Koko Kyouwakoku (Republic of Koko)

Saimei Class Heavy Cruiser:

By 1924 Cruiser production for Koko no Kaigun was in full swing, with no less than sixteen units already in service or under construction. As the Naval Staff considered the number of such sized ships to be largely adequate (The IJN had the same number of modern units in service or under construction too) building priorities switched towards larger units. As it was common and accustomed practice KnK looked at IJN designs, focusing on the Aoba and Myoko classes.
The Aoba was deemed too small, with Myoko feeling a bit too ambitious at the same time. The board thus designed a class of ships that was roughly midway between the two.
The hull measured 194,59m in length overall (192,43m at the waterline). beam 19m and draft 6,5m for a standard displacement of 9.603t standard and 11.527t at full load. Main armament consisted of four 200mm (7.9-inch) twin turrets, two fore and two aft. Secondary armament was four single 120mm (4.7inch) guns, placed on raised platforms. Position of the secondary armament was chosen to allow space on the weather deck for four 610mm torpedo tubes and two armoured reload boxes (which contained four warheads each). This allowed to move the torpedo armament out of the hull compared to both Aoba and Myoko, freeing extra space for crew and machinery. two single 7.7mm machine guns for anti-air defense completed the ship's planned armament. The armor protection called for a 12° inclined belt 102mm thick to protect machinery spaces, plus 153mm for magazines, split between a 102mm extension of the main belt and a second 51mm internal belt. 74mm diagonal bulkheads connected the outer belt to the forwardmost and aftmost barbettes. Torpedo bulkheads were 29mm. Deck thichness was split between a 35mm lower and 16mm upper deck with 38 to 48mm thick plates protecting the boiler uptakes. Turrets were protected by 25mm of armor and barbettes by 76mm plates.
Twelve all-oil-firing boilers were also installed generating 120.000shp and powering four sets of geared turbines driving as many propellers for an expected top speed of 35,5 knots. Endurance was planned at 7.000 nautical miles at 14 knots. Aircraft handling was centered around an hangar and two catapults with the capacity of operating two to three seaplanes. Complement was 690 officers and men.
Approved in 1925 as class of four, the first ship was laid down at Toumachi Naval Arsenal in 1926, launched in late 1927 and finally commissioned in spring of 1928. The cruiser, named Saimei, meet all her expected requirements, reaching just shy of 36 knots with ease during her trial runs in Toumachi bay. Externally, the ship resembled a larger Aoba class with some elements reminiscent of the Myoko class sprinkled in, she was also the first ship in Koko no Kaigun to be fitted with an aircraft catapult, preceding the submarine tender Hakugei by a few months. Between 1928 and 1931, she formed Sentai 3 with the light cruiser Yakogoro while her sister was beign built.
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The second unit of the class, Nanto, was laid down in early 1928 at Toumachi naval Arsenal, a few months her sister had been launched. Construction went on until the hull cleared the slipways by mid 1930. As the London Naval Treaty intervened, Koko no Kaigun had to cancel construction of the third and fourth ship, precluding the plan for cruisers to proceed as planned. Koko would still manage to lie on the class displacement, claiming it was 8.500t standard in order to squeeze some more tonnage to keep other cruisers in service.
At this point the Naval Staff decided to delay Nanto's completion in order to fit more advanced equipment on her. The main gun turrets were switched with the newer Model-E 203mm/50 that equipped the japanese Takao class (the discarded turrets were reused for coastal-defence purposes), starting an anomaly between the two sisters, with Nanto beign able to elevate her guns up to 70° (although only up to 55° was considered pratycal) and Saimei only up to 40°. The 120mm guns recieved shields and two 40mm machine guns replaced the 7.7mm ones. She also had extra protection for her steering gear with 38mm plates on sides, 25mm fore and aft and 19mm on top and the conning tower and steering wheelhouse were armored with 21mm thick plates on sides and 14mm ones on top. More powerful Type2 catapults weres fitted instead of the Type1 of Saimei, the boat and aircraft crane was replaced. The four fixed torpedo tubes were replaced by two twin rotating launchers for better arcs of fire. The forward supersructure was heavily modified: a more advanced fire-control equipped was fitted, and the navigation bridge was relocated one deck higher. RDF equipment moved to the former bridge area, and two enclosed lookout posts were fitted on each side. The 1,5m navigation rangefinders got relocated, and were of a newer model. Such fitted Nanto was commissioned in December 1931, she displaced slighly more than Nanto, at 9.867t standard.
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After years of service Saimei entered the yards in late 1937 for for a main reconstruction that lasted until early 1939. New fire control equipment was fitted, with a main director set with a 6,5m rangefinder mounted atop the main superstructure and a single backup director aft of the mainmast. Another set with a director and a 4,5m rangefinder was fitted on each side of the birdge structure to control anti-aircraft guns. the 7.7mm machine guns were landed, replaced by two twin and four single 25mm machine guns at midship and a quadruple 13mm one in front of the bridge, machine gun directors were fitted abreast the after funnel. A new searchlight platorm was added aft of the bridge, new deckhouses were added around the aircraft and boat deck and the airwing saw the old vastly outdated Nakajima E2N replaced by two E8N. Saimei's bridge was relocated and enclosed one deck higher, like on Nanto. Her 200mm/50 main gun barrels replaced with the newer 203mm/50 ones, turrets were refurbished and recieved a new powder and shell handling system but not replaced. The Naval Staff planned to rectify this problem by exploiting the already reopened production lines for heavy Cruisers by building some more extra turrets to replace Saimei older ones on a later date. Armor-wise, some areas were given extra protection, she got the same steering gear and wellhouse protection Nanto had since commissioning. Bulges were fitted to provide extra boyancy given the increased weight, improve underwater protection and get extra bunkerage. Beam thus increased to 20m and displacement to 10.522t standard and 12.185t full load. Engines were refurbished but not increased in power. Top speed dropped slightly to 35knots while endurance increased to 8.500 nautical miles at 14 knots. Complement increased to 735 officers and men
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Nanto was recalled for her refit between 1937 and 1941, mostly following the same lines of Saimei but sporting differencies as well. Since the navigation bridge was higher on her superstructure already, Nanto had hers simply enlarged and upgraded. The new searchlight platform was placed between the aft funnel and mainmast instead, as the machine gun directors were located abreast the forefunnel. Nanto had also a larger three-legged forward mast compared to Saimei smaller pole-mast and sported three triple 25mm machine gun mounts. The aircraft complement was one Mitsubishi F1M and one Aichi E13A. Last and most important change, Nanto had larger torpedo bulges with an additional 29mm bulkead for increased torpedo protection. This resulted in a 20,6m beam and a displacement of 10.789t standard and 12.589t at full load. Nanto boilers and turbines recieved further refubishment compared to those of Saimei, so that they could generate an higher output of 126.000shp, enough to match or even exceed -she made 35,5 knots on trials- her sister top speed despite the increased displacement. Thanks to the increased bunkerage allowed by the larger bulges, Nanto range was the same 8.500nm of Saimei.
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At the start of the war the two sisters took part in the operation to capture Midway before being called south to Wake Island as the first Japanese attempted landing had failed on december 11. Between the 16th and 21st of the same month Saimei and Nanto provived nightime bombardment on the US held island, falling back during the day to avoid US air cover, until the second japanese invasion force came to succesfully occupy it on the 23rd. After a few weeks of drills and training at home, both ships were detached to Rabaul in late February 1942. They later accompained japanese forces during the attempted invasion of Port Moresby and the Battle of Coral Sea.
With US forces landing on Guadalacanal on August 7th, Saimei and Nanto were attached to Mikawa's force and Steamed down the slot in reponse, engaging a combined US, Australian and Recherchean fleet in what would be known as the Battle of Savo Island early on August 9th.
After slipping undetected between the US picket line Mikawa's formation sighted the lone USS Jarvis, which had been damaged in an air attack earlier and was leaving for repairs in Australia. Both Furutaka and Saimei launched torpedoes, Furutaka missed, but two of Saimei long lances hit the wounded destroyer, sinking it with all hands. Still incredibly undetected, the Kokoan-Japanese formation took by suprirse and engaged the southern and northern Allied flotillas, sinking four cruisers (Canberra, Astoria, Quincy and Vincennes) and damaging two more ships in a one-sided hail of shells and torpedoes. During the engagement Saimei and Nanto strayed east enough that they drove the attenion fom the Allied eastern flotilla. Despite initially ounumbered, they still managed to inflict heavy damage before the rest of Mikawa regrouped with them. Together they thus also sank HMAS Hobart and two destroyers, almost crippling Australia and damaging the USS San juan, HMRS Norseman and Anvil.
As Mikawa ultimately decided to fall back without engaging the troop transports, fearing the arrival of US carrier-based aircrafts in the morning, the Kokoan-Japanese fleet steamed north and then west leaving behind a crippled enemy formation, all of that achieved with little to moderate damage suffered in return. The Sinking of Kako by the US submarine S-44 not considered significant enough to dampen the enthusiasm. Saimei and Nanto themselves had suffered a few hits but all damage had been repaired by the time they sailed again with the Japanese carrier fleet at the battle of Eeastern Solomon between august 23 and 25th 1942.
Their next surface engagement would be on October 11th at Cape Esperance. While on a bombardment mission of Henderson filed together with he IJN cruisers Aoba, Kinugasa and Furutaka they were intercepted by a US and Recherchean formation. As admiral Goto, commanding the IJN/KnK force from Aoba, mistook the enemy ships as friendly reaction was slow at first. While Aoba and Furutaka got the brunt of enemy fire, Saimei and Nanto turned to port following Kinugasa, only to be hit by the USS Boise, Helena and HMRS Quagi in return. A chaotic gunfight ensued: Boise, already damaged by Kinugasa was finished off by Nanto, which then hit Helena multiple times. Saimei damaged Quagi but suffered dozens of hits in return before she could brake off and retreat. The engagement resulted in ships sunk (Fubuki, Furutaka, Boise, Duncan) and heavily damaged on both sides and was mostly inconclusive.
Nanto suffered five main caliber hits from Helena, one boiler out and a serious gasoline fire that gutted her aircraft-handling deck. She was repaired at truk and was back on station by early December 1942. Saimei fared much worse instead, she had all but one of her main turrets knocked out of action, damaged boilers, mangled forward mast, badly holed superstructure and suffered numerous fires and casualties. She -together with Aoba- recieved emergency repairs at Shortland, then limped to Truk for some temporary repairs before being sent back to Toumachi for more extensive ones. She finally recieved the Model-E turrets that was supposed to be fitted with since 1939. The forward searchlight platform was lowered and relocated further aft and the original foremast replaced with a three-legged one. Type13, Type21 air-search and Type22 surface-search radars were fitted on both forward and main mast. An anti-air command platform was added above the navigation bridge, with a smaller auxiliary one over the battle bridge. Light anti-air armament was improved with the removal of the quad 13mm piece and addition of five triple 25mm mounts. Lower deck portholes were sealed and the airwing was changed to one F1M and one E13A. Saimei finaly retured to service after seven months of work in early June 1943.
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While her sister was under repairs Nanto sailed en-masse with the bulk of the Kokoan and Japanese fleet in the inconclusive carrier battle of Torres islands. With Saimei repaired and redeployed to Rabaul the two cruisers sailed together again to escort carriers at the battles of Solomon Sea (June 26th 1943) and Stewarts Island (February 2nd 1944) but saw little service otherwise as growing enemy air-power in the region made risky to take the seas alone or in surface-only groups during the day. They did provide a few night-time shore bombardment against US forces after their September 1943 amphibious landings in New Georgia.
Nanto returned to Kokoan waters in June 1944 for her wartime refit. She had many portholes sealed, recieved anti-air command platforms, Type13, Type21 air-search, Type22 surface-search radars and a Thiaria-derived TypeR4CA fire-control radars for her anti-air directors. Modifications were done to the superstructure with the removal of redundant rangefinders, opening shielded lookout posts and moving the signaling searchlights to new platforms. A new deckhouse serving as ready-service ammunition lockers and ready rooms for anti-air guns was added aft of the n°2 turret. Machine gun tally was increased to thirty-three barrels by adding eight triple 25mm mounts.
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Back in the Solomons in August, Nanto and Saimei spent the next three months shelling islands at night in the futile attempt to slow US amphibious operations and avoiding aircraft and submarines attacks during the day. The two would be ultimately damaged on November 5th 1944 during the US carrier attack on Rabaul. Although damage was light Koko no Kaigun naval staff decided to move the two ships to Truk for repairs in light of the general worsening wartime situation and recent high-profile losses the Navy was suffering. The two cruisers stay at Truk didn't last long, as intelligence hinted a significant enemy attack was coming. Saimiei and Nanto evacuated the lagoon on February 10th 1945, one week before a devastating carrier raid made the base inoperable.
Saimei returned to the yards in april 1945 for a new refit. More portholes were closed, an hydrophone and IFF set fitted. The radar suite was improved with the installation of TypeR2FA and Type24 air-search sets, plus TypeR5CD and TypeR12CAD fire-control radars for the main and dual purpose guns. Light anti-air armament was increased to twent triple and twenty-two single 25mm machine guns for a total of eighty-two barrels. The F1M floatplane was disembarked and another E13A carried in its place. In early June she was repainted blue, a darker tone on her hull and a lighter one on decks and superstructure, plus a black n°3 turret.
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In late June the two sisters escorted and provided anti-air duties for the Combined Kokoan/Japanese carrier fleet at the battle of the Philippine Sea, a tactical success and strategic defeat at the same time.
Nanto was refitted again in September 1945, mostly recieving the same upgrades of Saimei but with some exceptions and improvements. She got a Type33-kai surface search radar that could also act as a backup fire control set and nine twin 40mm machine guns in addition to the eleven 25mm triples and twenty-two single ones. Her camouflage scheme was slightly more elaborate, with very large patches of light blue, dark blue and black on the hull and superstructure.
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Moved to Brunei for readiness in light of a feared enemy operation again the Philippines Saimei and Nanto were assigned to Shima and Nishimura southern force after US troops executed a landing at Leyte on October 20th 1945. Part of an Attemped a pincher movement on the beacheads the southern force entered Surigao Strait on October 24th shortly before midnight. Awaiting for the five batleship, eleven cruiser and a dozen destroyer strong Kokoan/Japanese fleet was an American, British and Recherchean formation that totaled six battleships, thirteen cruisers and twenty-eight destroyers. Thanks to superior fire-control equipment and positioning the US/RN/RRN formation got the upper hand in what at first developed into a chaotic and fierce battle reminiscent of the "barroom brawls" of Guadalcanal, with heavy losses and damage done to both sides.
Both Saimei and Nanto launched torpedoes but failed to score any hits, then engaged in a fierce gunfight with the US cruisers Louisville, Portland and Minneapolis. While manouvering into a better firing position Saimei was hit by a torpedo fired by the USS Monssen that damaged one of her turbines and started a fire near the aircraft deck. Made visible to the enemy by her own flames Saimei was soon hit by an hail of shells from the three US cruisers and the Battleship Mississippi that laid waste of her upper works and silenced all her guns in minutes. The port torpedo tubes exploded shortly after, further worsening the fires and dooming the ship. As crew started to escape the raging inferno the IJN Michishio attempted pulling survivors from the water, only to be hit and later finished off by the USS McDermut and Hutchins. Saimei eventually rolled over and sank, 302 survivors were pulled from the waters the next morning by US ships and made prisoners until the end of the war.
Nanto was also hit during the same action recieving no less than twenty-three hits that damaged the radar and chart rooms, one of the main gun turrets and two of the 120mm pieces. One of the aircraft catapults was destroyed and both E13As written off, multiple machine gun mount were also inoperable. Shell, Splinters and shrapnels also inflicted various amounts of damage to the machinery spaces, forcing the speed to be reduced lest the ship risked to end up dead in the water. The crew managed to jettison all torpedoes still on board and control the fires, allowing the damaged ship to limp away from the battle.
Nanto sought refuge in Manila bay for repairs, where works to repair some of the engine damage started almost immediately. US carrier acircrafts attacked Japanese and Kokoan units a few days later, on October 29th. Nanto managed to get underway and, despite two near misses, succesfully left port and escaped. Engine troubles resurfaced shortly after, so the ship reached Formosa and docked at Kirun (now Keelung) for further works. Makeshift repairs were halfway done when, early on November 7th, words arrived about the start of Koko uprisings. Uncertain about what the reaction of local Japanese armed forces cold have been, and unwilling to risk internment or even being shelled, Nanto's crew decided to departed as hastily as possible. The cruiser got underway and left Kirun at dawn. Alone in waters infested by either US or Japanese units Nanto made up to 25 knots, pushing her damaged engines in a race to get home as soon as possible. The battered cruiser finally made to Hoshiguma on the 12th with a jammed gearbox and two blown boilers. Her crew joined the rebels under Karasawa. The ship was surveyed and the engine damage was deemed to be irreparable, so Nanto was declared a total loss in December 1945. She sat a hancor in Hoshiguma as a floating anti-air battery past the armistice and to the end of WWII in September 1946. Immediately taken out of service she was eventually scrapped starting in early 1947.

Ships in class: (laid down-launched-commissioned - fate)

Saimei 1926-1927-1928 – Sunk 1945
Nanto 1928-1930-1931 – Decommissioned 1946
unnamed 1930-/-/ - Canceled in 1931
unnamed /-/-/ - Canceled before being laid down in 1931

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