Chŏngdo-class battleship
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| <imgur w="300px">7z3U88j.png</imgur> Chŏngdo in 1926, as she appeared when commissioned.
| |
| Class overview | |
|---|---|
| Name: | Chŏngdo class |
| Builders: |
list error: <br /> list (help) |
| Operators: | Greater Menghean Empire |
| Preceded by: | Anchŏn-class battleship |
| Succeeded by: |
list error: <br /> list (help) Junggyŏng-class battleship (planned) Hyangchun-class battleship (actual) |
| Built: | 1922–1927 |
| In service: | 1926–1944 |
| Planned: | 2 |
| Completed: | 2 |
| Lost: | 2 |
| General characteristics (as built) | |
| Type: | Dreadnought battleship |
| Displacement: |
list error: <br /> list (help) |
| Length: |
list error: <br /> list (help) 272.3 m (waterline) 281.4 m (overall) |
| Beam: | 30.8 m |
| Draft: | 10.23 m full load |
| Installed power: |
160,000 shp 4 steam turbines 12 water-tube boilers |
| Propulsion: | 4 shafts |
| Speed: | 30.5 knots |
| Range: | 6,000 km at 14 knots |
| Complement: | 1,624 (1,657 as flagship) |
| Armament: |
list error: <br /> list (help) |
| Armor: |
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The Chŏngdo-class battleships (Menghean: 청도급 전함 / 青島級戰艦, Chŏngdo-gŭb Jŏnham), sometimes referred to as Chŏngdo-class battlecruisers, were a pair of fast battleships built during the early 1920s. With an overall length of 281 meters and a full-load displacement of 46,000 tons, they were at the time of their completion the largest warships built in Menghe and among the largest in Septentrion. Some of their successors, including the planned Junggyŏng and half-completed Insŏng classes, would have been larger, but the Chŏngdos were the largest Menghean warships to see service until the commissioning of the nuclear-powered aircraft carrier Sibiwŏl Hyŏgmyŏng in 2006.
During the Pan-Septentrion War, the Chŏngdo and her sister ship Sunju constituted the Second Battleship Division of the Imperial Menghean Navy, alternating as fleet flagship. They played a pivotal role in the Battle of the Portcullia Strait, luring Task Force Q toward the main Menghean battle line and pursuing it back toward Khalistan. While Menghe enjoyed naval superiority in the east, they alternated as commerce raiders in the Eastern Helian Ocean, occasionally returning to the Maverican coast to support shore bombardment missions.
Classification
Some ambiguity exists as to whether the Chŏngdo and Sunju should be considered battleships or battlecruisers. With a top speed of 30 knots, they were as fast as the Dayashinese Amagi-class battlecruisers and over five knots faster than their predecessors. But unlike a strict battlecruiser design, they did not sacrifice armor protection in order to achieve this speed. In terms of both belt and deck armor, they were comparable in protection to contemporary battleships. Anglia and Lechernt applied the "battlecruiser" designation to its own Admiral-class warships, which had similar specifications.
Menghean language sources, including the official Menghean Navy ship register, described the Chŏngdo-class as gosok jŏnham (고속 전함 / 高速戰艦), meaning "fast battleships" or "high-speed battleships." The Menghean Navy applied this term both to the Daegok-class battlecruisers, which likewise achieved high speed at the cost of added displacement rather than reduced protection; but it also applied it to the Baekjin-class battlecruisers, which carried substantially lighter armor and armament. Official Menghean Navy terminology of the early 20th century did not use sunyang jŏnham, or "battlecruiser," even when referring to foreign warships which did sacrifice armor; the term existed only in informal circles, and only gained wider use after the war.
During the interwar period and the Pan-Septentrion War, both "battleship" and "battlecruiser" appeared in Anglian-language records, with the Royal Navy calling them the latter.
Background
The War of the Sienese Succession was still ongoing in the late 1910s, but the Menghean Navy's primary focus remained on neighboring Dayashina, which had aspirations to expand its colonial influence on the Hemithean continent. In 1911, Menghe had ordered the two Daegok-class battlecruisers from Anglia and Lechernt, but with the outbreak of the WSS the Anglian government had confiscated them for use by the Royal Navy. Anglian diplomats had promised that both ships would be returned to Menghe upon the war's end, but Menghean military planners were unsure whether to trust this promise, or whether the two ships would survive the rest of the conflict.
Faced with this uncertainty, in 1917 the Ministry of the Navy solicited preliminary design studies for a battlecruiser class that would be built domestically. These designs were given the prefix "GG," designating a domestic high-speed battleship. The requirements called for the same protection and armament as the Daegok class, but a higher top speed, as the Dayashinese Kongo class were faster than anticipated at the time of the Daegoks' development. The Navy's tentative plan was to order two of these ships in 1919, such that even if the war ended and the Daegoks were returned, Menghe would have four 14"-armed battlecruisers against Dayashina's four Kongos.
During development, evaluators raised concerns about whether the 14"/50 naval gun was adequate for the proposed design. Menghean intelligence reported that the Nagato-class battleships under construction in Dayashina would carry a 15-inch main belt and 4 inches of deck armor, and future classes would likely carry more. Firing trials with the 14"/50 gun for the Songrimsŏng-class battleships also revealed that its accuracy and barrel life were both poor. In response, the Navy leadership revised the requirement, now requesting that the main battery use the 40cm L/45 Type 16 gun ordered for the Anchŏn-class battleships. The Navy also increased the requested level of deck protection.
To meet these requirements, the submitted designs ballooned in size. Plan 11g, the first entry to receive an official plan designation, sported a 4x2 40cm main battery, a 30cm belt, and 10cm of cumulative deck armor, as well as an impressive 32.5-knot speed on a projected 200,000-shp powerplant. The designers claimed an even higher 34-knot top speed at light displacement. Plan 11g paid for these improvements in size, displacing 45,900 tonnes fully loaded, and in magazine space, with only 90 rounds per main battery gun. The Navy took this design seriously enough to invest in refining and improving it, resulting in Plan 11n.
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In the resulting "40-centimeter Navy" construction programme, the Navy leadership called for the construction of four large, fast battleships, on par with the latest international designs, each one sporting ten 40-centimeter guns. These would be supplemented, in future growth, by four successor battleships with heavier armor and a larger main battery - what would later become the Junggyŏng designs. The Anchŏn class battleships would be kept in service, and the Songrimsŏngs and all earlier battleships moved to reserve status in the long run.
The Federal Assembly balked at the expense of this plan; even the construction of the Songrimsŏng and Anchŏn battleship classes, motivated by wartime threat, had severely drained the national treasury. Two fast battleships were approved in the 1920 budget, with a provision that future construction could only go ahead if the naval arms race in rival countries demanded it. Construction was delayed by a year, as the battleship slipways at the Kimhae and Gyŏngsan Naval Yards had to be extended by 80 meters to accommodate the new hulls, and the keels of both ships were laid down in 1922.
During the signing of the Selkiö Naval Treaty, Menghe successfully negotiated to keep both Chŏngdo-class battleships, which had already been launched but were still being fitted out.
Design
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The Chŏngdo-class battleships were 27% longer than their immediate predecessors, the Anchŏn-class, and only slightly wider. They were, at the time of their completion, the longest battleships in the world, though still lighter in displacement than the largest warships retained under the treaty. This extended length allowed them to mount an additional twin 40cm turret, resulting in an AB + XYZ layout similar to that on the Dayashinese Amagi-class battlecruisers. A notable difference between the Menghean and Dayashinese designs was that the superstructure ended at the X rather than the Y turret, allowing the space between them to be used for a boat deck with vents to the turbine rooms.
Armament
The main battery of the Chŏngdo-class battleships consisted of ten 40cm L/50 Type 16 naval gun. This was the same type used on the preceding Anchŏn-class battleships, and it shared the same range and penetration tables. The turrets themselves, however, were of a different design, with better internal spacing and a maximum gun elevation of 42.4 degrees. Turrets of the same design were later refitted to the Anchŏn and Haeju during their mid-life refits. In addition to their improved internal characteristics, the new turrets also had thicker frontal armor, and internal flash-proof plates between the gun compartments to contain the damage from a penetration or misfire.
Main battery ammunition capacity consisted of 120 shells per gun, in magazines underneath each turret. Various sources give a maximum firing cycle time of 30-32 seconds, though as reloading was carried out at a fixed +5 degree elevation, the actual rate of fire could be lower if the guns had to elevate and depress between shots.
The secondary battery consisted of sixteen 150mm L/40 Type 11 naval guns, eight on each broadside. As the shorter superstructure section resulted in less space per side, half of these guns were placed in deck mounts with gun shields, and the other half in conventional casemates beneath them. The deck mounts were in fact the same type used on the Ichŏn-class cruisers a few years later. Although they were less well-protected than the casemate guns, they could reach a higher maximum elevation, and thus a greater range. As the 150mm magazines were located underneath the B and X turret magazines, shells and charges were passed to the secondary battery along a conveyor assembly which ran on top of the splinter deck between the magazine hoists and the gun hoists.
Initial anti-aircraft armament was adequate for the time, with four 7.5cm high-angle guns per broadside on platforms flanking the funnels. These were originally of Rajian design, and were standard on Menghean capital ships of the post-WSS period. Vickers guns on single mounts provided close-range AA defense. During subsequent interwar and wartime refits, both ships would receive steady improvements to anti-aircraft firepower, including the replacement of the upper-level secondary guns with twin 10cm AA mounts.
As designed, both ships would have featured below-water 55cm torpedo tubes, four on each broadside. This feature was omitted in the modified design, in an effort to reduce the armored area outside the citadel. It also reflected the Menghean Navy's increased attention to long-range combat.
Protection
<imgur thumb="yes" w="300" comment="Transverse cross-section of the Chŏngdo through her #2 funnel, showing armor thicknesses in millimeters around the boiler spaces. Note also the oil tanks (grey) and shell hoists.">yQYF1wk.png</imgur> Although they were much faster than their predecessors, the Chŏngdo class had comparable protection to many contemporary battleships, with the same main belt thickness as the Songrimsŏng class and similar deck protection to the Anchŏn class. During construction, the deck armor was substantially improved, and during refits in the 1930s it was improved again. As on the Anchŏn-class, protection followed the "all-or-nothing" principle, with armor concentrated around the magazines, boiler rooms, and machinery spaces but no waterline belt around the bow or stern. This, along with the improved deck protection, correctly anticipated the increasing ranges at which naval battles would be fought in the relatively open waters of the South Menghe Sea and East Helian Ocean.
The main armor belt was 300 millimeters thick around the boiler and machinery spaces, tapering to 220 millimeters underneath the A and Z barbettes, and angled outward at 9 degrees. At either end, it terminated with a lengthwise bulkhead, 250 millimeters thick at the forward end and 350 millimeters thick at the aft end. This, too, reflected the designers' focus on "retreating engagements" with enemy fleets, a strategy which Admiral Cho Sŭng-chŏl would employ at the Battle of the Portcullia Strait. A 75-millimeter upper belt provided some additional protection for the ship's internal spaces, mostly by helping slow down armor-piercing rounds descending toward the deck. Notably, with the exception of the 350-millimeter aft bulkhead, this armor scheme was thinner than that on the Anchŏn-class battleships. At ranges of below 28 kilometers, a 16-inch shell could penetrate the main belt, though the designers anticipated that the 150mm angled deck section would add enough protection to reduce the 16-inch protected range to under 15 kilometers.
Horizontal protection was layered, a configuration which the Menghean Navy considered more effective for breaking up high-caliber shells. An upper 25mm plate ran the full length of the citadel, forming the floor of the third deck; its purpose was to break the soft cap of armor-piercing shells, making them less effective when they struck the main armor deck below. This deck was 100 millimeters thick in its horizontal areas, widening to 150 millimeters at the angled "turtleback" edges. In addition to adding to the effective horizontal armor thickness, these sections formed a triangular gap which could contain flooding from holes at or just above the waterline. Over the magazines and turbines, the main armor deck thinned to 75 millimeters, but a 25 millimeter splinter deck below it was designed to stop shell fragments and spalling from damaging the fragile systems below. The only deck armor outside the citadel was a 75mm plate extending aft, with 150mm angled sides over the steering equipment.
Torpedo protection consisted of four layered watertight compartments on either side, two of which were filled with fuel to dampen the force of an underwater blast. Once empty, the individual fuel tanks could be filled with seawater to maintain constant levels of protection. The outer bulkhead and the two innermost ones were covered by 25-millimeter armor plates, providing further protection. While impressive in length, depth, and complexity, this torpedo protection scheme had the flaw of connecting the top of the torpedo bulkhead to the base of the horizontal splinter protection, below the base of the main armor belt. In combat, it was found that this layout concentrated the force from torpedo explosions into the contained area rather than diverting it outside the ship. Both ships suffered serious torpedo damage at the Battle of Frederick's Point in 1941, revealing to the designers the problems with the layered bulkhead arrangement.
Propulsion
The powerplant of the Chŏngdo class consisted of four geared steam turbines, each driving a single shaft. These were paired into two turbine rooms, one forward and one aft of the X turret and its magazines. Steam for the turbines came from twelve three-drum boilers, arranged in four rows of three with two under each funnel. In contrast to the Anchŏn and Songrimsŏng classes, which burned a mixture of coal and oil, the Chŏngdo-class battleships were entirely oil-fueled, allowing the use of more efficient machinery and fuel storage spaces. At full speed and with a regular combat load, they could manage 30.5 knots.
Notably, unlike other Menghean large warships of the time, the Chŏngdos did not have internal lengthwise bulkheads separating their individual boilers, part of an effort to save space and weight while maximizing output; intended to contain flooding, these bulkheads were found to create serious listing problems after a torpedo strike by flooding one boiler space but not the one on the other side.
In an effort to achieve even higher speeds from a given engine output, the designers opted for a long, slender hull; in fact, Chŏngdo was the longest capital ship in the world upon her completion. They also incorporated a bulbous bow design to reduce drag, which also allowed for a stronger keel under the foredeck. The heavily angled clipper bow allowed increased seaworthiness in rough seas, and contributed to the ships' distinctive appearance.
Mid-life refits
Both ships became eligible for comprehensive mid-life refits in 1933, as approved under the Nine-Power Naval Treaty. The original reconstruction plan called for a new 200,000 shp powerplant, which would increase top speed to 32 knots - equal to the IMN's projection of the Rajian Roteva-class battlecruisers' speed after their refits. Provisional plans for the secondary armament involved removing the deck-mounted 150mm guns and above-deck 75mm AA guns and replacing them with sixteen 100mm L/40 dual-purpose guns in eight twin mounts, four on each side of the funnels.
After both ships had been taken into drydock, news of naval construction elsewhere led the IMN to revise the Chŏngdo reconstruction plans to include a substantial thickening of the main armor deck to improve protection from plunging fire. Design work on what would become the Hyangchun-class battleships had also produced a dual-purpose 130mm secondary turret, leading to discussion of whether the Chŏngdos should be modified to incorporate such a weapon or whether it would bring them over their 45,000-ton standard displacement limit. The Hasŏlsan-class cruisers, already under construction, were projected to far exceed their official tonnage, and growing international tensions were leading the new IMN leadership to favor more ambitious designs. Preparations for a declaration of war against Sylva in 1935 further complicated the reconstruction schedule, with some Navy officials arguing that the ships should be taken out of refits faster to guard against the possibility that other Great Powers would intervene against Menghe. In the end, none did.
In June 1935, Dayashina formally withdrew from the Eight-Power Naval Treaty to begin work on its Yamato-class battleships, triggering a series of rival defections that left the treaty in tatters. As Menghean engineers no longer faced limits on the amount of tonnage the ships could displace, they launched a final round of changes to the Chŏngdo hulls, adding the 130mm dual-purpose battery and improving the fire-control systems. Mathematical projections suggested that the post-refit ships would sit close to a full meter lower in the water due to the added weight, creating problems for seaworthiness, so the ships were also given anti-torpedo bulges to improve their flotation and stability. These had the added affect of further improving their underwater protection, a change which they would need in combat.
Chŏngdo was released from drydock in December 1935, and Sunju in March 1936, freeing up space for the laying of the Hyangchun and Yŏng'an. Work on fitting-out continued well into 1936, with both ships approved for active service before the end of the year. Neither would see combat until 1938.
Armament
During reconstruction, the main guns on the Chŏngdo and Sunju were removed from their mounts and heavily reworked at the foundry for improved performance. The new weapons, designated 400mm L/55 Type 30, they had an increased chamber volume to allow for larger propellant charges, more durable carbon steel liners with uniform 1 in 25 rifling, and more durable liner locking rings. These changes, also applied to the Anchŏn-class battleships, allowed the guns to fire the heavier Type 34 400mm armor-piercing round to a higher muzzle velocity with a greater range. The same ammunition type would later be used on the Hyangchun-class battleships.
Internally, the turret floors were lowered to allow for a higher maximum elevation of 44 degrees, as opposed to 35 degrees on the original turrets. Steel anti-flash barriers between the loading rooms were installed to prevent misfires or penetrations on one side of the turret from spreading to the other gun, though they were only 10mm thick with no spacing in between, and Sunju would lose one turret to a penetrating barbette hit at Portcullia. The shell and ammunition hoists were also reworked to improve flash separation between the loading spaces, handling rooms, and magazines. Finally, main gun fire control was improved through the installation of new rangefinders in the turret rear sections, as well as improved fire-control towers on the main superstructure with direct mechanical connections to plotting rooms within the citadel.
More radical changes were applied to the secondary armament. The entire casemate and deck gun structure was removed during the tear-down to access the boilers and rebuilt as a level deck with eight twin dual-purpose mounts for the 130mm L/55 Type 32 naval gun. These were not superfiring, but the forward and aft pairs were offset slightly inboard, allowing their outboard partners to fire almost directly ahead aside of them. In practice it was discouraged to fire the secondary guns at less than 15 degrees from directly forward or astern. The new ammunition used the same magazines, lifts, and conveyors as the 150mm shells that came before, though the hoists were entirely reworked to feed directly into the rotating turrets via a central stalk.
Though some Navy officials initially contended that the dual-purpose guns would hamper anti-surface effectiveness, the Type 32 gun proved to be a highly effective weapon in trials and combat. Its range and penetration exceeded those of the 150mm guns it replaced, and it offered more consistent accuracy with a higher rate of fire. Maximum elevation was 80 degrees and powered traverse rate was 15 degrees per second, both high enough to effectively track aircraft even late in the war. Each pair of staggered guns was directed from a dedicated fire-control tower on the superstructure but could also be aimed manually.
When the ships were returned to service in 1936, their only other anti-aircraft armament consisted of fifteen single 12.5mm water-cooled machine guns distributed around the deck and superstructure. Combat experience against Sylvan aircraft had already proven these inadequate, but work on a new medium-range anti-air gun was still in progress, so the battleships went to sea with little in the way of short-range AA defense. This situation would change dramatically later in the war, as successive minor refits added more and more anti-air guns.
Protection
Though already strong at commissioning, the ships' armor scheme underwent a significant overhaul during reconstruction, mainly in order to improve immunity against plunging 16-inch fire. The thickness of the main armor deck was increased to 150 millimeters over the entire citadel, and the lower sides of the funnel uptakes were protected by 200 millimeter bulkheads in order to prevent shells from entering the boiler rooms at an angle. The 25mm upper de-capping plate was retained, as was the 25mm lower anti-spalling plate.
While the original armor deck had featured "turtleback" angled edges, on the rebuilt scheme the main armor deck was entirely flat, extending to the top of the belt. This change was apparently intended to eliminate the possibility that shells descending at moderate angles could fly above the belt and penetrate the angled turtleback section at a favorable angle. To compensate for the lost turtleback cover, the thickness of the main belt was increased to 350 mm, but close-range protection was still greatly reduced. To save weight, the upper belt was reduced to 50 millimeters. Interestingly, the 300mm turret barbettes were not modified, and the new turret sides were kept at 200 millimeters.
Surviving Menghean documents state that the revised armor scheme was immune to 16-inch shellfire at ranges of 21 to 29 kilometers, and 14-inch shellfire at ranges of 12 kilometers and above. These estimates were apparently based on mathematical calculations for the armor penetration of Menghean 400mm and 350mm shells at these ranges. Over the course of the Battle of the Portcullia Strait, where most fighting took place at between 18 and 24 kilometers, neither the Chŏngdo nor the Sunju suffered a penetrating hit to the main belt or deck, though the Sunju had two of her turrets knocked out of action. This was the only engagement in which either ship encountered battleship-caliber gunfire.
The new anti-torpedo bulges extended 1.9 meters outward from the side of the ship at their thickest point. They were entirely air-filled, to add buoyancy, and were divided internally into watertight compartments. In addition to adding depth, the new bulges were intended to correct for a problem identified in scale-model testing, whereby a torpedo could penetrate into the original armor scheme and explode below the belt, focusing its blast upward into a "corner" of bulkhead space rather than venting it outside the ship. In total, the new torpedo protection layer surrounding the boiler rooms was 6.5 meters thick and composed of five layers of watertight compartments, of which 2 to 3 were filled with fuel; three of the six bulkheads were covered in 25mm armor plate.
Propulsion
Other changes
A catapult carrying a single Donghae Type 36 reconnaissance floatplane was added to the roof of turret "X" on both ships. No other aircraft were carried, and there were no onboard hangar or repair facilities. Recovery was conducted by means of a pair of cranes, one per side, which also hoisted lifeboats from the boat deck into the water.
Operational history
Together, the fast battleships Chŏngdo and Sunju formed the Second Battleship Division, with Chŏngdo usually serving as flagship. Owing to their high speed - a full eight knots faster than the Songrimsŏng-class battleships before their engine upgrades - they operated somewhat independently of the First and Third Battleship Divisions in peacetime. The Navy anticipated at first that the Second Division could move rapidly to support either fleet in the event of an attack, or that it could sortie independently to repel a small battlecruiser force.
Kwon Chong-hoon's coup in 1927 and his replacement of the Navy leadership in the April 11th Incident, led the IMN to pivot toward a more aggressive outlook in the use of these two ships. Refits in the 1930s brought a modest extension of their range, allowing them to be used for commerce raiding and extending their endurance on long patrols. Although their refits were cut short due to the anticipation of war, both ships remained formidable capital ships at the outbreak of the Pan-Septentrion War.
Early service
When Menghe declared war on Sylva in 1935, the Chŏngdo and Sunju had recently been returned to operational service after their mid-life refits. They did not directly take part in the Fall of Altagracia, but they played a supporting role by venturing out into the South Menghe Sea with a group of escorts, including the light carrier Emil-si, in order to help intercept the Sylvan Flota Oriental if it attempted to relieve Altagracia's defenders. As the Flota Oriental remained in Puerto Alegre during the fall of Altagracia and later withdrew to Valencia, the two fast battleships did not see combat, and after the Flota Oriental withdrew they returned to Dongchŏn.
During the remainder of the early war, the Chŏngdo and Sunju supported the Menghean invasion of Innominada. They provided heavy bombardment prior to the landings around Puerto Alegre and Cartagena in 1936, and operated out of Las Playas for most of 1937. During this phase of the war, they became active in raids against Sylvan convoys bringing supplies to the garrison around Salvador, usually working some distance apart to maximize coverage while remaining close enough to support each other if the Flota Oriental attacked.
Admiral Cho Sŭng-chŏl, who took command of the Chŏngdo as his flagship in 1936, regarded her as an excellent vessel. She was the flagship of the Menghean Combined Fleet on all occasions in which it formed, and after 1938 Admiral Cho had her command facilities modified to better suit his needs.
Battle of the Portcullia Strait
The Second Battleship Division played a pivotal role in the Battle of the Portcullia Strait, which brought a temporary end to the Royal Navy's presence in the Hemithean theatre of the war. In the opening phase of the engagement, they served as bait for Task Force Q, sailing with a light escort force from Puerto Alegre to the Helian Ocean while the Royal Navy's battleships were docked in nearby Moradabad. After coming under fire, they lured Task Force Q toward the main Menghean battle line, which had gathered north of their position under the cover of darkness without the Royal Navy's knowledge. Victory at Portcullia, which ended with the sinking of one Tyrannian battleship and serious damage to the remaining three, granted Menghe naval superiority until the end of 1940, allowing the Axis to conduct amphibious landings in Khalistan later that year.
During the pursuit of the damaged Tyrannian capital ships at the end of the line battle, the Sunju suffered a direct hit to her bridge, causing the bulky tower to collapse forward over the superstructure. Ra Myŏng-jun, the captain, was killed, and both co-incidence rangefinders for the main guns were destroyed, but the backup navigation center in the armored conning tower remained intact and the surviving officers were able to steer Sunju out of formation and return her to port. Chŏngdo continued the pursuit for another ten minutes, then broke off the pursuit to avoid becoming too overextended.
Chŏngdo's Helian voyage
Both the Chŏngdo and the Sunju sustained damage at the Battle of the Portcullia Strait, but the Sunju's damage was more severe. In addition to the damage to her bridge, which would be completely rebuilt according to a new format, her "Y" turret had been jammed by a non-penetrating shell hit to the barbette, and she had suffered close to a dozen non-penetrating or non-critical hits elsewhere. She would remain in port under repair for over a year afterward, longer than HMS Warchild in the opposing fleet, and would emerge with a new secondary battery configuration incorporating the dual-purpose guns which had been planned during her mid-life refit.
During this time, the Chŏngdo, which returned from her repairs in October 1938, operated independently of her sister ship, supporting the Imperial Menghean Army's advance along the coast of Khalistan. While the Songrimsŏng and Daegok provided close support for forces on the west coast, the Chŏngdo ventured further afield, attempting on two occasions to finish the HMS Warchild.
In 1939, with the large cruiser Baekjin as her sole escort, Chŏngdo embarked on a prolonged commerce raiding mission in the Helian Ocean. Her voyage brought her as far as Kopanes, Ostland, where she refueled, took on supplies, and hosted an inspection by Ostlandian naval officers. In June, she sank a merchantman 120 kilometers off the coast of Sylva before withdrawing at speed, the furthest west any Menghean warship traveled during the war. Tyrannian and Rajian naval forces made repeated attempts to pursue her, but in the end she returned to Menghe of her own accord, as prolonged cruising had left her engines badly in need of an overhaul.
During her return voyage, the Chŏngdo encountered the Tyrannian convoy ON 54, which consisted of 44 freighters and 6 troopships escorted by 2 destroyers and 4 corvettes, all bound for Naseristan. The convoy, which was crossing the middle of the ocean, lacked aerial reconnaissance, and did not spot the Chŏngdo or its reconnaissance plane until the former was already within range. Unwilling to waste main battery ammunition, which was already running short, Captain Pak Hae-il closed the distance to 5,000 meters, overtaking the slow convoy from behind. The destroyers HMS Ardent and HMS Agile charged the oncoming ship, attempting to repel her with torpedo fire, but they came under withering gunfire from the Chŏngdo's main guns and dual-purpose battery. By the end of the engagement, the Royal Navy had lost both destroyers, two corvettes, and 45 of the 50 transport ships, including all six troop transports. As the convoy ships had continued to flee while under attack, Pak Hae-il had ordered the Chŏngdo to fire on them as well, prioritizing the troopships and oil tankers. Following the two corvettes' withdrawal, the surviving merchantmen surrendered; the Mengheans loaded the surviving civilians onto five freighters, took the soldiers and sailors on board as prisoners, and scuttled the remaining vessels with Chŏngdo's 150mm battery. Originally Captain Pak planned to take the five merchantmen converted to prison ships back to Menghe, but he later decided that their low speed and risk of mutiny posed a threat to Chŏngdo's escape, and after taking her own prize crews back aboard, he disabled their radio equipment and ordered them to make a northerly course to Liberty Island. For Tyran, this was the costliest convoy battle of the entire war, and it cemented Chŏngdo's reputation as a feared opponent.
Confrontations with the OSN
After her engine and armor repairs were completed, the Chŏngdo returned to combat-ready service in early September of 1940. A little over a month later, she joined Sunju in the Combined Fleet's offensive at the Battle of Swartzburg, once again with Admiral Cho Sŭng-chŏl on board. As the Maverican Navy was too weak to risk a direct confrontation, both fast battleships mainly performed shore bombardment operations against coastal fortifications on the surrounding islands.
After the Organized States entered the war, Columbian bombers and carrier-based strike aircraft attacked the Menghean fleet in retaliation, forcing the Chŏngdo and Sunju into a defensive posture. Both ships sustained only minor bomb damage, but Admiral Cho refused to withdraw until the landing force had been fully evacuated, risking his battleships in a defensive line that the OS Navy outnumbered. In the end, however, the Columbian surface attack never materialized, and Chŏngdo and Sunju covered the rear of the retreating troopship convoy.
The Organized States would have another opportunity to confront the Second Battleship Division at the Battle of Frederick's Point near Baumburg, Maverica in May 1941. On the 19th, the first day of the battle, the Menghean battleship formation came under sustained attack from Columbian carrier aircraft. Sunju suffered five torpedo hits, all on her port side, but her captain initially reported that the flooding was under control and remained in formation. By 1955 hours, however, personnel on other ships observed that she was sitting low in the water and beginning to list to port. Frantic damage-control efforts were unable to contain the flooding, which had spread into her boiler and turbine rooms, and even with belated counter-flooding on the starboard side, she capsized thirty minutes later. This came as a surprise to the IMN's officers, who considered the Chŏngdo-class battleships fairly advanced in their torpedo protection; yet as the Sunju sank over the course of two hours, with the loss of almost all of her damage-control personnel, it was unclear how or why she had flooded so quickly. The loss of one of the two largest battleships in the formation did not bode well for Menghean morale in the Baumburg offensive, and Admiral Cho himself was visibly shaken at seeing his flagship's sister capsize in the evening light.
During the night engagement which followed, Chŏngdo, Hyangchun, Yŏngjŏng, Anchŏn, and Haeju, along with their escorts, attacked a force of four Columbian battleships and their supporting cruisers and destroyers outside the burning city of Baumburg. Neither side had fire-control radar, forcing the ships to rely on their spotlights to locate enemy ships at close ranges, a risky maneuver in which the IMN relied on its intensive emphasis on night-combat training. Despite this effort, however, the Chŏngdo only scored half a dozen hits over the course of the engagement, none of them fatal. The heaviest damage to Columbian warships at Frederick's Point came from Menghean heavy torpedoes, which had been fired only to break the enemy formation. Chŏngdo also suffered damage from small-caliber and secondary gunfire, though her most severe damage came in the morning, when a 21-inch torpedo from a Columbian submarine struck underneath her forward funnel. Her entire #2 turbine room flooded, forcing her to dodge aerial attacks under reduced power the next day.
Chŏngdo in the late war
After she limped back to the drydocks at Dongchŏn, a subsequent analysis of the damage revealed that the torpedo had punched through the outer hull and detonated inside the torpedo protection. The geometry of the layered protection area redirected the force from the explosion not outwards toward the surface, but inwards toward the seams connecting the innermost torpedo bulkhead to the armor deck above it. These easily ruptured under the pressure, creating a seven-meter-long horizontal gap through which water and fuel could spill over into the boiler space once all four vertical watertight compartments had filled up. Menghean engineers hypothesized that the same problem had led to the loss of the Sunju, noting that the latter ship initially reported no flooding in the machinery and magazine spaces but that her condition worsened over time well after the torpedoes had hit. Shipyard workers repaired the breach and reinforced the seams along the rest of the torpedo bulkheads, but a complete solution would have required a thorough rebuild of the hull, which was not possible under wartime conditions.
After her repairs were complete, Chŏngdo transferred to the Khalistan theatre, though she spent little time in the open ocean due to the superiority of Allied naval forces after 1941. Menghean fuel supplies were also running low, due to turmoil in Maracaibo and intensifying Allied submarine warfare in the South Menghe Sea. Chŏngdo mainly served as a deterrent, transferring to high-risk areas but seldom leaving port.
See also