original steam turbine design on designs licensed from the English inventor Charles Parsons. or were built overseas under Westinghouse license. Major Westinghouse licensees or joint venture partners included Mitsubishi Heavy Industries of Japan and Harbin Turbine Co. Westinghouse boasted 50,000 employees by 1900, and established a formal research and development department in 1906. While the company was expanding, it would experience internal financial difficulties, during the Panic of 1907, the Board of Directors forced George Westinghouse to take a six-month leave of absence. Westinghouse officially retired in 1909 and died years later in 1914. Under new leadership, Westinghouse Electric diversified its business activities in electrical technology and it acquired the Copeman Electric Stove Company in 1914 and Pittsburgh High Voltage Insulator Company in 1921. Westinghouse also moved into broadcasting by establishing Pittsburghs KDKA, the first commercial radio station. Westinghouse expanded into the business, establishing the Westinghouse Elevator Company in 1928
3.
Joshua Hendy Iron Works
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The Joshua Hendy Iron Works was an American engineering company that existed from the 1850s to the late 1940s. It was at one time a leader in mining technology and its equipment was used to build the Panama Canal. The company was named for its founder Joshua Hendy, born in Cornwall, England in 1822, Hendy at the age of 13 migrated with two brothers to South Carolina in the United States. Hendy built Californias first redwood lumber mill, the Benicia Sawmill, in 1856, he established the Joshua Hendy Iron Works in San Francisco to supply equipment to Gold Rush placer miners. The Hendy plant supplied various equipment to the mining industry, Hendy giant hydraulic crushers were used to excavate the Panama Canal. After Joshua Hendy died in 1891, management of the company was taken over by his nephews Samuel, in 1906 a fire devastated the original San Francisco factory, and the company was re-established in Sunnyvale, California after the local government enticed the company with free land. During World War I, the Hendy plant gained its first experience building marine engines by supplying 11 triple expansion engines for cargo ships built by Western Pipe & Steel. Each engine weighed about 137 tons and stood 24½ feet high, although the first marine engines built by Hendy, they proved to be reliable, with most providing many years of service. Essentially the same engine was used for production of US Liberty ship engines in World War II. In the early 1920s, Hendys hydraulic mining equipment was used in the regrading of Seattle, with the onset of the Great Depression however, and hampered by indifferent management, the Hendy Iron Works - like many other heavy equipment manufacturers of the era - fell on hard times. The company adapted by finding new markets, for example by contracting for the building of giant gates and valves for the schemes of the Hoover, Boulder. During this period it also produced equipment as diverse as crawler tractors, freight car wheel pullers, parts for internal combustion engines, some of the ornate street lamps built by the company can still be seen in San Franciscos Chinatown district today. By the late 1930s the company was in difficulties and had shrunk to a shadow of its former self. The company was in the process of being taken over by the Bank of California in 1940 when businessman Charles E. Moore, with the support of the Six Companies. By 1942, with the US governments wartime Emergency Shipbuilding Program getting underway, the company was then contracted to build 118 triple expansion steam engines for the Liberty ships. As the war progressed and the shipbuilding program continued to expand. Moore responded by streamlining production at the Joshua Hendy plant and he introduced more advanced assembly line techniques, standardizing on more production parts and enabling less skilled workers to accomplish tasks formerly carried out by skilled machinists. By 1943, the company had reduced the required to manufacture a marine steam engine from 4,500 hours to 1,800 hours
4.
Allis-Chalmers
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Allis-Chalmers was a U. S. manufacturer of machinery for various industries. It was reorganized in 1912 as the Allis-Chalmers Manufacturing Company, in the 1980s and 1990s a series of divestitures transformed the firm and eventually dissolved it. Its successors today are Allis-Chalmers Energy and AGCO, author-photographer Randy Leffingwell aptly summarized the firms origins and character. He observed that it grew by acquiring and consolidating the innovations of various firms and building upon them. Financial successes and failures brought them together, former marketing executive Walter M. Buescher said that Allis-Chalmers was a conglomerate before the word was coined. Edward P. Allis was an entrepreneur who in 1860 bought a bankrupt firm at an auction, the Reliance Works of Milwaukee, Wisconsin. Decker & Seville were millwrights who made equipment for flour milling, under Alliss management, the firm was reinvigorated and began producing steam engines and other mill equipment just at the time that many sawmills and flour mills were converting to steam power. Although the financial panic of 1873 caught Edward Allis overextended and forced him into bankruptcy, his own reputation saved him and reorganization came quickly, forming the Edward P. Allis Company. Allis died in 1889, but under his sons and the principals, the firm continued to prosper. Thomas Chalmers was a Scottish immigrant to America who came to the U. S. about 1842, by 1844 he was at Chicago, Illinois and had found work with P. W. Gates, whose foundry and blacksmithing shops produced plows, wagons, and flour-milling equipment. The Gates firm built the first steam-operated sawmill in the country at a time when Chicago was the producer of milled lumber in the country. In 1872, Thomas Chalmers founded the Fraser & Chalmers firm to manufacture mining machinery, boilers, by 1880 steam engines were part of the product line and by 1890, the firm had become one of the worlds largest manufacturers of mining equipment. Thomas Chalmerss son, William James Chalmers, was president of the company from circa 1890 to 1901, meanwhile, the Gates Iron Works, with Chalmers family involvement, had become a manufacturer of crushers, pulverizers, and other rock and cement milling equipment. Another Scottish immigrant family, the Dickson family, came to Canada, by 1852, they had organized a small machine shop and foundry in Scranton, Pennsylvania. In 1856 Thomas Dickson became its president, and in 1862 the firm incorporated as the Dickson Manufacturing Company, by 1900 they were building boilers, steam engines, locomotives, internal combustion engines, blowers, and air compressors. By 1901 the principals of the Edward P. Allis, Fraser & Chalmers, edwin Reynolds believed Allis could control the industrial engine business. In May 1901 the Allis-Chalmers Company was formed and it acquired Dicksons industrial engine business. Dicksons locomotive business was rolled into the new consolidation, the American Locomotive Company
5.
Boiler
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A boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil, the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation. The pressure vessel of a boiler is usually made of steel, stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. In live steam models, copper or brass is used because it is more easily fabricated in smaller size boilers. For much of the Victorian age of steam, the material used for boilermaking was the highest grade of wrought iron. In the 20th century, design practice instead moved towards the use of steel, which is stronger and cheaper, with welded construction, which is quicker and requires less labour. It should be noted, however, that wrought iron boilers corrode far slower than their steel counterparts. This makes the longevity of older wrought-iron boilers far superior to those of welded steel boilers, cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed boilers in some countries, their purpose is usually to produce hot water, not steam, the brittleness of cast iron makes it impractical for high-pressure steam boilers. The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is used as a heat source for generating steam, either directly or, in most cases. Heat recovery steam generators use the heat rejected from other such as gas turbine. 18th century Haycock boilers generally produced and stored large volumes of very low-pressure steam and these could burn wood or most often, coal. Flued boiler with one or two large flues—an early type or forerunner of fire-tube boiler, fire-tube boiler, Here, water partially fills a boiler barrel with a small volume left above to accommodate the steam. This is the type of boiler used in nearly all steam locomotives, the heat source is inside a furnace or firebox that has to be kept permanently surrounded by the water in order to maintain the temperature of the heating surface below the boiling point. Fire-tube boilers usually have a low rate of steam production. Fire-tube boilers mostly burn solid fuels, but are adaptable to those of the liquid or gas variety. Water-tube boiler, In this type, tubes filled with water are arranged inside a furnace in a number of possible configurations and this type generally gives high steam production rates, but less storage capacity than the above
6.
Landing Craft Mechanized
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The landing craft mechanized also landing craft mechanical is a landing craft designed for carrying vehicles. They came to prominence during the Second World War when they were used to land troops or tanks during Allied amphibious assaults. There was no design of LCM used, unlike the landing craft, vehicle, personnel or landing craft assault landing craft made by the US. There were several different designs built by the UK and US, the British motor landing craft was conceived and tested in the 1920s and was used from 1924 in exercises. It was the first purpose built landing craft. It was the progenitor of all subsequent LCM designs, the landing craft, mechanised Mark I was an early British model. It was able to be slung under the davits of a liner or on a cargo ship boom with the result that it was limited to a 16-ton tank, the LCM Mark I was used during the Allied landings in Norway, and at Dieppe and some 600 were built. Displacement,35 tonnes Length,13.6 m Width,4.27 m Draught,1.22 m Machinery, approximately 150 were built by American Car & Foundry and Higgins Industries. A Higgins LCM-3 is on display at the Battleship Cove maritime museum in Fall River, outwardly, the LCM was almost completely identical to a late model LCM - the difference lay inside the pontoon. Here special bilge pumps and special ballast tanks allowed the LCM to alter trim to increase stability when partially loaded, British model of LCM An LCM extended by 6 feet amidships. Many were later adapted as armoured troop carriers for the Mobile Riverine Force in the Vietnam War, power plant,2 Detroit 6-71 diesel engines,348 hp sustained, twin shaft, or 2 Detroit 8V-71 diesel engines,460 hp sustained, twin shaft Length,56
7.
LCVP (United States)
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The landing craft, vehicle, personnel or Higgins boat was a landing craft used extensively in amphibious landings in World War II. The craft was designed by Andrew Higgins based on boats made for operating in swamps, more than 20,000 were built, by Higgins Industries and licensees. Typically constructed from plywood, this shallow-draft, barge-like boat could ferry a platoon-sized complement of 36 men to shore at 9 knots. Men generally entered the boat by climbing down a cargo net hung from the side of their troop transport, they exited by charging down the boats bow ramp. Satisfactory in most respects, the major drawback appeared to be that equipment had to be unloaded. However, it was put into production and service as the craft, personnel. The LCP had two gun positions at the bow. The LCP, commonly called the U-boat or the Higgins boat, was supplied to the British, to whom it was known as the R-boat. Within one month, tests of the ramp-bow Eureka boat in Lake Pontchartrain showed conclusively that successful operation of such a boat was feasible and this boat became the Landing Craft, Personnel or LCP. The machine gun positions were still at the front of the boat, the design was still not ideal, because the ramp was a bottleneck for the troops, as was the case with the British Landing Craft Assault of the year before. The next step was to fit a full-width ramp, now troops could leave en masse and a small vehicle such as a Jeep could be carried, this new version became the LCVP, or simply, the Higgins boat. The machine gun positions were moved to the rear of the boat, at just over 36 ft long and just under 11 ft wide, the LCVP was not a large craft. Powered by a 225-horsepower Diesel engine at 12 knots, it would sway in choppy seas, since its sides and rear were made of plywood, it offered limited protection from enemy fire. The Higgins boat could hold either a 36-man platoon, a jeep and its shallow draft enabled it to run up onto the shoreline, and a semi-tunnel built into its hull protected the propeller from sand and other debris. The steel ramp at the front could be lowered quickly and it was possible for the Higgins boat to swiftly disembark men and supplies, reverse itself off the beach, and head back out to the supply ship for another load within three to four minutes. If Higgins had not designed and built those LCVPs, we never could have landed over an open beach, the whole strategy of the war would have been different. Only a few Higgins boats have survived, often with modifications for post-War use. A remarkably preserved Higgins boat, with the original Higgins motor, was discovered in a yard in Valdez, Alaska
8.
LCPL
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The Landing Craft Personnel or LCP was a landing craft used extensively in the Second World War. Its primary purpose was to ferry troops from ships to attack enemy-held shores. The craft derived from a prototype designed by the Eureka Tug-Boat Company of New Orleans, Louisiana, manufactured initially in boatyards in and around New Orleans, as requirements grew it was produced in a number of yards around the United States. Typically constructed of planks and plywood, and fitted with some armor plate. Men generally entered the boat by walking over a gangplank from the deck of their troop transport as the LCP hung from its davits. When loaded, the LCP was lowered into the water, soldiers exited the boat by jumping or climbing down from the craft’s bow or sides. During the 1930s, the United States Marine Corps sought boats practical for landing troops on beaches, in 1936, the USMC conducted experiments with new types of boats, lighters, and launches. Many craft were considered coming from the Navy’s Bureau as well as fishing boat designs. Included in these experiments were some prototypes where, upon beaching, the craft was based on the company’s 1926 spoonbill-bowed craft used by trappers in the bayous of the Mississippi River delta. The boat’s draft was rather shallow,18 inches, and it could cut through vegetation and it could also run up on shore and extract itself damage-free. As part of demonstrations, boats were often run up on the seawalls of Lake Pontchartrain. The Marines specifications at the time were for boats operated by a crew of 6 that could carry a squad of 12 men, such boats should be able to achieve 15 knots, and to be hoisted on the US Navys standard davits. He produced the 32 feet Eureka or Higgins boat and this was the craft first used in American Fleet Landing Exercises in 1941. Before the USMC received their boats, the British Admiralty’s need for a raiding craft brought the first enquiries for a larger boat. Purchasing agents from Britain had become aware of Andrew Higgins’ Eureka boats, enquiries were made, the German occupation of France had changed British procurement plans dramatically. An initial order for 136 was placed, and the first 50 were delivered to Britain in October 1940, Higgins had already built these boats on spec and is said to have preferred this larger craft. Further US procurements were of this boat, and thus the LCP was the forerunner of all American LCP types. The LCPs were also known as Eurekas or R boats, before 1942, The USMC referred to them as T Boats
9.
5"/38 caliber gun
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The Mark 12 5/38 caliber gun was a US naval gun. The gun was installed into Single Purpose and Dual Purpose mounts used primarily by the US Navy, the 38 caliber barrel was a mid-length compromise between the previous United States standard 5/51 low-angle gun and 5/25 anti-aircraft gun. The increased barrel length provided greatly improved performance in both anti-aircraft and anti-surface roles compared to the 5/25 gun, however, except for the barrel length and the use of semi-fixed ammunition, the 5/38 gun was derived from the 5/25 gun. Both weapons had power ramming, which enabled rapid fire at high angles against aircraft, the 5/38 entered service on USS Farragut, commissioned in 1934. The base ring mount, which improved the rate of fire, entered service on USS Gridley. Even this advanced system required nearly 100 rounds of ammunition expenditure per aircraft kill, however, the planes were normally killed by shell fragments and not direct hits, barrage fire was used, with many guns firing in the air at the same time. Base ring mounts with integral hoists had a rate of fire of 15 rounds per minute per barrel, however. On pedestal and other mounts lacking integral hoists,12 to 15 rounds per minute was the rate of fire, useful life expectancy was 4600 effective full charges per barrel. The 5/38 cal gun was mounted on a large number of US Navy ships in the World War II era. It was backfitted to many of the World War I-era battleships during their wartime refits and it has left active US Navy service, but it is still on mothballed ships of the United States Navy reserve fleets. It is also used by a number of nations who bought or were given US Navy surplus ships, each mount carries one or two Mk 12 5/38cal Gun Assemblies. The gun assembly shown is used in single mounts, and it is the gun in twin mounts. It is loaded from the left side, the left gun in twin mounts is the mirror image of the right gun, and it is loaded from the right side. The Mk12 gun assembly weighs 3,990 lb, the major Mk12 Gun Assembly characteristics are,158 Semi-automatic During recoil, some of the recoil energy is stored in the counter-recoil system. That stored energy is used during counter-recoil to prepare the gun for the next round, the firing pin is cocked, the breech is opened, the spent powder case is ejected, and the bore is air cleaned. Hand loaded A Projectile-Man and a Powder-Man are stationed at each gun assembly and their job is to move the round, consisting of a projectile and a powder case, from the hoists to the rammer tray, and then start the ram cycle. The hydraulically driven Rammer Spade, called the Power Spade in that picture, is at the back of the Rammer Tray, if the multiple names of the Spade is confusing, look at this footnote. Vertical sliding-wedge breech block The breech block closes the chamber behind the powder case and it also holds the firing pin assembly
10.
Bofors 40 mm gun
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The Bofors 40 mm gun, often referred to simply as the Bofors gun, is an anti-aircraft/multi-purpose autocannon designed in the 1930s by the Swedish arms manufacturer AB Bofors. It was one of the most popular medium-weight anti-aircraft systems during World War II, a small number of these weapons remain in service to this day, and saw action as late as the Gulf War. In the post-war era the original design was not suitable for action against jet powered aircraft, so Bofors introduced a new model of more power. In spite of sharing almost nothing with the design other than the calibre and the distinctive conical flash hider. Although not as popular as the original L/60 model, the L/70 remains in service to this day, especially as a weapon for light armored vehicles. Bofors itself has been part of BAE Systems AB since March 2005, the Swedish Navy purchased a number of 2 pounder Pom-Poms from Vickers as anti-aircraft guns in 1922. The Navy approached Bofors about the development of a capable replacement. Bofors signed a contract in late 1928, Bofors produced a gun that was a smaller version of a 57 mm semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspong. Their first test gun was a re-barreled Nordenfelt version of the Finspong gun, testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism that was enough to handle the stresses of moving the large round was too heavy to move quickly enough to fire rapidly. One attempt to solve this problem used zinc shell cases that burned up when fired and this proved to leave heavy zinc deposits in the barrel, and had to be abandoned. This seemed to be the solution they needed, improving firing rates to a level. During this period Krupp purchased a share of Bofors. Krupp engineers started the process of updating the Bofors factories to use equipment and metallurgy. The prototype was completed and fired in November 1931, and by the middle of the month it was firing strings of two and three rounds. Changes to the mechanism were all that remained, and by the end of the year it was operating at 130 rounds per minute. Continued development was needed to turn it into a suitable for production. Since acceptance trials had been passed the year before, this known as the 40 mm akan M/32
11.
Oerlikon 20 mm cannon
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The Oerlikon 20 mm cannon is a series of autocannons, based on an original German 20 mm Becker design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II, and many still in use today. During World War I, the German Reinhold Becker developed a 20 mm caliber cannon and this used a 20x70 RB cartridge and had a cyclic rate of fire of 300 rpm. It was used on a scale as an aircraft gun on Luftstreitkräfte warplanes. Because the Treaty of Versailles banned further production of weapons in Germany. SEMAG continued development of the weapon, and in 1924 had produced the SEMAG L, the Oerlikon firm, named after the Zürich suburb where it was based, then acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. In 1927 the Oerlikon S was added to the product line. This fired a larger cartridge to achieve a muzzle velocity of 830 m/s, at the cost of increased weight. The purpose of development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon. An improved version known as the 1S followed in 1930, three sizes of gun with their different ammunition and barrel length, but very similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the AF and AL, designed to be used in flexible mounts, the 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds. In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft, designated with FF for Flügelfest meaning wing-mounted, these weapons were again available in the three sizes, with designations FF, FFL and FFS. The FF fired a larger cartridge than the AF, 20x72RB. The FF weighed 24 kg and achieved a velocity of 550 to 600 m/s with a rate of fire of 520 rpm. The FFL of 30 kg fired a projectile at a velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high velocity of 830 m/s at a rate of fire of 470 rpm. Apart from changes to the design of the guns for wing-mounting and remote control, for the FF series drum sizes of 45,60,75 and 100 rounds were available, but most users chose the 60-round drum. The 1930s were a period of global re-armament, and a number of foreign firms took licenses for the Oerlikon family of aircraft cannon
12.
Amphibious assault ship
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An amphibious assault ship is a type of amphibious warfare ship employed to land and support ground forces on enemy territory by an amphibious assault. The design evolved from aircraft carriers converted for use as helicopter carriers, coming full circle, some amphibious assault ships now have a secondary role as aircraft carriers, supporting V/STOL fixed-wing aircraft. Most of these ships can carry or support landing craft. The largest fleet of these types is operated by the United States Navy, including the Tarawa class dating back to the 1970s and this does not include the amphibious transport dock, and dock landing ship. In the Pacific theater of World War II, escort carriers would often escort the landing ships, in this role, they would provide air cover for the troopships as well as fly the first wave of attacks on the beach fortifications in amphibious landing operations. In addition, they would also transport aircraft and spare parts from the US to the remote island airstrips, despite all the progress that was seen during World War II, there were still fundamental limitations in the types of coastline that were suitable for assault. Beaches had to be free of obstacles, and have the right tidal conditions. However, the development of the helicopter fundamentally changed the equation, the first use of helicopters in an amphibious assault came during the invasion of Egypt during the Suez War in 1956. In this engagement, two British light fleet carriers, Ocean and Theseus, were converted to perform an airborne assault with helicopters. The techniques were developed further by American forces during the Vietnam War, the modern amphibious assault can take place at virtually any point of the coast, making defending against them extremely difficult. Most early amphibious assault ships were converted from small aircraft carriers and their sister ship HMS Hermes was also converted to a commando carrier in the early 1970s, but was restored to aircraft carrier operations before the end of the 1970s. Later amphibious assault craft were constructed for the role, the United States Navy is also designing a new class of assault ships, the first America-class ship entered service in October 2014. The first British ship to be constructed specifically for the assault role was HMS Ocean. Most modern amphibious assault ships have a deck, allowing them to launch landing craft in rougher seas than a ship that has to use cranes or a stern ramp. Due to their aircraft carrier heritage, all amphibious assault ships resemble aircraft carriers in design, landing craft are also carried, either on deck-mounted davits, or in an internal well deck
