In July 1922, after Japan had signed but not ratified the Washington Treaty, a new naval program proposed four new
10,000 ton cruisers, as well as two more 7,500 ton cruisers, which was the Aoba class. Authorized in March 1923
the new 10,000-ton design was known as large model cruisers. The original requirement was for eight 200mm guns
in three twin mounts forward and one twin mount aft, four 120mm (4.7-inch) guns, eight 610mm torpedo tubes in
four twin fixed mountings, protection against 200mm shells in indirect fire and 6-inch shells for flat trajectory direct
fire for critical areas, a 10,000 nautical mile range at 13.5 knots, and a maximum speed of 35.5-knots. Captain Hiraga
Yuzuru was assigned as Constructor for the design. Captain Hiraga convinced the naval staff to some changes to the
requirements. These were an increase in main armament to ten 200mm guns, reduction of range to 8,000nm at
13.5-knots and deletion of torpedo armament. Captain Hiraga thought the torpedo mounts, located inside the hull
above engine spaces, presented as much danger to the new design as to the enemy. Hiraga was promoted to Rear
Admiral and Lieutenant Commander Fujimoto Kikuo took over the design. The design was approved on August 23,
1923. The new cruisers were to be 10,000-tons standard in English tons, 11,850 metric tons at 2/3 trail
displacement, so the original construction order had the ships meeting the terms of the Washington Treaty.

However, additions were quickly made to the design, each of which added weight. The Torpedo Branch convinced
the Naval General Staff to add the four twin tube torpedo armament back into the design and the staff increased the
secondary to six 120mm HA single gun mounts. While the ships were under construction the twin tubes were
changed to triple tubes and in 1928 a deckhouse on either side of the bridge and forward stack was added for
additional living accommodations. The Naval General Staff calculated that these changes would add 500 metric tons
and that the revised 2/3 trial displacement would be 12,350 metric tons. Since the original design was right at the
treaty limit, the staff knowingly exceeded treaty limitations with these additions. Called the Myoko class, the first of
the cruisers to complete was Nachi. The trial displacement of Nachi was 13,338 metric tons, which was 12% over
design trial displacement. This would place the ship at about 11,250 tons standard, clearly in violation of treaty limits.
Of course the Japanese reported the design as in compliance with the treaty.
Nachi was the flagship of Vice Admiral Takeo Takagi, commander of Main Body, Eastern Invasion Support Force.
The 5th Cruiser Squadron was down to just Nachi and Haguro, as Ashigara was acting as flagship for Vice Admiral
Ibo Takahashi, overall Southern Force commander, and the Myoko was at Sasebo for repairs. The eastern invasion
force sailed on February 19 but their southward passage was not confirmed by ABDA command until February 24.
Admiral Doorman’s strike force consisted of the heavy cruisers, HMS Exeter, USS Houston, the Dutch light
cruisers, Java and De Ruyter, along with the HMAS Perth. With minimal reconnaissance the allied force started
making a series of sweeps in an effort to find Japanese troop convoys. Doorman’s cruiser were just returning to
port at 14:00 February 27, when Admiral Helfrich ordered him to immediately sortie against the eastern Japanese
troop convoy. The ships and their crews were tired but Doorman headed back out to sea. It was not long until he
ran into the Japanese forces screening the troop convoy. Further north of the Japanese forces were Nachi and
Haguro, along with four destroyers. At 15:47 Nachi and Haguro opened fire on Houston and Exeter. Nachi scored
the first serious hit at 16:38 when she set Exeter afire. Two minutes later, one of the torpedoes from Haguro’s
spread blew up the Dutch destroyer Kortenaer.Contact was broken and the damaged Exeter detached to head for
safety. At 22:33 when the Nachi, Haguro, Jintsu and eight destroyers regained contact with the allies there were
just the Houston and three light cruisers left in the allied force. In this segment of the battle the Nachi and Haguro
engaged the four allied cruisers by themselves. Long range gunfire again failed to hit on either side but then
Japanese fired more torpedoes, eight from Nachi and four from Haguro. As they would continue to prove through
1942 and 1943 the 24-inch Japanese Long Lance torpedoes were the battle winners for the Japanese Navy. One hit
De Ruyter and she soon sank, taking Admiral Doorman with her. In a few minutes another struck Java and she
quickly sank. The surviving Houston and Perth broke contact and headed back to Batavia on the western end of
Java, while the Exeter, Encounter and US destroyer Pope were at Surabaya on the north center coast of Java.

On the evening of February 28 the Exeter force put to sea again with orders to escape to Ceylon. Waiting for them
were Nachi, Haguro and two destroyers. On March 1 at 09:00 the Nachi and Haguro spotted the Exeter group. For
the next 40 minutes the Nachi and Haguro maneuvered until they had cut off Exeter from returning to Surabaya.
Then the other two cruisers of the class, Ashigara, Myoko and two destroyers appeared in the west. Now all four
members of the Myoko class had the crippled HMS Exeter and two destroyers boxed in a trap. At 09:40 both sides
started firing. The Ashigara and Myoko were to the north of Exeter and the Nachi and Haguro to the south.
Torpedoes from either or both Nachi and Haguro struck Exeter and she sank at 11:30. At 11:35 Encounter went
down due to hits from Ashigara and Myoko. The USS Pope was the last to go, when she too succumbed to
overwhelming fire at around 12:05. The Battle of the Java Sea had lasted two days and was an overwhelming
victory for the Japanese Navy. In June 1942 Nachi was selected as flagship 5th Fleet in the Aleutian landings under
Vice Admiral Hosogawa, as a diversionary operation to the main thrust at Midway. As flagship of 5th Fleet Nachi
remained in the north and did not participate in the Guadalcanal campaign. Nachi and Maya escorted reinforcements
to Attu in the Aleutians from March 7 to 13, 1943 and on the 23rd of the month departed on another escort
mission. On March 27, 1943 the two cruisers made contact with USS Salt Lake City and USS Richmond. In this
engagement, known as the Battle of the Komandorski Islands, the out-gunned USN force acted very aggressively.
Vice Admiral Hosogawa, 5th Fleet commander aboard Nachi, acted more defensively in that he blocked any
approach to the three troop ships that were being escorted. The battle was another long-range gunnery duel in
daylight, lasting almost four hours. Salt Lake City was heavily hit and if the Japanese cruisers had closed with the
two American cruisers, they probably could have sunk her. As it was Hosogawa stayed with his transports. No
ships were sunk for either side, although Maya fired 904 8-inch shells and Nachi 707 shells. They also launched
twenty-four torpedoes, all of which missed at the long range of the engagement. Nachi was hit by five five-inch
shells from Salt Lake City, one of which penetrated the forward face of #1 turret and jammed it. Hosogawa was
replaced as Fleet commander after this battle.
In October 1944 Admiral Shima with Nachi, Ashigara, the light cruiser Abukuma and three destroyers started in
Chinese waters and made towards the southern entrance to the Surigao Strait. Their mission was to support Fuso,
Yamashiro and Mogami under Admiral Nishimura in forcing the Surigao Strait and attacking shipping within Leyte
Gulf from the south. Shima’s force arrived at the strait’s southern entrance 45 minutes after Admiral Nishimura
had passed north on the night of October 24. As Shima steamed up the strait, the remnants of Nishimura’s force
was scrambling back southward. Only Mogami was left of the heavy ships. On fire but still making eight knots,
she was sighted by Nachi, which was Shima’s flagship and leading the column. From Nachi, Mogami was
thought to be dead in water. It was not until Nachi was close aboard Mogami that it was realized that the tough
Mogami was still under way. By then it was too late and Nachi embedded her bow into the already stricken
Mogami. As she broke free, Nachi left part of her bow still wedged in the side of the other cruiser. Nachi was
now reduced to 20 knots speed, Shima retired to the south without making contact with allied ships. Ashigara and
the damaged Nachi made for Manila Bay. After losing her bow at Surigao Strait in her collision with Mogami, she
had safely made it to Manila Bay but on November 5, 1944 was discovered by aircraft from USS Lexington near
Corregidor. In an incredibly savage attack, the hull of Nachi was blown into three parts. Nachi has hit by nine
torpedoes, twenty bombs and rocket fire from the aircraft. The Aoshima Nachi 1943 is available from