Tone class cruisers (1937)

Tone class cruisers (1937)

Japanese Navy Heavy Cruisers Tone, Chikuma.

The last IJN heavy cruisers

The Tone class cruisers, IJN Tone and Chikuma, were part of the 1932 supplemental plan, including light cruisers still limited under the Washington Treaty, but in 1938-39, Japan tore off all treaties and reconsidered her own naval plan. It was decided for example to complete them as heavy cruisers but with their initial 155 mm (6-in) triple turrets discarded for 8-in twin turrets, while their hull was strengthened considerably, reaching a displacement way over all treaty limits.

Their hybrid nature was however unique, with all their artillery concentrated forward mostly to compose a thicker, but more compact immune zone and improved living quarters as well as leaving their aft deck free for extra aircraft accommodations extensive reconnaissance with six instead of one to four floatplanes. So they were not “hybrid” either despite the appearance. Both cruisers were very active in WW2, between Wake, the East Indies, the raid on Australia or the Indian Ocean, Midway, Guadalcanal, Rabaul, the Philippines sea and Leyte. IJN Tone survived the war and was destroyed at Kure but Chikuma was lost in the Battle off Samar on 25 October 1944.

IJN Tone

From Light to Heavy Cruisers by treaty

The 4th fleet incident and consequences

The development of the Tone class was very much chaotic. They started as planned FY 1932 as treaty-bound light cruisers, very much similar to the Mogami class, a repeat with a few improvements, always on the apparent 10,000 tonnes standard limits.

In 1936, rising nationalism and militarism in Japan led to rip of treaties altogether. From then on, Japan would disregard all limitation imposed by the 1921 treaty of Washington, the 1930 treaty of London and 1935 second London Conference. Natually the first sensible measure was to come back to a 8-in (203 mm) armed heavy cruiser. The switch from “light” to “heavy” was made simply by swapping to 8-in guns, by treaty virtues. In any case, after the many design modifications implied, this led to a much havier design.

The motivation behind this redesign, which delayed the launching of both vessels by years, was double. Initially, the Tone-class cruisers were simple repeats, ordered as the 5th and 6th Mogami class cruisers, with detailed improvements the trace of which is no longer there.

Construction began based on these prospects in Mitsubishi Naval Yard, espectively on 1 December 1934 and 1st Otober 1935. However in between the IJN Mogami was just making her sea trials, revealing serious weaknesses in the hull design. It was compelled by the “Fourth Fleet incident” on 26 September 1935. For memory, the 4th fleet under command of Hajime Matsushita was playing the “opposing force” in large scale exercizes when very foul weather started to disturb operations, soon to degenerate into a one of the fiercest typhoon Japan ever experienced. Two ‘Special Type’ destroyers, Hatsuyuki and the Yūgiri had their bow ripped off by waves while all heavy cruisers taking part received grave structural damage. The admiralty concluded it needed to quickly reinforce all ships, even if it’s meant retiring them for lenghty reconstructions. This was the fate of the Mogami class and many others. It was also decided to change future (and just started) designs construction.

1936 retirement of the second London Conference

The second was Japan’s refusal to comply to the limitations of the last Naval Treaty. Let us remember that in 1933, after the 1929 krach and unsuing grave financial crisis that wrecked the economy of the whle world, including Japan, amidst acute social discontent, saw the widespread rise of extremism. The rise of Hitler to power was mirrored in Japan by a more proactive military clique in Japan, starting with a coup d’état attempt in Japan by March 1931, launched by the radical Sakurakai secret society within the Imperial Japanese Army, aided by civilian ultranationalist groups. By March 1935, Hitler himself announced that Germany would no longer abide by Part V of the Treaty of Versailles regulating the size and composition of German armed Forces, while Mussolini’s Italy started a colonial campaign in Abyssinia, a sovereign nation, leaving the league of nations powerless to prevent it.

Japan’s policies from there was largely decided by militarists and decisions towards the navy were influenced by the Vinson-Trammell Act voted in 1934, or the National Industrial Recovery Act of 1933. So by 1934 Japan announced they planned to leave treaties in two years and although at the Second London conference of 1935, delegates showed willingness to negotiate, they eventually left the conference by January 1936 while considering that older treaties expiring on December 31, 1936 they were in their right to follow their own path without violating the law.

That’s why notably Japan refused to allow British inspectors to know about a remuored colossal new secrelty built battleship. On the same vein they were now able to rebuilt all their cruisers well above old tonnage treaty limits, which they did, plus new ones well above the 12,000 tonnes mark standard as well as “super cruisers”. note.


The first point dictated a serie of design revisions, notably reinforcing the hull with extra barcing, thicker plating in sensible places, and since cracks in the hulls of the new Mogami indicated grave shortcomings in electric welding for the seams, it was decided to go for more traditional and proven techniques. For the second point, from the Mogami to the Tone in their definitive form, was not only to swap to 8-in turrets, basically engineers could take the model used on the previous Nachi and Takao classes, but the admiralty wanted a better protection of it’s vitals, around the turret, and came with the old idea of concentrating artilery like on the 1927 Nelson class and just launched Dunkerque class.

It was decided for the new cruisers to reduce the main armament from five triple turrets initially planned (as ONI believed) to four concentrated forward and just a single raised turret in no.2 position (or “B” turret), thus reducing top weight over the deck and and devoting to on-board aviation on the freed aft space as the admiralty was ready to sacrifice firepower to test the concept of “reconnaissance cruiser”.

This was the only time Japan ever came with such design for a cruiser, and imposed radical changes in the hull and superstructure. The two hulls stayed virtually untouched for several months, before a first emergency design was presented to strenghten the hull, and then proceeded slowly as a definitive design was worked out, literally from the keel to the weather deck. The whole process mostly concerned the artillery arrangement, as all the rest was just still directly from the Mogami design: Superstructure, powerplant, secondary armament, torpedoes, and AA armament and most of the parts and details. Nevertheless, it took three full years until launch.

Hull and general caracteristics

Basically, the Tone looked like a Mogami on which the main armament was rearranged forward, pushing back the superstructure of the Mogami, but keeping the same basic hull form, just shortened and strenghtened. The hull measured 189.1 meters long (620 ft 5 in) – versus 201.6 m (661 ft 5 in) and the beam 19.4 m (63 ft 8 in) versus 20.2-20.6 m (67 ft 7 in) on the rebuilt Mogami and Susuzya sub-classes. The narrower waist was a decision to maintain a favorable hull ratio and preserve speed. For Draught however it was 6.2 m (20 ft 4 in) on the Tone versus 5.5 m (18 ft 1 in) on the Mogamis.

This resulted in deeper vessels with a tonnage jumpring to 11,213 tons (11,392 tonnes) standard and 15,200 tons (15,443 tonnes) fully loaded, versus originally 8,500 tons standard load and 10,980 tons at full load for the Mogamis before reconstruction. The gap of 1,500 tonnes towards the maximal allowed tonne was a reserve for upgrades. But by doing a 200 meters vessel based on such displacement, troubles were ahead. The Tone was shorter, narrower, and yet far heavier, most of the extra tonnage going into structural reinforcement and thicker construction plating, plus riveting instead of welding in many places, also making the whole hull heavier. Though, the construction of Tone being more advanced, she had far more wielding seams than Chikuma, so making her a bit lighter.

Despite the concentration forward of the armament, the main superstructure was not pushed back that far, being ahead of the mid-section, with the truncated funnels and well spaced main mast aft, creating a rather aesthetical result. Seen from afar, it was difficult in fact to distinguish them from other heavy cruisers. Indeed, compared to the Nachi/Takao her forward deck was just longer by the lenght of a turret.


2-views of the class

Tone had some wielding before changing track, but Chikuma was an all-riveted design, like the Nachi/Takao. The undulating hull was dispensed with, superstructure was less extensive to spare weight, preserve stability. The main belt armor was 150 mm (5.9 in) thick along the machinery spaces, and even 225 mm (8.9 in) next to the magazines; It was extending down underwater to 9 feet (2.7 m) and tapered down much to meet the anti-torpedo bulkhead, and itself ended down to the inner double bottom, covering most of the lenght. Here are the details:

  • Main belt, citadel: 145 mm (5.7 in)
  • Belt, machinery space: 150mm (5.9 in)
  • Belt, ammo spaces: 225 mm (8.9 in)
  • Armoured deck: 30 mm flat section, 65 mm slopes and above ammo/machinery/steering spaces (2.6–1.2 in)
  • Main turrets: 25 mm (2 in)
  • Main turret barbettes: 25 mm (2 in)


The main engines of the Tone class were similar to that of Suzuya and Kumano, to gain time, so the Suzuya sub-class, based on the original design calling for a repeat of the Mogami class. They had four propellers, driven by two Gihon geared turbines, themselves fed by eight Kampon double-ended, oil-fired boilers, for a total output of 152,000 shp (113,000 kW), providing a top speed of 35 knots (65 km/h; 40 mph). It’s two knots less than the 37 knots (69 km/h; 43 mph) of the initial Mogami class (less after reconstruction).

These cruisers had a range of 8,000 nautical miles (15,000 km; 9,200 mi) at 18 knots (33 km/h; 21 mph), the same as the Mogami, but at 14 knots (26 km/h; 16 mph). Technically they carried more oil to achieve the same range faster. The very last planned cruisers, the Ibuki class, had the same powerplant, but also for 35 knots and a lesser range, 6,300 nmi (11,700 km; 7,200 mi) at 18 knots. These were a minor improvement over the last pair of the Mogami class.


ONI plate showing the 1939 supposed appareance of the Tone class. See the old style bridge and triple turrets.

After the 1936 modifications, they ended with 8-in turrets all forward, a powerful torpedo armament plus their extended scout capacity, inspiring the reconstruction of the Mogami in 1942. Their anti-aircraft artillery started initially with twelve 25 mm AA guns in six twin mounts, up to thirty in early 1942 and by 1945 fifty-seven, not preventing Tone to be sunk by aviation.



As regarding the main artillery of the Tone class, substitution to twin 203 mm (Model 2) turrets from triple 155 mm turrets took place during construction. The twin turrets were said to be of the E3 type, with identical characteristics to those of the Mogami “modified E2” installed during reconstruction on the Mogami class, except a compensation for the barbettes diameter difference, 5.70 m for the 6-in triple but only 5 m ( feet) for that of the 8-in models.

These were of the 20 cm/50 3rd Year Type naval gun type, design started in 1926 ad in service for the 2-Go in 1932. These built-up guns had an inner A tube encased by a second tube in a full length jacket. Breech loaded with two cloth bags of smokeless powder and Welin breech block, on a Type E gun mount. They fired at 30° to 25 km (15 miles) with a muzzle velocity of 1247 ft/s (380 m/s) for AP shell. On paper the Type E allowed a maximum elevation of 70° but 55° was more practical on the Tone class.


These were the ubiquitous dual purpose 12.7 cm/40 (5 inches) Type 89 naval gun found on all IJN vessels of the time. They were located on four sponsons on the broadside.

AA armament

There too, the AA armament comprised twelve Type 96 25 mm (0.98 in) AA guns in six dual mounts. Over time (see modifications) triple ones, and single ones in 1944 were aded to reach a total of 64 on Chikuma by 1945, and in between were made addition of Japanese Navy Type 93 13.2 mm heavy machine guns in several twin or single mounts.

Torpedo armament

The Tone class, like the Mogami and previous classes, carried an impressive torpedo armament, made of no less than twelve 610 mm (24 in) torpedo tubes (with reloads) in four triple banks placed in niches along the superstructure aft. They fired the legendary Type 93 “long lance” but the Tone class unlike many other cruisers never had the occasion of using them in battle in a decisive way.

Onboard Aviation

Aichi E13A1 model 11, IJN Chikuma, 1941

These Tone class cruisers were the first to carry so many floatplanes. The air group changed over time. At first, it seemed they carried six Nakajima E8N biplanes (as seen on some pictures) or a mix of three E7K1, and three E8N1 “Dave”, all obsolete in 1942. however during the attack of Pearl Harbour they both flew a mix of E13A and Nakajima E4N2 Type 90-2, to have long and short range reconnaissance. They were replaced by five Aichi E13A monoplane floatplanes. Five and not six as they were seemingly larger. The accomodations comprised two catapults installed on either side of the quarterdeck aft, on sponsons, and handling of the planes was done by a lattice crane anchored on a crane pole at the base of the mainmast.

Seaplanes were strapped in chariots rolling on rails with hubs criss-crossing this aft deck and a ramp going to the lower deck long track, able to store two more. There was no hangar through. These models needed to be protected by the elements and were maintained at sea, with the problem of highly corrosive saltwater and extremes of temperatures.

Traditionally in IJN doctrine, seaplane tenders/carriers were used for amphibious operation’s air support, but the cruisers traditionally provided the “eyes of the fleet”, sending their floatplanes in all probable directions of the enemy. By default of a radar, inexistant in 1936 when these cruisers were redesigned, the capacity of bringing six reconnaissance planes allowed to cover far more ocean area.

Construction and modifications

IJN Tone in 1941 and 1945, showing the differences.

IJN Tone was ordered FY 1932, but delayed and eventually laid down on 1 December 1934 at Mitsubishi NyD, launched on 21 November 1937 after redesign, and Commissioned on 20 November 1938.
IJN Chikuma, like Tone, was ordered on 1932 Fiscal Year, but delayed and only started at Mitsubishi NyD, laid down on 1 October 1935, and then completely redesigned, launched otherefore much later on 19 March 1938 and Commissioned on 20 May 1939.

On March 1943, both cruisers received two twin 25mm/60 Type 96 and Type 1 2-go radar. In January 1944 they received also both two extra twin 25mm/60 and four twin plus four single 13.2/76mm AA HMGs. By July 1944 IJN Tone received four extra single 13.2mm/76 and four triple 25mm/60 plus twenty-five single plus two Type 2, 2-go radar and a type 3 1-go radar.

In July 1944 also her sister Chikuma received four extra single HMGs and four triple 25mm/60 plus tenwty three single and rhe same radar suite. The survivor in February 1945 IJN Tone received seven single 25mm/60, and the 21-go radar, and later four extra triple 25mm/60 96-shiki and a third Type 2 2-go radar.

Tone in 1938

Chikuma in 1941

IJN Tone
Author’s illustration – IJN Tone

⚙ Specs 1941

Dimensions 201,5 m x 18,50 m x 5,9 m draft
Displacement 12,400 t. standard; 15,200 t. Fully loaded
Propulsion 4 shaft Kampon turbines 12 admiralty boilers, 152 000 hp.
Speed 35 knots
Range 7,750 nmi (14,350 km; 8,920 mi) at 18 knots (33 kph, 21 mph)
Armor From 130mm (magazines) down to 25 mm decks
Armament 8 x 203 mm (4×2), 8 x 127mm (4×2), 30 x 25 mm AA, 12 x 610 mm TTs (4×3), 6 floatplanes
Crew 850

Sources/ Read more


Conway’s all the worlds fighting ships 1922-1947
Anthony P. Tully, ‘Solving some Mysteries of Leyte Gulf: Fate of the Chikuma and Chokai ‘, Warship International No. 3, 2000
Wildenberg, Thomas. “Midway: Sheer Luck or Better Doctrine”. Naval War College Review 58, no. 1 (Winter 2005).
Brown, David (1990). Warship Losses of World War Two. Naval Institute Press (NIP).
Dull, Paul S. (1978). A Battle History of the Imperial Japanese Navy, 1941–1945. NIP.
Jensen, Richard M. (2001). “Re: Fate of Chikuma and Chokai”. Warship International. International Naval Research Organization.
Jentsura, Hansgeorg (1976). Warships of the Imperial Japanese Navy, 1869–1945. NIP.
Lacroix, Eric; Linton Wells (1997). Japanese Cruisers of the Pacific War. NIP.
Whitley, M.J. (1995). Cruisers of World War Two: An International Encyclopedia. NIP.

Links – Tone description
Navypedia Chikuma: tabular record of movements Tone: tabular record of movements

The model’s corner

Tamiya’s 1/350 Ship Series No.24 Tone

Needless to say, the class has been generously served by all Japanese manufacturers at many scales, from 1:200 by GPM to tabletop games scale at 1:2000/3000, and through the 1:350 and 1:700.
The Tone on scalemates (all kits)
The Chikuma on scalemates (all kits)
3D renditions on Behance

The Tone and Chikuma in action

Tone was at the Battle of Midway in June 1942, then she participated with her sister shoip (same dvision) in the Battle of Solomon Islands in August 1942, Santa Cruz Islands, at the second battle of Guadalcanal in November 1942.

Tone and Chikuma were engaged in the battle of Leyte in October 1944, under command of Admiral Kurita. IJN Chikuma suffered attacks from US Navy aircraft, and sank on 25 October 1944. Tone survived the epic battle, and was based in the home Islands, notably Kure, mostly inactve due to the lack of fuel oil. She was bombed by USN aviation in Kure, during the great raids of the 3rd Air Force in July 1945, and sun in shallow waters on the 25th. She was later captured, loaded with explosives, blasted on situ, her remains still there until 1948. She was scrapped afterwards.

IJN Tone

IJN Tone in 1941

IJN Tone entered service on 20 November 1938, but from the 1st with Captain (later Vice Admiral) Hara Teizo as CEO. She was attached to Yokosuka Naval District, buy by 20 October 1939 Captain Hara is appointed also CO of CHIKUMA as additional duty. On 15 November 1939 Captain Onishi Shinzo took command while the ship multiplied gunnery drills and exercizes. She in December joins the Maizuru Naval District with her sister ship now opertational abidend ready for missions, and by 15 October 1940 Captain Nishida Masao taked command. Exercizes went on in home water (no deployment in China). By 10 September 1941Captain Okada Tametsugu takes command while Nishida is reassigned to IJN HIEI.

Pearl Harbour & Wake

On 26 November 1941 at last, after three years of training, both cruisers are mobilized for Operation “Z”: As part of CruDiv 8, TONE and CHIKUMA departs Hitokappu Bay and Etorofu Island in Kuriles with Vice Admiral Mikawa Gunichi’s Support Force’s BatDiv 3. and the First Air Fleet Striking Force (Kido Butai). So both Tone and Chikuma would take part in the attack on Pearl Harbor. On 7 December 1941, they both launched one Aichi E13A1 “Jake” floatplane for a final weather reconnaissance over Oahu. At 06:30, they launched launched several Nakajima E4N2 Type 90-2 as pickets and patrollers south of the Striking Force. Tone’s own floatplanes flew to Lahaina, but found no target present. On 16 December, CruDiv 8 was ordered to participate in the second attack on Wake Island (the first was repulsed). Tone launched two Nakajima E8N for ASW patrols before and during the operation to watch for a possible reinforcement fleet. After the fall of Wake, CruDiv 8 returned to Kure for upkeep and a refit;

New Guinea and Australia

From 14 January 1942, CruDiv 8 was sent to Truk in the Carolines, to cover the landings of Japanese troops at Rabaul in New Britain. Later, the same took part in the shelling and AA cover for two more operations on Lae and Salamaua in New Guinea. Ten days later, Tone’s floatplanes attacked the Admiralty Islands, and on 23 January 1942, two E13A1 floatplanes and one E8N2 from TONE attack and bombed Buka Island. On 1st February, following the attack on Kwajalein, Marshalls, by Vice Admiral William Halsey from USS Enterprise, Tone departed Truk with the Kido Butai in pursuit, but found nothing.

Chikuma and Tone also took part in the Raid on Darwin, Australia (19 February). Their own floatplane loaded with bombs took part in the attack, while others covered the area for possible reinforcements or targets. Tone’s floatplane reported weather conditions before the raid the attack but its radio failed and it went back without reporting. Another replaced it and met, then shot down an RAAF PBY Catalina, the first “kill” of Tone’s air group. TONE’s floatplane No.2 also located two ships off Cape Foureroy, later sunk by D3A1 dive-bombers from IJN AKAGI. From 21 February 1942 CruDiv 8 escorted CarDiv 1 and DesRon 1 to Staring Bay for refueling and later joined Vice Admiral Kondo Nobutake’s BatDiv 3’s and CruDiv 4’s from Palau to refuel, to create a new battle group to attack the Dutch East Indies.

Battle of the Java Sea

On 25 February was launched Operation “J”, the Invasion of the Netherlands East Indies with a battlefleet under orders by Vice Admiral Kondo (flagship IJN Kongo), and BatDiv 3/2 (KONGO-HARUNA) were detached along CruDiv 4 (ATAGO-TAKAO) joined later by DesDiv 15 from Timor, chasing off ABDA damaged vessels while the remaining forces force supported the carrier attacks on Java with CruDiv 8, DesRon 1 and six tankers.
On the 27th, USS LANGLEY (AV-3) and her escorts, USS WHIPPLE (DD-217) and USS EDSALL (DD-219) are located by floatplanes and soon attacked by 16 GM41 “Betty” bombers from Takao NAG Denpasar, Bali escorted by six A6M2 fighters from Tainan NAG.

They badly damaged LANGLEY, which is abandoned. EDSALL picked up 177 survivors, WHIPPLE 308 and they met the next day USS USS PECOS (AO-6) off Christmas Island to transfer their rescued crews when more bombers arrived, forcing their departure. It’s en route on 1 March 1942 that Tone spotted USS Edsall some 250 miles (400 km) SSE of Christmas Island. It was reported by the E13A by a MARBLEHEAD-class light cruiser and Kondo ordered BatDiv 3/2 and CruDiv 8 to intercept her. She was spotted at 16:02 16 miles away, heading north and CHIKUMA opens fire first, followed by the capital ships but they failed to sunk her. She was finished off by 26 D3A1 “Val” from KAGA and SORYU and HIRYU.

On 2 March 1942 CruDiv 8 and BatDiv 3/2 rejoined the Carrier Striking Force on the 4th, Tone’s floatplanes and those of Chikuma took off to bomb Tjilatjap. On 6 March, IJN Tone rescued a British seaman adrift since his ship was sunk off Java on 27 February, duly interrogated. On the 11th after the surrender of the Dutch East Indies, they arrived at Staring Bay, Kendari, Celebes.

Indian Ocean Raid

Operation C is prepared from staring bay gathering point on 26 March 1942. They soon departed for the Indian Ocean and separated. CruDiv 4’s CHOKAI and CruDiv 7’s SUZUYA, KUMANO, MIKUMA and MOGAMI, the light cruiser YURA and destroyers attacks merchant traffic in the Bay of bengal on 1st April. On the 5th, Tone is covering the Kido Butai, launching 315 aircraft against Colombo, Ceylon. HMS Tenedos, the armed merchant cruiser HMS Hector and 27 aircraft are destroyed. Later Tone’s floatplanes took part in a wide search in which HMS Cornwall and Dorsetshire are spotted and then also attacked and sunk. Tone returned to Japan by mid-April 1942, but immediately assigned to Admiral Halsey’s TF 16.2 desperate chase (notably USS Hornet after the Doolittle Raid).

Battle of Midway

Tone for Opereration Mi was still part of CruDiv 8, protecting Nagumo’s Carrier Striking Force. On 4 June, Tone and Chikuma launched each two “Jakes” to search within a 300 miles (480 km) area, for American carriers. Tone’s floatplane spotted them but the message had to go through the command structure and is not immediately delivered to Nagumo. This crucial delay is what doomed his fleet as his air grpoup was prepared meanwhile with bombs for a second trike and is now entirely ordered to convert to torpedo to launch an air strike instead on the carriers. This takes place while the US air attack began. Tone meawnhile as part of the cover fleet, is also attacked by US carrier aircraft but sustained no damage, although loosing a “Dave”, likeley shot down.


Tone during the battle of the Eastern Solomons, 24 August 1942

With her sister after resupplying back home, she is detached to support Vice Admiral Boshiro Hosogaya’s Aleutian invasion force. But anticipated American counter-attack never materialized, leaving CruDiv 8 patrolling the area for nothing before going back to Japan and being prepared for next operations. It’s Rear Admiral Chuichi Hara which command of CruDiv 8 from 14 July 1942. Bith are sent to take part in the invasion of Guadalcanal

They are ordered south on 16 August with the reconstructed Kido Butai ( Shōkaku, Zuikaku, Zuihō, Jun’yō, Hiyō and Ryūjō) joined by the BatDiv 2’s Hiei, Kirishima, and the seaplane tender Chitose plus the cruisers Atago, Maya, Takao, Nagara. Soon, they will take part in the Battle of the Eastern Solomons. On 24 August 1942, CruDiv 7 (Kumano and Suzuya) joined the “reinforcement fleet” when the next morning a Consolidated PBY Catalina spots IJN Ryūjō, attacked by USS Enterprise’s planes, but missed.

Meanwhile, Seven floatplanes from Tone and Chikuma are launched to try to locate the US fleet. It’s a Chikuma floatplanes that did it, but is shot down before reporting. A second is more successful. This enable the Kido Butai to launch an air strike focusing on USS Enterprise, which is assumed sunk. In the meantime the reverse is true and the US air strike sunk IJN Ryūjō (from Saratoga AG). Tone in the escort is also attacked, but unsuccessfully by two Avengers: Their Mark 13 torpedoes missed. She is soon able to return to Truk.

Battle of Santa Cruz

By October 1942, Tone patrolled north of the Solomon Islands, expecting the recapture of Henderson Field and on the 19th, escorted by IJN Teruzuki she is detached for an independent mission, trying to locate the US fleet. For the first time she really plays the role intended for her and her sister since 1936. She found nothing and is reunited with her sister off the Santa Cruz Islands. There, as usual at dawn tboth launched their reconnaissance air group, but meanwhile a Kawanishi H6K “Emily” from Jaluit Atoll sighted a carrier off the New Hebrides. On the 26th, 250 miles (400 km) northeast of Guadalcanal, Rear Admiral Hiroaki Abe orders another flotplane recce flight of seven to scout south of Guadalcanal, which succeeded to locate the US fleet. Abe then ordered an air strike, suceeding in sinking USS Hornet (Tokyo is avenged), also damaging USS South Dakota and the cruiser USS San Juan. However, two of the four aircraft launched by Tone during the attack were shot down.

The battle being over, Tone returned to the Guadalcanal area, supporting Japanese reinforcement efforts until mid-November 1942. She was next assigned to patrols from Truk in January and mid-February 1943. After returning home, Maizuru Yard, for a refit on 21 February, rearmed and given a radar, she was back in operations with CruDiv 8 on 15 March 1943, under orders of Rear Admiral Kishi Fukuji, in Truk. On 17 May, Chikuma and Tone escorted IJN Musashi back to Tokyo for the state funeral of Admiral Isoroku Yamamoto.

Back in Truk by 15 July, Tone went on patrolling these waters, several times ambushed by US submarines but always missed. From July to November 1943 she was detached also to take part in many troop transport runs to Rabaul. She kept ptrolling the Marshall Islands and took part in the unsuccesful chase of the American fleet which attacked there. She was back in Kure on 6 November for a refit, with extra modifications. After post-refit sea trials and training in home waters in January, her captian learned that CruDiv 8 was disbanded since the 1st. From ow one, the inseparable sister were reunited in CruDiv 7, also comprising the Mogami-class IJN Suzuya and Kumano, all four under Rear Admiral Shoji Nishimura. Tone was back in Truk on 2 January and in February, assisted with the evacuation of the Palau islands.

On 1st March 1944, she was assigned to commerce raiding in the Indian Ocean and on 9 March, she her floatplanes spotted, and she raced to sink the British freighter SS Behar. She still took aborad some 108 survivors, against orders to leave them at sea, showing the captain’s humane qualities, something rare in the IJN. 32 survivors were disembarked as POW in Batavia. Meanwhile, Admiral Naomasa Sakonju (flagship IJN Aoba), ordered that the remaining prisoners be “disposed of”, beheaded at sea. (Which led after Tokoy’s trials to Sakonju execution for war crimes). Captain Haruo Mayazumi, still, was sentenced to seven years imprisonment. On 20 March 1944, RADM Kazutaka Shiraishi took command of CruDiv 7 while Tone was back in Truk.

Battle of the Philippine Sea

Tone resupplying from a fleet oiler in 1944

On 13 June 1944, Admiral Soemu Toyoda ordered the start of “Operation A-GO”, the defense of the Mariana Islands. Tone was assigned to Force “C” (Ozawa’s Mobile Fleet), and was in the Visayan Sea before heading to the Philippine Sea, heading for Saipan. On 20 June Haruna, Kongō, Chiyoda were attacked by USS Bunker Hill, Monterey and Cabot. The Japanese air cover was destroyed in the “Great Marianas Turkey Shoot”. The battle was lost.

IJN Tone retired with to Okinawa and returned to Kure. She stayed there for a refit on 26 June-8 July 1944, with more AA and radars added. She ferried roops to Okinawa, and was reassigned to Singapore in July, now the ideal place to resupply the oil-hungry IJN cruisers.

Battle of Leyte Gulf

On 23 October 1944, she was assigned with IJN Kumano, Suzuya and her sister ship Chikuma. She left Brunei with Admiral Takeo Kurita’s First Mobile Striking Force, but as they proceed, the fleet was attacked by ambushing Gato and Tench class submersibles in the Palawan Passage. Atago and Maya were sunk, Takao badly damaged, leaving her namesake class gutted. Entering the Sibuyan Sea on 24 October, the Center Force was struck by eleven raids from TG 38.2.

Musashi was sunk, IJN Tone in her escort this time was not spared: She was targeted by scores of Avengers, and even dodging by turning hard over, the USN tactic of pincer attacks worked and she was hit by bombs. At Samar later it was turn of Yamato, Nagato, Haruna and Myōkō to be damaged while attacking Taffy 3 and retire. Tone then attacked USS Heermann but could not get passed a fierce air attack, as damaged again, and she escaped back through the San Bernardino Strait without further damage, but Tone’s sister ship Chikuma was lost, along with the cruisers Chōkai and Suzuya.

The end in Japanese waters

Tone under attack in 1945

On 6 November 1944, Tone departed Brunei towards Manila, but was rerouted to Mako in the Pescadores, before arriving in Japan, entering Kure and the dry dock in Maizuru. There, she received extra AA and a Type 22 radar. However her unit, CruDiv 7 was disbanded on 21 November. She was reassigned to CruDiv 5, with IJN Kumano. From 18 February 1945, she was sent to Etajima, moored there due to the shortage of oil, acting as a training ship. There was a first air raid on 19 March where she was slightly damaged, but repaired anyway. She returned to Kure.

The wreck of Tone in August 1945. Note the camoufage, well visible on her main B turret here.

On 24 July 1945, TF 38 launched the largest air strike against Kure of the war. The goal was to finish off what remained of the IJN. 9 torpedo bombers from USS Monterey targeted IJN Tone, totally immobile. She was quickly hit three bombs and several near-missed which shooked her to the core. Her hull fractures, with much flooding, she sunk and settled to the bottom, a part of her still above water and able to deliver still some AA fire. Due to this, she was attacked again on 28 July, this time by Corsairs and Hellcats loaded with rockets and AP bombs dropped coming from the USS Wasp, Bataan and Ticonderoga. This destroyed her completely. Struck on 20 November 1945, her remains were removed in 1947–1948.

The downfall: A camouflaged IJN Tone at Etajima, July, 29, 1945. She was badly damaged by an air raid on the 24th and finish off by another the day before this photo was taken. colorized by irootoko jr.

IJN Chikuma

IJN Chikuma was completed at Mitsubishi on 20 May 1939 and asigned to CruDiv6 (or “Sentai 6”), Second Fleet later to be renamed as CruDiv8 in November 1939. She took part in initial training, gunnery drills, shakedown cruise and then regular combat exercises in Japanese home waters? It seems unlike he sister Tone she did operate off southern China on three occasions, between March 1940 and March 1941. In late 1941, she trained with Tone in ordeer to play their part in the attack on Pearl Harbor, launching each one Aichi E13A1 “Jake” floatplane for weather reconnaissance over Oahu befire the attack.

Chikuma in 1941
Chikuma in 1941

This was completed by sending a flight of Nakajima E4N2 Type 90-2 Reconnaissance Seaplane as pickets south of the Striking Force. Nine anchored American battleships were reported. By 16 December, CruDiv 8 took part in the second attempted invasion of Wake Island. Chikuma lost one flotplane to AA but the crew was rescued. After some time in Kure, on 14 January 1942 she departed for the Caroline Islands, covering landings at Rabaul in New Britain and like her sister supported the attacks on Lae and Salamaua in New Guinea followed by the Admiralty Islands.

The US raid on Kwajalein led to an unsuccessful pursuit in which she took part. Next, she also took part in the Raid on Port Darwin in Australia, on 19 February, and started operations linked to the Japanese invasion of Java. On 1 March 1942 a floatplane located the 8,806-ton Dutch freighter Modjokerto from Tjilatjap and both sisters escorted by Kasumi and Shiranui intercepted and sank her. They also later spotted USS Edsall, which was finished off by Chikuma from 11 miles (18 km), but missing. Hiei and Kirishima joined in, but Edsall’s Captain managed to dodge all their 297 14-inch, and 132 6-inch shells plus the 844 8-inch and 62 5-inch rounds from the cruisers. More so, when the range closed, she fired her 4-inch guns at Chikuma. Eventually, the combined fire added to dive bombers from Sōryū and Akagi crippled her, before she was finished off by Chikuma.

On 4 March, Chikuma also sank the 5,412-ton Dutch merchant Enggano and a day later, her floatplanes loaded with bombs took part in the attack on Tjilatjap. After the surrender of the Dutch East Indies, she was resupplied and prepared for the raid in the Indian Ocean. It started on 5 April 1942. CruDiv 8 covered the Kido Butai, launching 315 aircraft on Colombo. Later they claimed HMS Cornwall and Dorsetshire. Next an air raid hit Trincomalee. Later HMS Hermes and her escort HMAS Vampire, the corvette HMS Hollyhock, an oiler and a depot ship were spotted and sunk at sea. The fleet went home by mid-April 1942, but they immediately tried to catch TF 16.2 after the Doolittle Raid.

Like Tone, Chikuma also took part in “Operation Mi”, which eveolved into the Battle of Midway. CruDiv 8 was under supreme command of VADM Nagumo’s Carrier Striking Force and on 4 June, both launched their Aichi E13A1 “Jake” on a 300 miles (480 km) area in search of the US carriers. Tone’s aircraft spotted them but failed to identify this as carrier group. Chikuma’s floatplanes found USS Yorktown, shadowed for three hours. Crucialy, this allowed to guiding the D3A “Val” that sunk the carrier in the evening. Two other floatplanes from Chikuma still kept an eye on the bruning Yorktown through the night, but lost one. They directed the I-168 which finished off Yorktown in the morning.

Chikuma and Tone were detached to support VADM Boshiro Hosogaya’s Aleutian invasion force but arrived for nothing and after cruising these cold waters, returned to Ominato on 24 June. RADM Chuichi Hara took command of CruDiv 8 from July and both sisters were sent to take part in the invasion of Guadalcanal, and on 16 August hoined the Kido Butai, two battleships and four cruisers in what became the Battle of the Eastern Solomons. On 24 August 1942, they launched Seven floatplanes which located the US fleet. It’s one of Chikuma’s that reported it, but it was delayed, like at Midway. Soon USS Enterprise was badly damaged and the Japanese objective of deleting all US carriers remaining in activity was never so close. Ryūjō was sunk by USS Saratoga however. Chikuma afterwards was based in Truk.

Chikuma under air attacks at Sant Cruz, 26 October 1942

Next towards the end of the year, she patrolled north of the Solomon Islands, but on 26 October 1942, RADM Hiroaki Abe’s task force launched seven floatplanes to try to see the US fleet south of Guadalcanal, duly located, and followed by an air raid that sunk USS Hornet, damaging USS South Dakota and San Juan. Chikuma in returned had to dodge several Douglas SBD Dauntless from Hornet. Knowing what happened on other cruisers, they fire their torpedoes just before a 500 lb (230 kg) bomb hit precisely her starboard forward torpedo room. If the “long lance” had been stacked her, the explosion would have probably broke her in two. She was also hit by two other bombs. One floatplane and its catapult were blast away at sea. All in all, she suffered 190 killed and 154 wounded, including Captain Komura.

IJN Chikuma, escorted by IJN Urakaze and Tanikaze managed to make it to Truk for emergency repairs. Her machinery was still in good order, but her hull and superstructures had been badly damaged. Next, she sailed back to Kure with the also damaged carrier IJN Zuihō during the battle. Repairs were added to a refit and modernization, with AA and radar, complete by 27 February 1943.

Chikuma’s main artillery in action

On 15 March 1943 RADM Kishi Fukuji took command of CruDiv 8, and she was back to Truk and on 17 May, covered IJN Musashi back to Tokyo,carrying the body of Admiral Yamamoto for state funerals. IJN Chikuma was back in Truk by 15 July and like her sister, dodges several submersibles ambushes along the way. Until November, she perform troop transport runs to Rabaul and patrols in the Marshalls. On 5 November 1943 while refuelling in Rabaul she was attack like her sister by a combined raid of 97 planes from Saratoga and Princeton. A single SBD only managed to make a near-miss, and minor damage. She was in Kure on 12 December. CruDiv 8 was disbanded on 1 January 1944, now both cruisers were reassigned to CruDiv 7 with Suzuya and Kumano (RADM Shoji Nishimura). She was in Singapore by 13 February, Batavia on 15 March to be sent for a raid in the Indian Ocean with her sister. On 20 March 1944, RADM Kazutaka Shiraishi replaced Nishimura and made Chikuma his flagship.

On 13 June 1944, a large operation was launched to defend the Mariana Islands, and Chikuma was part of Force “C” (VADM Ozawa, Mobile Fleet), going via the Philippine Sea towards Saipan. On 20 there was an air attack on the fleet by Bunker Hill, Monterey and Cabot, while “Great Marianas Turkey Shoot” claimed what left of the Kido Butai’s veteran airmen. Chikuma soon retired to Okinawa, ferrying troops. After ferrying army troops to Okinawa, she was reassigned to Singapore in July as flagship, CruDiv 4. Next (and last), she took part in the Battle of Leyte Gulf, meeting here fate:

On 23 October 1944, Chikuma led CruDiv 4 (+Kumano, Suzuya and Tone) from Brunei towards the Philippines under VADM Takeo Kurita’s First Mobile Striking Force. In the Palawan Passage, Atago and Maya were sunk by submarines, Takao damaged, leaving her unit one of the last heavy cruisers engaged. At Sibuyan Sea Musashi was sunk and Myōkō, Nagato and Haruna badly damaged. But it’s on the 25 October off Samar that Chikuma, part of the force engaging Taffy 3, a seemingly easy target, tried to sunk US aircraft carriers, and co-claimed USS Gambier Bay.

Chikuma under bombs
Chikuma under bombs, dodging attacks at Leyte

However she had to retired, harrassed by USS Heermann, combind to fierce air attack, in which even fighters were involved. IJN Chikuma however crippled Heermann until four TBM Avenger torpedo-bombers, led by Lt. Richard Deitchman (USS Manila Bay) lodged a Mk13 torpedo on her stern port quarter. The blast was enough to sever her stern, disabling her port screw, and rudder. Crippled, Chikuma was now circling at 18 knots (33 km/h) and down to 9 knots.

At 11:05, five other TBMs, from USS Kitkun Bay hit her portside amidships, with two torpedoes which cracked ipen her hull and rapidly flooded her engines rooms. At 14:00, slowed down to a crawl, she was attacked by three TBMs from USS Ommaney Bay and Natoma Bay, led Lt. Joseph Cady. They managed to sent two torpedoes on her portside. IJN Nowaki took off survivors, but there are conflicting sources of hown she was scuttled by her or sunk due to the air attacks. But the survivors’s respite was short: The following day, Nowaki was sunk by gunfire from USS Vincennes, Biloxi and Miami and three destroyers, sinking 65 miles (105 km) SSE of Legaspi in the Philippines, she took with her 1,400 men, all of Chikuma’s survivors. The sole survivor in fact of the cruiser was not picked off by her previously and simply drifted ashore to safety. She was officially stricken on 20 April 1945.

Hōshō (1921)
Tenryū class cruisers (1918)

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