Iowa-class battleship

The vessels that eventually became the Iowa-class battleships were born from the U.S. Navy's War Plan Orange, a Pacific war plan against Japan. War planners anticipated that the U.S. fleet would engage and advance in the Central Pacific, with a long line of communication and logistics that would be vulnerable to high-speed Japanese cruisers and capital ships. The chief concern was that the U.S. Navy's traditional 21-knot battle line of "Standard-type" battleships would be too slow to force these Japanese task forces into battle, while faster aircraft carriers and their cruiser escorts would be outmatched by the Japanese s, which had been upgraded in the 1930s to fast battleships. As a result, the U.S. Navy envisioned a fast detachment of the battle line that could bring the Japanese fleet into battle. Even the new standard battle line speed of 27 knots, as the preceding and battleships were designed for, was not considered enough and during their development processes, designs that could achieve over 30 knots in order to counter the threat of fast "big gun" ships were seriously considered. At the same time, a special strike force consisting of fast battleships operating alongside carriers and destroyers was being envisaged; such a force could operate independently in advance areas and act as scouts. This concept eventually evolved into the Fast Carrier Task Force, though initially the carriers were believed to be subordinate to the battleship. Another factor was the "escalator clause" of the Second London Naval Treaty, which reverted the gun caliber limit from to . Japan had refused to sign the treaty and in particular refused to accept the 14-inch gun caliber limit or the 5:5:3 ratio of warship tonnage limits for Britain, the United States, and Japan, respectively. This resulted in the three treaty powers, the United States, Britain, and France, invoking the caliber escalator clause after April 1937. Circulation of intelligence evidence in November 1937 of Japanese capital ships violating naval treaties caused the treaty powers to expand the escalator clause in June 1938, which amended the standard displacement limit of battleships from to . == Design ==

Early studies Work on what would eventually become the Iowa-class battleship began on the first studies in early 1938, at the direction of Admiral Thomas C. Hart, head of the General Board, following the planned invocation of the "escalator clause" that would permit maximum standard capital ship displacement of . Using the additional over previous designs, the studies included schemes for "slow" battleships that increased armament and protection as well as "fast" battleships capable of or more. One of the "slow" designs was an expanded South Dakota class carrying either twelve 16-inch/45 caliber Mark 6 guns or nine /48 guns and with more armor and a power plant large enough to drive the larger ship through the water at the same 27-knot maximum speed as the South Dakotas. While the "fast" studies would result in the Iowa class, the "slow" design studies would eventually settle on twelve 16-inch guns and evolve into the design for the after all treaty restrictions were removed following the start of World War II. Priority was given to the "fast" design in order to counter and defeat Japan's Kongō-class fast battleships, whose higher speed advantage over existing U.S. battleships might let them "penetrate U.S. cruisers, thereby making it 'open season' on U.S. supply ships". Therefore overwhelming the Japanese battle line was a major driving force in setting the design criteria for the new ships, as was the restricting width of the Panama Canal. For "fast" battleships, one such design, pursued by the Design Division section of the Bureau of Construction and Repair, was a "cruiser-killer". Beginning on 17 January 1938, under Captain A.J. Chantry, the group drew up plans for ships with twelve 16-inch and twenty guns, Panamax capability but otherwise unlimited displacement, a top speed of and a range of when traveling at the more economical speed of . Their plan fulfilled these requirements with a ship of standard displacement, but Chantry believed that more could be done if the ship were to be this large; with a displacement greater than that of most battleships, its armor would have protected it only against the weapons carried by heavy cruisers. Three improved plans – "A", "B", and "C" – were designed at the end of January. An increase in draft, vast additions to the armor, and the substitution of twelve guns in the secondary battery were common among the three designs. "A" was the largest, at standard, and was the only one to still carry the twelve 16-inch guns in four triple turrets (3-gun turrets according to US Navy). It required to make . "B" was the smallest at standard; like "A" it had a top speed of 32.5 knots, but "B" only required to make this speed. It also carried only nine 16-inch guns, in three triple turrets. "C" was similar but added (for a total of ) to meet the original requirement of . The weight required for this and a longer belt – , compared with for "B" – meant that the ship was standard. Design history In March 1938, the General Board followed the recommendations of the Battleship Design Advisory Board, which was composed of the naval architect William Francis Gibbs, William Hovgaard (then president of New York Shipbuilding), John Metten, Joseph W. Powell, and the long-retired Admiral and former Chief of the Bureau of Ordnance Joseph Strauss. The board requested an entirely new design study, again focusing on increasing the size of the South Dakota class. The first plans made for this indicated that was possible on a standard displacement of about . could be bought with and a standard displacement of around , which was well below the London Treaty's "escalator clause" maximum limit of . These designs were able to convince the General Board that a reasonably well-designed and balanced 33-knot "fast" battleship was possible within the terms of the "escalator clause". However, further studies revealed major problems with the estimates. The speed of the ships meant that more freeboard would be needed both fore and amidships, the latter requiring an additional foot of armored freeboard. Along with this came the associated weight in supporting these new strains: the structure of the ship had to be reinforced and the power plant enlarged to avoid a drop in speed. In all, about had to be added, and the large margin the navy designers had previously thought they had – roughly – was suddenly vanishing. The draft of the ships was also allowed to increase, which enabled the beam to narrow and thus reduced the required power (since a lower beam-to-draft ratio reduces wave-making resistance). This also allowed the ships to be shortened, which reduced weight. With the additional displacement, the General Board was incredulous that a tonnage increase of would allow only the addition of over the South Dakotas. Rather than retaining the 16-inch/45 caliber Mark 6 guns used in the South Dakotas, they ordered that the preliminary design would have to include the more powerful but significantly heavier 16-inch/50 caliber Mark 2 guns left over from the canceled s and battleships of the early 1920s. The 16"/50 turret weighed some more than the 16"/45 turret already in use and also had a larger barbette diameter of compared to the latter's barbette diameter of , so the total weight gain was about . This put the ship at a total of – well over the limit. An apparent savior appeared in a Bureau of Ordnance preliminary design for a turret that could carry the 50-caliber guns and also fit in the smaller barbette of the 45-caliber gun turret. Other weight savings were achieved by thinning some armor elements and substituting construction steel with armor-grade Special Treatment Steel (STS) in certain areas. The net savings reduced the preliminary design displacement to standard, though the margin remained tight. This breakthrough was shown to the General Board as part of a series of designs on 2 June 1938. However, the Bureau of Ordnance continued working on the turret with the larger barbette, while the Bureau of Construction and Repair used the smaller barbettes in the contract design of the new battleships. As the bureaus were independent of one another, they did not realize that the two plans could not go together until November 1938, when the contract design was in the final stages of refinement. By this time, the ships could not use the larger barbette, as it would require extensive alterations to the design and would result in substantial weight penalties. Reverting to the 45-caliber gun was also deemed unacceptable. The General Board was astounded; one member asked the head of the Bureau of Ordnance if it had occurred to him that Construction and Repair would have wanted to know what turret his subordinates were working on "as a matter of common sense". A complete scrapping of plans was avoided only when designers within the Bureau of Ordnance were able to design a new 50-caliber gun, the Mark 7, that was both lighter and smaller in outside diameter; this allowed it to be placed in a turret that would fit in the smaller barbette. The redesigned 3-gun turret, equipped as it was with the Mark 7 naval gun, provided an overall weight saving of nearly to the overall design of the Iowa class. The contract design displacement subsequently stood at standard and full load. In May 1938, the United States Congress passed the Second Vinson Act, which "mandated a 20% increase in strength of the United States Navy". The act was sponsored by Carl Vinson, a Democratic Congressman from Georgia who was Chairman of the House Naval Affairs and Armed Services Committee. The Second Vinson Act updated the provisions of the Vinson-Trammell Act of 1934 and the Naval Act of 1936, which had "authorized the construction of the first American battleships in 17 years", based on the provisions of the London Naval Treaty of 1930; this act was quickly signed by President Franklin D. Roosevelt and provided the funding to build the Iowa class. Each ship cost approximately US$100 million. As 1938 drew to a close, the contract design of the Iowas was nearly complete, but it would continuously evolve as the New York Navy Yard, the lead shipyard, conducted the final detail design. These revisions included changing the design of the foremast, replacing the original /75-caliber guns that were to be used for anti-aircraft (AA) work with /70 caliber Oerlikon cannons and /56 caliber Bofors guns, and moving the combat information center into the armored hull. Additionally, in November 1939, the New York Navy Yard greatly modified the internal subdivision of the machinery rooms, as tests had shown the underwater protection in these rooms to be inadequate. The longitudinal subdivision of these rooms was doubled, and the result of this was clearly beneficial: "The prospective effect of flooding was roughly halved and the number of uptakes and hence of openings in the third deck greatly reduced." Although the changes meant extra weight and increasing the beam by to , this was no longer a major issue; Britain and France had renounced the Second London Naval Treaty soon after the beginning of the Second World War. The design displacement was standard, approximately 2% overweight, when Iowa and New Jersey were laid down in June and September 1940. By the time the Iowas were completed and commissioned in 1943–44, the considerable increase in anti-aircraft armament – along with their associated splinter protection and crew accommodations – and additional electronics had increased standard displacement to some , while full load displacement became . ==Specifications==

General characteristics camouflage pattern, c. 1944. The Iowa-class battleships are long at the waterline and long overall with a beam of . During World War II, the draft was at full load displacement of and at design combat displacement of . Like the two previous classes of American fast battleships, the Iowas have a double bottom hull that becomes a triple bottom under the armored citadel and armored skegs around the inboard shafts. The dimensions of the Iowas were strongly influenced by speed. When the Second Vinson Act was passed by the United States Congress in 1938, the U.S. Navy moved quickly to develop a 45,000-ton-standard battleship that would pass through the wide Panama Canal. Drawing on a 1935 empirical formula for predicting a ship's maximum speed based on scale-model studies in flumes of various hull forms and propellers and a newly developed empirical theorem that related waterline length to maximum beam, the Navy drafted plans for a battleship class with a maximum beam of which, when multiplied by 7.96, produced a waterline length of . The Navy also called for the class to have a lengthened forecastle and amidship, which would increase speed, and a bulbous bow. The Iowas exhibit good stability, making them steady gun platforms. At design combat displacement, the ships' (GM) metacentric height was . They also have excellent maneuverability in the open water for their size, while seakeeping is described as good, but not outstanding. In particular, the long fine bow and sudden widening of the hull just in front of the foremost turret contributed to the ships being rather wet for their size. This hull form also resulted in very intense spray formations, which led to some difficulty refueling escorting destroyers. Armament Main battery The primary guns used on these battleships are the nine /50-caliber Mark 7 naval guns, a compromise design developed to fit inside the barbettes. These guns fire high explosive- and armor-piercing shells and can fire a 16-inch shell approximately . The guns are housed in three 3-gun turrets: two forward of the battleship's superstructure and one aft, in a configuration known as "2-A-1". The guns are long (50 times their 16-inch bore, or 50 calibers from breechface to muzzle). About protrudes from the gun house. Each gun weighs about without the breech, or with the breech. Each gun rests within an armored turret, but only the top of the turret protrudes above the main deck. The turret extends either four decks (Turrets 1 and 3) or five decks (Turret 2) down. The lower spaces contain rooms for handling the projectiles and storing the powder bags used to fire them. Each turret required a crew of between 85 and 110 men to operate. The large-caliber guns were designed to fire two different conventional 16-inch shells: the Mk 8 "Super-heavy" APC (Armor Piercing, Capped) shell for anti-ship and anti-structure work, and the Mk 13 high-explosive round designed for use against unarmored targets and shore bombardment. When firing the same conventional shell, the 16-inch/45 caliber Mark 6 used by the fast battleships of the North Carolina and South Dakota classes had a slight advantage over the 16-inch/50 caliber Mark 7 gun when hitting deck armor – a shell from a 45 cal gun would be slower, meaning that it would have a steeper trajectory as it descended. At , a shell from a 45 cal would strike a ship at an angle of 45.2 degrees, as opposed to 36 degrees with the 50 cal. The Mark 7 had a greater maximum range over the Mark 6: vs . In the 1950s, the W23, an adaptation of the W19 nuclear artillery shell, was developed specifically for the 16-inch guns. The shell weighed , had an estimated yield of , and its introduction made the Iowa-class battleships' 16-inch guns the world's largest nuclear artillery and made these four battleships the only US Navy ships ever to have nuclear shells for naval guns. Although developed for exclusive use by the battleship's guns it is not known if any of the Iowas actually carried these shells while in active service due to the United States Navy's policy of refusing to confirm or deny the presence of nuclear weaponry aboard its ships. In 1991, the United States unilaterally withdrew all of its nuclear artillery shells from service, and the dismantling of the US nuclear artillery inventory is said to have been completed in 2004. Secondary battery of the United States Marine Corps aboard the battleship . In keeping with tradition, a 5-inch gun mount on each Iowa-class battleship was manned by the ship's Marine Detachment. The Iowas carried twenty /38 caliber Mark 12 guns in ten Mark 28 Mod 2 enclosed base ring mounts. Originally designed to be mounted upon destroyers built in the 1930s, these guns were so successful that they were added to many American ships during the Second World War, including every major ship type and many smaller warships constructed between 1934 and 1945. They were considered to be "highly reliable, robust and accurate" by the Navy's Bureau of Ordnance. Each 5-inch/38 gun weighed almost without the breech; the entire mount weighed . It was long overall, had a bore length of , and a rifling length of . The gun could fire shells at about ; about 4,600 could be fired before the barrel needed to be replaced. Minimum and maximum elevations were −15 and 85 degrees, respectively. The guns' elevation could be raised or lowered at about 15 degrees per second. The mounts closest to the bow and stern could aim from −150 to 150 degrees; the others were restricted to −80 to 80 degrees. They could be turned at about 25 degrees per second. The mounts were directed by four Mark 37 fire control systems primarily through remote power control (RPC). When the Iowa-class battleships were commissioned in 1943 and 1944, they carried twenty quad 40 mm AA gun mounts, which they used for defense against enemy aircraft. These heavy AA guns were also employed in the protection of Allied aircraft carriers operating in the Pacific Theater of World War II, and accounted for roughly half of all Japanese aircraft shot down between 1 October 1944 and 1 February 1945. Although successful in this role against WWII aircraft, the 40 mm guns were stripped from the battleships in the jet age – initially from New Jersey when reactivated in 1968 and later from Iowa, Missouri, and Wisconsin when they were reactivated for service in the 1980s. Propulsion The powerplant of the Iowas consists of eight Babcock & Wilcox boilers and four sets of double reduction cross-compound geared turbines, with each turbine set driving a single shaft. Specifically, the geared turbines on Iowa and Missouri were provided by General Electric, while the equivalent machinery on New Jersey and Wisconsin was provided by Westinghouse. The plant produced and propelled the ship up to a maximum speed of at full load displacement and at normal displacement. The ships carried of fuel oil which gave a range of at . Two semi-balanced rudders gave the ships a tactical turning diameter of at and at . The machinery spaces were longitudinally divided into eight compartments with alternating fire and engine rooms to ensure adequate isolation of machinery components. Four fire rooms each contained two M-Type boilers operating at with a maximum superheater outlet temperature of . The double-expansion engines consist of a high-pressure (HP) turbine and a low-pressure (LP) turbine. The steam is first passed through the HP turbine which turns at up to 2,100 rpm. The steam, largely depleted at this point, is then passed through a large conduit to the LP turbine. By the time it reaches the LP turbine, it has no more than of pressure left. The LP turbine increases efficiency and power by extracting the last little bit of energy from the steam. After leaving the LP turbine, the exhaust steam passes into a condenser and is then returned as feed water to the boilers. Water lost in the process is replaced by three evaporators, which can make a total of 60,000 US gallons per day (3 liters per second) of fresh water. After the boilers have had their fill, the remaining fresh water is fed to the ship's potable water systems for drinking, showers, hand washing, cooking, etc. All of the urinals and all but one of the toilets on the Iowa class flush with salt water in order to conserve fresh water. The turbines, especially the HP turbine, can turn at 2,000 rpm; their shafts drive through reduction gearing that turns the propeller shafts at speeds up to 225 rpm, depending upon the desired speed of the ship. The Iowas were outfitted with four screws: the outboard pair consisting of four-bladed propellers in diameter and the inboard pair consisting of five-bladed propellers in diameter. The propeller designs were adopted after earlier testing had determined that propeller cavitation caused a drop in efficiency at speeds over . The two inner shafts were housed in skegs to smooth the flow of water to the propellers and improve the structural strength of the stern. Each of the four engine rooms has a pair of 1,250 kW Ship's Service Turbine Generators (SSTGs), providing the ship with a total non-emergency electrical power of 10,000 kW at 450 volts alternating current. Additionally, the vessels have a pair of 250 kW emergency diesel generators. To allow battle-damaged electrical circuits to be repaired or bypassed, the lower decks of the ship have a Casualty Power System whose large 3-wire cables and wall outlets called "biscuits" can be used to reroute power. Electronics (1943–1969) The earliest search radars installed were the SK air-search radar and SG surface-search radar during World War II. They were located on the mainmast and forward fire-control tower of the battleships, respectively. As the war drew to a close, the United States introduced the SK-2 air-search radar and SG surface-search radar; the Iowa class was updated to make use of these systems between 1945 and 1952. At the same time, the ships' radar systems were augmented with the installation of the SP height finder on the main mast. In 1952, AN/SPS-10 surface-search radar and AN/SPS-6 air-search radar replaced the SK and SG radar systems, respectively. Two years later the SP height finder was replaced by the AN/SPS-8 height finder, which was installed on the main mast of the battleships. In addition to these search and navigational radars, the Iowa class were also outfitted with a variety of fire control radars for their gun systems. Beginning with their commissioning, the battleships made use of a pair of Mk 38 gun fire control systems with Mark 8 fire control radar to direct the 16-inch guns and a quartet of Mk 37 gun fire control systems with Mark 12 fire control radar and Mark 22 height finding radar to direct the 5-inch gun batteries. These systems were upgraded over time with the Mark 13 replacing the Mark 8 and the Mark 25 replacing the Mark 12/22, but they remained the cornerstones of the combat radar systems on the Iowa class during their careers. The range estimation of these gunfire control systems provided a significant accuracy advantage over earlier ships with optical rangefinders; this was demonstrated off Truk Atoll on 16 February 1944, when the New Jersey engaged the at a range of and straddled her, setting the record for the longest-ranged straddle in history. In World War II, the electronic countermeasures (ECM) included the SPT-1 and SPT-4 equipment; passive electronic support measures (ESM) were a pair of DBM radar direction finders and three intercept receiving antennas, while the active components were the TDY-1 jammers located on the sides of the fire control tower. The ships were also equipped with the identification, friend or foe (IFF) Mark III system, which was replaced by the IFF Mark X when the ships were overhauled in 1955. When the New Jersey was reactivated in 1968 for the Vietnam War, she was outfitted with the ULQ-6 ECM system. Armor of the battleship New Jersey. The Iowas carried heavy armor protection against shellfire and bombs with significant underwater protection against torpedoes. The Iowas' "all-or-nothing" armor scheme was largely modeled on that of the preceding South Dakota class, and designed to give a zone of immunity against fire from 16-inch/45-caliber guns between away. The protection system consists of Class A face-hardened Krupp cemented (K.C.) armor and Class B homogeneous Krupp-type armor; furthermore, special treatment steel (STS), a high-tensile structural steel with armor properties comparable to Class B, was extensively used in the hull plating to increase protection. The citadel consisting of the magazines and engine rooms was protected by an STS outer hull plating thick and a Class A armor belt thick mounted on STS backing plate; the armor belt is sloped at 19 degrees, equivalent to of vertical class B armor at 19,000 yards. The armor belt extends to the triple bottom, where the Class B lower portion tapers to . The ends of the armored citadel are closed by vertical Class A transverse bulkheads for Iowa and New Jersey. The transverse bulkhead armor on Missouri and Wisconsin was increased to ; this extra armor provided protection from raking fire directly ahead, which was considered more likely given the high speed of the Iowas. The deck armor consists of a STS weather deck, a combined Class B and STS main armor deck, and a STS splinter deck. Over the magazines, the splinter deck is replaced by a STS third deck that separates the magazine from the main armored deck. The powder magazine rooms are separated from the turret platforms by a pair of 1.5-inch STS annular bulkheads under the barbettes for flashback protection. The installation of armor on the Iowas also differed from those of earlier battleships in that the armor was installed while the ships were still "on the way" rather than after the ships had been launched. The Iowas had heavily protected main battery turrets, with Class B and STS face, Class A sides, Class A rear, and Class B roof. The turret barbettes' armor is Class A with abeam and facing the centerline, extending down to the main armor deck. The conning tower armor is Class B with on all sides and on the roof. The secondary battery turrets and handling spaces were protected by of STS. The propulsion shafts and steering gear compartment behind the citadel had considerable protection, with Class A side strake and roof. The armor's immunity zone shrank considerably against guns equivalent to their own 16-inch/50-caliber guns armed with the Mk 8 armor-piercing shell due to the weapon's increased muzzle velocity and improved shell penetration; increasing the armor would have increased weight and reduced speed, a compromise that the General Board was not willing to make. The Iowas' torpedo defense was based on the South Dakotas' design, with modifications to address shortcomings discovered during caisson tests. The system is an internal "bulge" that consists of four longitudinal torpedo bulkheads behind the outer hull plating with a system depth of to absorb the energy of a torpedo warhead. The extension of the armor belt to the triple bottom, where it tapers to a thickness of , serves as one of the torpedo bulkheads and was hoped to add to protection; the belt's lower edge was welded to the triple bottom structure and the joint was reinforced with buttstraps due to the slight knuckle causing a structural discontinuity. The torpedo bulkheads were designed to elastically deform to absorb energy and the two outer compartments were liquid loaded in order to disrupt the gas bubble and slow fragments. The outer hull was intended to detonate a torpedo, with the outer two liquid compartments absorbing the shock and slowing any splinters or debris while the lower armored belt and the empty compartment behind it absorb any remaining energy. However, the Navy discovered in caisson tests in 1939 that the initial design for this torpedo defense system was actually less effective than the previous design used on the North Carolinas due to the rigidity of the lower armor belt causing the explosion to significantly displace the final holding bulkhead inwards despite remaining watertight. To mitigate the effects, the third deck and triple bottom structure behind the lower armor belt were reinforced and the placement of brackets was changed. Iowas' system was also improved over the South Dakotas' through closer spacing of the transverse bulkheads, greater thickness of the lower belt at the triple bottom joint, and increased total volume of the "bulge". The system was further modified for the last two ships of the class, Illinois and Kentucky, by eliminating knuckles along certain bulkheads; this was estimated to improve the strength of the system by as much as 20%. Based on costly lessons in the Pacific theater, concerns were raised about the ability of the armor on these battleships to withstand aerial bombing, particularly high-altitude bombing using armor-piercing bombs. Developments such as the Norden bombsight further fueled these concerns. While the design of the Iowas was too far along to adequately address this issue, experience in the Pacific theater eventually demonstrated that high-altitude unguided bombing was ineffective against maneuvering warships. Aircraft (1943–1969) When they were commissioned during World War II, the Iowa-class battleships came equipped with two aircraft catapults designed to launch floatplanes. Initially, the Iowas carried the Vought OS2U Kingfisher and Curtiss SC Seahawk, both of which were employed to spot for the battleship's main gun batteries – and, in a secondary capacity, perform search-and-rescue missions. By the time of the Korean War, helicopters had replaced floatplanes and the Sikorsky HO3S-1 helicopter was employed. New Jersey made use of the Gyrodyne QH-50 DASH drone for her Vietnam War deployment in 1968–69. == Conversion proposals ==

The Iowa class were the only battleships with the speed required for post-war operations based around fast aircraft carrier task forces. There were several proposals in the early Cold War to convert the class to take into account changes in technology and doctrine. These included plans to equip the class with nuclear missiles, add aircraft capability, and – in the case of Illinois and Kentucky – a proposal to rebuild both as aircraft carriers instead of battleships. Initially, the Iowa class was to consist of only four battleships with hull numbers BB-61 to BB-64: Iowa, New Jersey, Missouri, and Wisconsin. However, changing priorities during World War II resulted in the battleship hull numbers BB-65 and BB-66 being reordered as Illinois and Kentucky, respectively; Montana and Ohio were reassigned to hull numbers BB-67 and BB-68. At the time these two battleships were to be built a proposal was put forth to have them constructed as aircraft carriers rather than fast battleships. The plan called for the ships to be rebuilt to include a flight deck and an armament suite similar to that placed aboard the s that were at the time under construction in the United States. Ultimately, nothing came of the design proposal to rebuild these two ships as aircraft carriers and they were cleared for construction as fast battleships to conform to the Iowa-class design, though they differed from the earlier four that were built. Eventually, the light cruisers were selected for the aircraft-carrier conversion. Nine of these light cruisers would be rebuilt as light aircraft carriers. After the surrender of the Empire of Japan, construction on Illinois and Kentucky stopped. Illinois was eventually scrapped, but Kentuckys construction had advanced enough that several plans were proposed to complete Kentucky as a guided missile battleship (BBG) by removing the aft turret and installing a missile system. A similar conversion had already been performed on the battleship (BB-41/AG-128) to test the RIM-2 Terrier missile after World War II. One such proposal came from Rear Admiral W.K. Mendenhall, Chairman of the Ship Characteristics Board (SCB); Mendenhall proposed a plan that called for $15–30 million to be spent to allow Kentucky to be completed as a guided-missile battleship (BBG) carrying eight SSM-N-8 Regulus II guided missiles with a range of . He also suggested Terrier or RIM-8 Talos launchers to supplement the AA guns and proposed nuclear (instead of conventional) shells for the 16-inch guns. This never materialized, and Kentucky was ultimately sold for scrap in 1958, although her bow was used to repair her sister Wisconsin after a collision on 6 May 1956, earning her the nickname WisKy. In 1954, the Long Range Objectives Group of the United States Navy suggested converting the Iowa-class ships to BBGs. In 1958, the Bureau of Ships offered a proposal based on this idea. This replaced the 5- and 16-inch gun batteries with "two Talos twin missile systems, two RIM-24 Tartar twin missile systems, an RUR-5 ASROC antisubmarine missile launcher, and a Regulus II installation with four missiles", as well as flagship facilities, sonar, helicopters, and fire-control systems for the Talos and Tartar missiles. In addition to these upgrades, of additional fuel oil was also suggested to serve in part as ballast for the battleships and for use in refueling destroyers and cruisers. Due to the estimated cost of the overhaul ($178–193 million) this proposal was rejected as too expensive; instead, the SCB suggested a design with one Talos, one Tartar, one ASROC, and two Regulus launchers and changes to the superstructure, at a cost of up to $85 million. This design was later revised to accommodate the Polaris Fleet Ballistic Missile, which in turn resulted in a study of two schemes by the SCB. In the end, none of these proposed conversions for the battleships were ever authorized. Interest in converting the Iowas into guided-missile battleships began to deteriorate in 1960 because the hulls were considered too old and the conversion costs too high. Nonetheless, additional conversion proposals – including one to install the AN/SPY-1 Aegis Combat System radar on the battleships – were suggested in 1962, 1974, and 1977, but as before, these proposals failed to gain the needed authorization. This was due, in part, to the possibility that sensitive electronics within of any 16-inch gun muzzle may be damaged from overpressure. == 1980s reactivation/modernization ==

In 1980, Ronald Reagan was elected president on a promise to build up the US military as a response to the increasing military power of the Soviet Union. The Soviet Navy was commissioning the of missile cruisers, the largest type of surface combatant since World War II. As part of Reagan's 600-ship Navy policy and as a counter to the Kirov class, the US Navy began reactivating the four Iowa-class units and modernizing them for service. The Navy considered several proposals that would have removed the aft 16-inch turret. Martin Marietta proposed to replace the turret with servicing facilities for 12 AV-8B Harrier STOVL jump jets. A more detailed proposal, the "Interdiction Assault Ship", proposed a V-shaped ramped flight deck (the base of the V would have been on the ship's stern, while each leg of the V would extend forward, so that planes taking off would fly past the ship's exhaust stacks and conning tower), while a new hangar would be added with two elevators, which would support up to twelve McDonnell Douglas AV-8B Harrier II jump-jets. These aviation facilities could also support helicopters, SEAL teams and up to 500 Marines for an air assault. In the empty space between the V flight deck would be up to 320 missile silos accommodating a mixture of Tomahawk land attack missiles, ASROC anti-submarine rockets and Standard surface-to-air missiles. The existing five-inch gun turrets would be replaced with 155-millimeter howitzers for naval gunfire support. Charles Myers, a former Navy test pilot turned Pentagon consultant, proposed replacing the turret with vertical launch systems for missiles and a flight deck for Marine helicopters. In July 1981, the US Naval Institute's Proceedings published a proposal by naval architect Gene Anderson for a canted flight deck with steam catapult and arrestor wires for F/A-18 Hornet fighters. Plans for these conversions were dropped in 1984. Each battleship was overhauled to burn navy distillate fuel and modernized to carry electronic warfare suites, close-in weapon systems (CIWS) for self-defense, and missiles. The obsolete electronics and anti-aircraft armament were removed to make room for more modern systems. The Navy spent about $1.7 billion, from 1981 through 1988, to modernize and reactivate the four Iowa-class battleships, roughly the same as building four s. After modernization, the full load displacement was relatively unchanged at . The modernized battleships operated as centerpieces of their own battle group (termed as a Battleship Battle Group or Surface Action Group), consisting of one , one or , one , three s and one support ship, such as a fleet oiler. Armament During their modernization in the 1980s, each Iowa was equipped with four of the US Navy's Phalanx CIWS mounts, two of which sat just behind the bridge and two which were next to the ship's aft funnel. Iowa, New Jersey, and Missouri were equipped with the Block 0 version of the Phalanx, while Wisconsin received the first operational Block 1 version in 1988. The Phalanx system is intended to serve as a last line of defense against enemy missiles and aircraft, and when activated can engage a target with a 20 mm M61 Vulcan 6-barreled Gatling cannon at a distance of approximately . Owing to the original 1938 design of the battleships, the Tomahawk missiles could not be fitted to the Iowa class unless the battleships were rebuilt in such a way as to accommodate the missile mounts that would be needed to store and launch the Tomahawks. This realization prompted the removal of the anti-aircraft guns previously installed on the Iowas and the removal of four of each of the battleships' ten 5-inch/38 DP mounts. The mid and aft end of the battleships were then rebuilt to accommodate the missile launchers. Owing to the overpressure effects of the main battery, caution zones were implemented for the second and third turrets to prevent accidental destruction of the new equipment. This similarly scuppered plans to install the NATO Sea Sparrow system on the ships. To compensate for this, five FIM-92 Stinger surface-to-air missile firing positions were installed. These secured the shoulder-launched weapons and their rounds for ready use by the crew. Electronics During their modernization under the 600-ship Navy program, the Iowa-class battleships' radar systems were again upgraded. The foremast was of a new tripod design that was considerably reinforced to allow the AN/SPS-6 air-search radar system to be replaced with the AN/SPS-49 radar set (which also augmented the existing navigation capabilities on the battleships), and the AN/SPS-8 surface-search radar set was replaced by the AN/SPS-67 search radar. The new mast also incorporates a Tactical Air Navigation System (TACAN) antenna. By the Korean War, jet engines had replaced propellers on aircraft, which severely limited the ability of the 20 mm and 40 mm AA batteries and their gun systems to track and shoot down enemy planes. Consequently, the AA guns and their associated fire-control systems were removed when reactivated. New Jersey received this treatment in 1967, and the others followed in their 1980s modernizations. In the 1980s, each ship also received a quartet of Phalanx CIWS mounts which made use of a radar system to locate incoming enemy projectiles and destroy them with a 20 mm Gatling gun before they could strike the ship. UAV was used aboard the Iowa-class ships for gunnery spotting. With the added missile capacity of the battleships in the 1980s came additional fire-support systems to launch and guide the ordnance. To fire the Harpoon anti-ship missiles, the battleships were equipped with the SWG-1 fire-control system, and to fire the Tomahawk missiles the battleships used either the SWG-2 or SWG-3 fire-control system. In addition to these offensive-weapon systems, the battleships were outfitted with the AN/SLQ-25 Nixie to be used as a lure against enemy torpedoes; an SLQ-32 electronic warfare system that can detect, jam, and deceive an opponent's radar; and a Mark 36 SRBOC system to fire chaff rockets intended to confuse enemy missiles. During Operation Desert Storm these Pioneers were operated by detachments of VC-6. In addition to the Pioneer UAVs, the recommissioned Iowas could support operations by various types of helicopters, including the UH-1 Iroquois, SH-2 Seasprites, CH-46 Sea Knight, CH-53 Sea Stallion, and LAMPS III SH-60B Seahawk. == Gunfire support role ==

Following the 1991 Gulf War and the subsequent dissolution of the Soviet Union, the United States Navy began to decommission and mothball many of the ships it had brought out of its reserve fleet in the drive to attain a 600-ship Navy. At the height of Navy Secretary John F. Lehman's 600-ship Navy plan, nearly 600 ships of all types were active within the Navy. This included fifteen aircraft carriers, four battleships, and over 100 submarines, along with various other types of ships the overall plan specified. When the Soviet Union collapsed in 1991 the Navy sought to return to its traditional, 313-ship composition. While reducing the fleet created under the 600-ship Navy program, the decision was made to deactivate the four recommissioned Iowa-class battleships and return them to the reserve fleet. , Korea (1953).|alt=A black-and-white photograph of a large caliber gunship on the left side of the picture with the main guns pointed to the top right side of the image. Smoke and flames can be seen from the barrels of the guns as they have just been discharged. A disturbance on the water generated from the pressure of the gun's firing can be seen on the bottom right of the image. In 1995, the decommissioned battleships were removed from the Naval Vessel Register after it was determined by ranking US Navy officials that there was no place for a battleship in the modern navy. In response to the striking of the battleships from the Naval Vessel Register a movement began to reinstate the battleships, on the grounds that these vessels had superior firepower over the 5-inch guns found on the Spruance, Kidd and Arleigh Burke-class destroyers and Ticonderoga-class cruisers. Citing concern over the lack of available gunfire to support amphibious operations, Congress required the Navy to reinstate two battleships to the Naval Vessel Register and maintain them with the mothball fleet, until the Navy could certify it had gunfire support within the current fleet that would meet or exceed the battleship's capability. The debate over battleships in the modern navy continued until 2006, when the two reinstated battleships were stricken after naval officials submitted a two-part plan that called for the near-term goal of increasing the range of the guns in use on the Arleigh Burke-class destroyers with new Extended Range Guided Munition (ERGM) ammunition intended to allow a 5-inch projectile fired from these guns to travel an estimated inland. The long-term goal called for the replacement of the two battleships with 32 vessels of the of guided-missile destroyers. Cost overruns caused the class to be reduced to three ships. These ships are outfitted with an Advanced Gun System (AGS) that was to fire specially developed 6-inch Long Range Land Attack Projectiles for shore bombardment. LRLAP procurement was canceled in 2017 and the AGS is unusable. The long-term goal for the Zumwalt class is to have the ships mount railguns or free-electron lasers. == Cultural significance ==

The Iowa class became culturally symbolic in the United States in many different ways, to the point where certain elements of the American public – such as the United States Naval Fire Support Association – were unwilling to part with the battleships, despite their apparent obsolescence in the face of modern naval combat doctrine that places great emphasis on air supremacy and missile firepower. Although all were officially stricken from the Naval Vessel Register they were spared scrapping and were donated for use as museum ships. Their service records added to their fame, ranging from their work as carrier escorts in World War II to their shore bombardment duties in North Korea, North Vietnam, and the Middle East, as well as their service in the Cold War against the expanded Soviet Navy. Their reputation combined with the stories told concerning the firepower of these battleships' 16-inch guns were such that when they were brought out of retirement in the 1980s in response to increased Soviet Naval activity – and in particular, in response to the commissioning of the s – the United States Navy was inundated with requests from former sailors pleading for a recall to active duty so they could serve aboard one of the battleships. In part because of the service length and record of the class, members have made numerous appearances in television shows, video games, movies, and other media, including appearances of the Kentucky and Illinois in the anime series Neon Genesis Evangelion, the History Channel documentary series Battle 360: USS Enterprise, the Discovery Channel documentary The Top 10 Fighting Ships (where the Iowa class was rated Number 1), the book turned movie A Glimpse of Hell, the 1989 music video for the song by Cher "If I Could Turn Back Time", the 1992 film Under Siege, the 2012 film Battleship, among other appearances. == Ships in class==

in 1954; from front to back is Iowa, Wisconsin, Missouri and New Jersey. When brought into service during the final years of World War II, the Iowa-class battleships were assigned to operate in the Pacific Theatre of World War II. By this point in the war, aircraft carriers had displaced battleships as the primary striking arm of both the United States Navy and the Imperial Japanese Navy. As a result of this shift in tactics, US fast battleships of all classes were relegated to the secondary role of carrier escorts and assigned to the Fast Carrier Task Force to provide anti-aircraft screening for Allied aircraft carriers and perform shore bombardment. Three were recalled to service in the 1950s with the outbreak of the Korean War, and they provided naval artillery support for U.N. forces for the entire duration of the war before being returned to mothballs in 1955 after hostilities ceased. In 1968, to help alleviate US air losses over North Vietnam, New Jersey was summoned to Vietnam, but she was decommissioned a year after arriving. All four returned in the 1980s during the drive for a 600-ship Navy to counter the new Soviet Kirov-class battlecruisers, only to be retired after the collapse of the Soviet Union on the grounds that they were too expensive to maintain. was ordered on 9 September 1940 and laid down on 7 March 1942. Work on the ship was suspended in June 1942, and the hull floated out to make room for the construction of LSTs. The interruption lasted for two and a half years while a parallel aircraft carrier debate played out as with Illinois, reaching the same conclusion. Work resumed in December 1944, with completion projected for mid-1946. Further suggestions were made to convert Kentucky into a specialist anti-aircraft ship, and work was again suspended. With the hull approximately three-quarters completed, she was floated on 20 January 1950, to clear a dry dock for repairs to Missouri, which had run aground. During this period, plans were proposed to convert Kentucky into a guided missile battleship, which saw her reclassified from BB-66 to BBG-1. When these failed construction of any sort, work never resumed and the ship was used as a parts hulk; in 1956, her bow was removed and shipped in one piece across Hampton Roads and grafted onto Wisconsin, which had collided with the destroyer Eaton. In 1958, the engines installed on Kentucky were salvaged and installed on the s and . Ultimately, what remained of the hulk was sold for scrap on 31 October 1958. == Notes ==