Anchŏn-class battleship
 | This article is incomplete because it is pending further input from participants, or it is a work-in-progress by one author. Please comment on this article's talk page to share your input, comments and questions. Note: To contribute to this article, you may need to seek help from the author(s) of this page. |
 Haeju, Anchŏn's sole sister ship, as she appeared upon commissioning.
| |
| Class overview | |
|---|---|
| Name: | Anchŏn class |
| Builders: |
|
| Operators: | Greater Menghean Empire |
| Preceded by: | Songrimsŏng-class battleship |
| Succeeded by: | Chŏngdo-class battleship |
| Built: | 1919–1923 |
| In service: | 1922–1945 |
| Planned: | 2 |
| Completed: | 2 |
| Lost: | 2 |
| General characteristics (as built) | |
| Type: | Dreadnought battleship |
| Displacement: | |
| Length: |
|
| Beam: | 30.2 m |
| Draft: |
|
| Installed power: |
64,000 shp 4 steam turbines 20 water-tube boilers |
| Propulsion: | 4 shafts |
| Speed: | 24.3 knots |
| Range: | 5,000 km at 14 knots |
| Complement: | 1,324 |
| Armament: |
|
| Armor: |
|
| General characteristics (1938) | |
| Displacement: | 37,612 long tons full load |
| Length: |
213.2 m (waterline) 216.3 m (overall) |
| Beam: | 30.2 m |
| Draft: |
9.75 m (normal) 10.01 m (full load) |
| Installed power: |
80,000 shp 4 steam turbines 10 water-tube boilers |
| Propulsion: | 4 shafts |
| Speed: | 25.7 knots |
| Range: | 6,000 kilometers at 14 knots |
| Complement: | 1,976 |
| Armament: |
|
| Armor: | Turret face: 400mm |
| Aircraft carried: | 2 × floatplane |
| Aviation facilities: |
2 × catapult 1 × recovery crane |
The Anchŏn-class battleships (Menghean: 안천급 전함 / 安川級戰艦, Anchŏn-gŭb jŏnham), known under the Stuart-Lavender transliteration system as the Ahn Tsohn class, were a pair of battleships built in the Federative Republic of Menghe during the late 1910s and early 1920s. Among the battleships retained by Menghe under the Selkiö Naval Treaty, they underwent extensive reconstruction in the early 1930s to improve their combat capabilities. The changes included new engines, a rebuilt superstructure, and improved turrets, though the main armament of eight 40cm naval guns remained the same.
At the outbreak of the Pan-Septentrion War in 1935, the Anchŏn and her sister ship Haeju made up the Imperial Menghean Navy's Second Battleship Division. They were present at the Battle of San Ramon Bay, but first fired their guns at another surface ship during the Battle of the Portcullia Strait. Anchŏn and Haeju survived the battle, but both sustained heavy damage after drawing fire from most of Task Force Q, and they were under repair until early 1939. The ships saw little naval combat from 1940 onward, serving as part of the Imperial Menghean Navy's fleet in being. Haeju sank in shallow water near the city of Sunju and was converted to an anti-aircraft platform, while Anchŏn was sunk by a submarine near the city of Wihae, both in 1945.
Development
At the end of the War of the Sienese Succession, Menghe had one Songrimsŏng-class battleship in operation and a second nearing completion, both of them domestically built by Menghean shipyards. While the Songrimsŏngs were generally comparable with foreign battleships, they seemed at risk of falling behind a new post-war generation of battleships with larger guns and thicker belt and deck armor. In particular, the Menghean government worried about reports that Dayashina was working on a new type of battleship armed with 16-inch guns, which proved to be the Nagato class. Because Dayashina was Menghe's primary rival at the time, this spurred the development of a battleship class that could match this new threat.
The first proposal, designated J-1g, consisted of a Songrimsŏng hull with the triple 354mm turrets replaced by twin 400mm mounts. No other major changes were planned, and the design was largely preliminary. An improved design, J-1n, increased the main belt from 300 to 350mm, the deck armor from 75 to 100mm, and the torpedo bulkhead protection from mild steel to a 50mm structural hardened plate, compensating for these changes with a slightly deeper hull. THe boilers and turbines would also be replaced with newer models, yielding an estimated one-knot increase in top speed. This design would have retained the restricted firing arcs of the Songrimsŏng class, only able to fire one turret directly forward or astern.
A hybrid proposal, J-2g, attempted to improve on this issue with a new configuration. This resembled the final Anchŏn design, with two superfiring turrets forward, but the two aft turrets were both on the main deck in a non-superfiring arrangement. Top speed was increased substantially to 26 knots, rumored to be the top speed of the Dayashinese draft design, and armor protection followed the same standard set by J-1n.
The third proposal, J-3g, was arranged like the Daegok-class battlecruisers, with two superfiring turrets forward and another superfiring pair aft. J-3n, a revision of this design, reduced the size of the forward armor belt and removed one pair of amidships casemates in a bid to reduce structural loads on the hull. Top speed was kept at 26 knots. The additional weight of the raised barbette contributed to a 1,000-ton increase in displacement, and, in scale tests, a reduction in steadiness.
One shared feature of the J-2 and J-3 design groups is that they relocated the casemate guns one deck higher, putting them within the superstructure rather than on the hull sides. This was a contentious decision at the time; on four previous Menghean capital ship classes, the designers had insisted that the casemate loading areas be enclosed by the ship's upper armor belt, to prevent damage from medium-caliber weapons carried by the cruisers and destroyers that these guns were likely to engage. Experience with the Baekjin-class battlecruisers, however, had indicated that the low, open casemates were easily flushed out by water and spray, making them uncomfortable and inaccurate in heavy seas. Raising them by one deck, though reducing their armor protection, would increase their accuracy and consistency. The casemate design was also modified, with full wraparound armor (gunners entered by crawling underneath) to remove the pronounced side gaps seen on the Daegok and Songrimsŏng classes.
A number of other proposals were also considered at this stage, including one design with triple turrets. But with the Gyŏngsan Naval Yard on track to open its new slipway for construction in early 1918, the Navy leadership selected J-3n, the most mature and balanced design, for construction. The keel of the first ship was laid down on 1 February that year; the second would have to be postponed until 1919, as Parliament did not allocate enough funds for construction on both to begin in the same year.
During construction work on the first ship, to be named Anchŏn, reports from naval combat during the War of the Sienese Succession indicated that engagement angles were widening, meaning that plunging fire was a greater concern. The original armor belt extended less than half a meter below the minimum-load waterline, raising concerns that a shell impacting the water at an angle in front of the ship could pass below the armor and detonate within the torpedo protection. In response, the designers added a 70-cm strake of 300mm armor at the base of the main belt. This also caused the ship to sit somewhat lower in the water, further extending the belt (and machinery spaces) below the waterline. The armor deck, already 100mm thick, was not modified. This modification was designated J-3d.
Description
| This article is incomplete because it is pending further input from participants, or it is a work-in-progress by one author. Please comment on this article's talk page to share your input, comments and questions. Note: To contribute to this article, you may need to seek help from the author(s) of this page. |
In terms of their basic configuration, the Anchŏn and her sister ship were similar to the Dayashinese Nagato-class battleships or the Columbian Colorado-class battleships. Their main armament consisted of eight 40cm guns arranged in four superfiring two-gun turrets, and their full-load displacement came in at a little under 37,000 metric tonnes. Though relatively slow compared to the fast battleships that would follow, they had respectable performance, and fairly strong armor and torpedo protection.
Armament
<imgur thumb="yes" w="500" comment="The battleship Haeju as she appeared after her first round of refits, during the Battle of the Portcullia Strait.">MGC2j44.png</imgur> The main guns on the Anchŏn and Haeju were designated Type 16 40cm L/45. They used an Elswick-style 3-motion short-arm breech, and were reloaded at a fixed elevation of 5 degrees, meaning that the rate of fire was lower at high gun elevations; the "optimal" firing cycle at 5 degrees was reportedly 22 seconds. Elevation on the first-generation turrets ranged from -5 to +30 degrees, with maximum elevation increasing to 42.4 degrees after mid-life refits. Range and penetration values for the Type 33 Armor-Piercing shell used throughout the Pan-Septentrion War are as follows:
| Elevation | Range | Striking velocity | Angle of fall | Penetration (side) | Penetration (deck) | Time of Flight |
|---|---|---|---|---|---|---|
| 0.5 degrees | 850 m | 755 m/s | 0.5 degrees | 742 mm | -- | 1.3 seconds |
| 5 degrees | 9,100 m | 582 m/s | 6.0 degrees | 550 mm | -- | 13.6 seconds |
| 10 degrees | 15,200 m | 488 m/s | 13.5 degrees | 448 mm | 48 mm | 25.8 seconds |
| 15 degrees | 20,400 m | 442 m/s | 22.4 degrees | 402 mm | 98 mm | 36.2 seconds |
| 20 degrees | 24,900 m | 426 m/s | 30.5 degrees | 342 mm | 129 mm | 45.8 seconds |
| 25 degrees | 28,100 m | 419 m/s | 38.4 degrees | 302 mm | 151 mm | 58.2 seconds |
| 30 degrees | 30,800 m | 423 m/s | 44.5 degrees | 261 mm | 204 mm | 67.9 seconds |
| 42.4 degrees | 36,600 m | 457 m/s | 54.8 degrees | 198 mm | 271 mm | 92.5 seconds |
| 46.5 degrees* | 38,000 m | 460 m/s | 58.2 degrees | 176 mm | 302 mm | 96.7 seconds |
*Maximum elevation on coastal batteries using the gun.
Magazines for the main guns carried 110 shells and 440 quarter-charges per gun, or 880 rounds in total. The shell cage for lifting ammunition carried four stacked charges side-by-side with one shell, allowing easy ramming in two motions. The guns were mounted separately, and could be loaded, elevated, and fired independently of one another.
During major refits in 1932 and 1933, the ships were equipped with new main battery turrets which were essentially scaled-down versions of the turrets on the Chŏngdo-class battleships. The larger firing ports and deeper turret floors allowed an increased maximum elevation of 42.4 degrees, extending the theoretical maximum range by 6,000 meters. They also added new protection within the turret, with double-layered bulkheads between the individual gun compartments and between the upper turret and the ammunition handling room below. These were intended to reduce the extent of the damage if the turret suffered a penetrating hit, or if a gun misfired. The turrets' frontal armor was increased to 400mm, and the turret shape was revised to leave the sides less vulnerable to angled fire. Other changes included the installation of larger co-incidence rangefinders in the turret rear and the addition of saluting guns over the main guns.
The secondary armament consisted of eighteen Type 11 15cm L/40 breech-loading guns in casemate mounts, nine per side. These were the same secondary gun type used on the preceding Songrimsŏng-class battleships. They had a maximum range of 18,000 meters in their initial mounts, and a maximum practical rate of fire of about 5 rounds per minute. During mid-life refits, the mounts were replaced with new Type 30 L/50 guns in revised casemates which allowed a higher elevation, increasing the secondary battery's effective range.
Anti-aircraft armament initially consisted of four 7.5cm high-angle guns and eight Vickers machine guns, but over the course of the ships' service lives it was steadily increased to meet the increasing threat from carrier aircraft. Refits in the early 1930s converted the anti-aircraft armament to eight 10cm Type 29 anti-air guns and ten 12.5mm water-cooled machine guns; in 1937, the designers added six single 37.5mm Type 37 anti-aircraft guns and relocated some of the machine-guns, bringing the total to twelve. After the Battle of the Portcullia Strait, the Imperial Menghean Navy used the ships' repair period to install greatly improved flak defenses, with eight twin 10cm guns in mounts with improved traverse and elevation. The number of 37.5mm and 20mm autocannons steadily increased over the course of the ships' lifetimes, especially after the Haeju was converted to a coastal AA defense platform.
The Anchŏn-class battleships were built with underwater 550mm torpedo tubes, each of which came with three torpedo reloads. Two tubes faced each broadside; there were no bow or aft tubes. The torpedo magazines and handling rooms were included within the ship's armored citadel, but they did interrupt the layered structure of the ships' torpedo protection. They were removed during refits.
Protection
Anchŏn was the first Menghean battleship to incorporate "all-or-nothing" armor protection on her hull, with a 350mm main belt running around the magazines, turbines, and boilers but no waterline armor protection forward or aft. The main belt did, however, wrap around the forward and aft ends of the citadel with transverse bulkheads. A 150mm upper belt above the main belt provided additional protection. Deck armor consisted of a 100mm "turtle-back" armored deck over the citadel and a 50mm armored deck one level above it; the spacing was intended to de-cap armor-piercing shells or detonate them prematurely. A 25mm, later 75mm, armored plate over the quarterdeck provided some protection to the rudder and steering equipment. This armor configuration was generous for the time, and it would allow the Anchŏn and Haeju to remain afloat despite suffering numerous direct hits at the Battle of the Portcullia Strait.
Armor on the ship's armament was comparable. The main battery barbettes had armor plating 350mm thick, and the turret faces were 350mm thick, later increased to 400mm. Turret armor was 150mm thick on the sides and 100mm thick on the roof and rear. The secondary battery barbettes were 125 millimeters thick. The best-protected area was the forward conning tower, at 400 millimeters thick.
Unlike the Songrimsŏngs and their predecessors, all of which had relied on torpedo nets for defense in port and would later have to be refitted with anti-torpedo bulges, the Anchŏn-class battleships were built from the keel up with internal torpedo bulkheads to limit torpedo damage. These bulkheads, 50 millimeters thick, ran the full length of the armored citadel, covering the magazines, boilers, and turbines. Outside of the bulkheads were alternating compartments containing air and fuel oil to absorb the pressure wave from a torpedo's detonation. Individual rooms and compartments in the bow and stern could also be sealed with watertight doors to contain flooding.
Propulsion
As built, the Anchŏn and Haeju were powered by four 16,000-horsepower (11,900 kW) steam turbines paired with twenty water-tube boilers. These burned a mixture of coal and oil, with the former used for cruising and the later sprayed onto the fuel when higher output was necessary. As on many other battleships of the time, smoke from the forward funnel frequently blew onto the foremast's observation deck before refits. At full steam with a normal combat load, the ships could reach a top speed of 24.3 knots.
During comprehensive refits in 1932 and 1933, the inefficient and outdated coal-oil boilers were replaced with twelve oil-fired boilers trunked into a single funnel. The turbines were also upgraded, allowing a maximum combined output of 80,000 horsepower across four shafts. Due to the increased mass added during refits, the ships sat lower in the water with this configuration, and top speed only increased to 25.7 knots. Range increased only modestly, to 6,000 nautical miles at 14 knots.
Aircraft
As part of their mid-life refits, each ship was fitted with two aircraft catapults, each carrying a single floatplane. These were located on either side of the ship on the aft deck, forward of the #3 turrets. A single crane aft of the catapults could be used to recover planes once they taxied to one side of the ship. Menghean designers initially favored this type of amidships catapult, as it allowed two aircraft to be carried yet it did not interrupt the firing arcs of the aft turrets. This configuration did, however, reduce the available deck space for anti-aircraft guns.
After the Battle of the Portcullia Strait demonstrated the importance of carrier aircraft in attacks on large surface vessels, the Imperial Menghean Navy altered the ships' design during their repair period, removing the amidships catapults and replacing them with a single catapult arm on the quarterdeck. Two reconnaissance aircraft could be carried: one on the catapult, and one on the quarterdeck adjacent to it.
Ships in class
A total of two Anchŏn-class battleships were produced. In keeping with Menghean nomenclature tradition, they were named after Menghean cities - specifically, the cities of Anchŏn and Haeju, both located along the eastern coast. Collectively, these two warships formed the First Battleship Division, and they generally operated together to facilitate maintenance and logistics.
During the early interwar period, the First Battleship Division patrolled the eastern coast of Menghe, part of a buffer against Dayashina. After war with Sylva broke out in 1935, they took part in the bombardment of Altagracia, and patrolled the southern coast as a deterrent against the Sylvan battleships stationed in Maracaibo. In 1938, the First Battleship Division joined the rest of the Combined Battle Fleet to inflict a decisive defeat on the Tyrannian Royal Navy at the Battle of the Portcullia Strait, though both ships sustained heavy damage and underwent major reconstruction in late 1938 and early 1939.
Anchŏn
<imgur thumb="yes" w="500" comment="The battleship Anchŏn in 1940, after her major repairs and refits. Note the relocated floatplane catapult and the increased anti-aircraft armament.">g90Op5V.png</imgur> Laid down on 3 May 1919 at the Gyŏngsan Naval Yard, the Anchŏn (Menghean: 안천/安川) was commissioned on 19 June 1922. She was the first ship of the class. Under the Stuart-Lavender romanization system in Western use at the time, she was known as Ahn Tsohn.
Haeju
Haeju (해주/海州), known to the Western Allies as Hai Chu, was laid down on 21 June 1920 at the Kimhae Naval Yard and commissioned on 30 September 1923. She was identical in construction to her sister ship. Haeju became famous for firing the shell that detonated the magazine of HMS Indomitable at the Battle of the Portcullia Strait, sinking the latter ship in a matter of minutes. Like her sister ship, Haeju was significantly rebuilt after the battle, though she ultimately mounted a different seaplane assembly.
On the night of June 4-5, 1944, when both battleships were anchored in Sunju Harbor, Columbian carrier aircraft attacked them in port, part of a daring raid along the south Menghean coast. The Haeju sustained multiple torpedo hits and began taking on water. Fearful that the ship would sink, Captain Ha steered her toward the shallow coastal waters near the mouth of the Chŏllo river, where she ran aground in the early hours of the morning. The ship settled on the soft mud deposited by the river, and the entirety of her weather deck remained above the waterline, though her aft freeboard was reduced to less than a meter. The Imperial Menghean Navy determined that it was too costly and too dangerous to mount a salvage operation, and instead the stationary wreck of the Haeju was converted into an anti-aircraft platform through the addition of more medium-caliber AA guns. Her umbrella of AA fire provided some protection for the light vessel docks and repair yards nearby, and she remained operational for several months despite repeated attacks from Allied dive-bombers and strategic bombers. On August 14th, bombs from a dive-bomber raid set off a fire on her fore deck, which gradually spread to the medium-caliber AA magazines; when the fire was extinguished the following day, the high-caliber AA guns were damaged beyond easy repair, and only small- and medium-caliber AA guns could be re-mounted. The wreck was broken up in 1946.
See also