The were built for the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Both ships of the class were originally laid down as luxury passenger liners before being acquired by the IJN for conversion to aircraft carriers in 1941. Junyō was the first of the sisters

Sister ship

A sister ship is a ship of the same class as, or of virtually identical design to, another ship. Such vessels share a near-identical hull and superstructure layout, similar displacement, and roughly comparable features and equipment...

 to be completed in May 1942 and the ship participated in the invasion of the Aleutian Islands

Battle of the Aleutian Islands

The Aleutian Islands Campaign was a struggle over the Aleutian Islands, part of Alaska, in the Pacific campaign of World War II starting on 3 June 1942. A small Japanese force occupied the islands of Attu and Kiska, but the remoteness of the islands and the difficulties of weather and terrain meant...

 the following month. Both ships participated in several battles during the Guadalcanal Campaign

Guadalcanal campaign

The Guadalcanal Campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by Allied forces, was a military campaign fought between August 7, 1942 and February 9, 1943 on and around the island of Guadalcanal in the Pacific theatre of World War II...

 in late 1942. Their aircraft were disembarked several times and used from land bases in a number of battles in the South West Pacific

South West Pacific theatre of World War II

The South West Pacific Theatre, technically the South West Pacific Area, between 1942 and 1945, was one of two designated area commands and war theatres enumerated by the Combined Chiefs of Staff of World War II in the Pacific region....

.

Hiyō was torpedoed in June 1943 and Junyō in November; both ships spent about three months under repair. They spent most of the time after their repairs, training and ferrying aircraft before returning to combat. Hiyō was sunk by a gasoline

Gasoline

Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 vapor explosion caused by an American torpedo

Torpedo

The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 hit during the Battle of the Philippine Sea

Battle of the Philippine Sea

The Battle of the Philippine Sea was a decisive naval battle of World War II which effectively eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War...

 in mid-1944 while Junyō was damaged by several bombs. Lacking aircraft, she was used as a transport in late 1944 and was torpedoed in December. The ship was under repair until March 1945 when the repairs were deemed uneconomical. Junyō was then effectively hulk

Hulk (ship)

A hulk is a ship that is afloat, but incapable of going to sea. Although sometimes used to describe a ship that has been launched but not completed, the term most often refers to an old ship that has had its rigging or internal equipment removed, retaining only its flotational qualities...

ed for the rest of the war. The ship was deemed not worth the cost to repair by the Americans after the surrender of Japan in September and she was broken

Ship breaking

Ship breaking or ship demolition is a type of ship disposal involving the breaking up of ships for scrap recycling. Most ships have a lifespan of a few decades before there is so much wear that refitting and repair becomes uneconomical. Ship breaking allows materials from the ship, especially...

 up in 1946–47.

Design and description

The ships were ordered as the fast luxury passenger liners Izumo Maru and Kashiwara Maru by Nippon Yusen Kaisha (Japan Mail Steamship Company-NYK) in late 1938. In exchange for a 60% subsidy of their building costs by the Navy Ministry, they were designed to be converted to an aircraft carrier. To facilitate this process, they were fitted with a double hull, additional fuel oil capacity, provisions for the fitting of additional transverse and longitudinal bulkhead

Bulkhead (partition)

A bulkhead is an upright wall within the hull of a ship or within the fuselage of an airplane. Other kinds of partition elements within a ship are decks and deckheads.-Etymology:...

s, installation of a longitudinal bulkhead to separate the turbine rooms, a strengthened main deck

Deck (ship)

A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...

, more height between decks, rearrangement of the superstructure and passenger accommodations to facilitate the installation of aircraft elevators and hangar

Hangar

A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...

s, more space for additional wiring, installation of a bulbous bow and the addition of aviation gasoline storage tanks fore and aft of the machinery spaces. NYK was only interested in a maximum speed of 24 knots (13.1 m/s) to save fuel, but the Navy wanted a maximum speed of no less than 25.5 knots (13.9 m/s) so they compromised by limiting the performance of the turbines to 80% of maximum power during peacetime.

The ships had a length of about 219.32 metre overall. They had a beam

Beam (nautical)

The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

 of 26.7 metre and a draft of 8.15 metre. They displaced

Displacement (ship)

A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...

 24150 tonnes (23,768.5 LT) at standard load. Their crew ranged from 1,187 to 1,224 officers and men.

Both ships were fitted with two Mitsubishi-Curtis geared steam turbine

Steam turbine

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

 sets with a total of 56250 shp, each driving a 5.5 metres (18 ft) propeller. Steam was provided by six water-tube boiler

Water-tube boiler

A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes...

s; Junyō had Mitsubishi three-drum boilers that operated at a pressure of 40 kg/cm2 and temperature of 420 °C (788 °F) while Hiyō had Kawasaki-La Mont boilers. Their machinery, designed for merchant service, was over four times heavier that that of the . The ships had a designed speed of 25.5 knots, but both exceeded that by small margins during sea trial

Sea trial

A sea trial is the testing phase of a watercraft . It is also referred to as a "shakedown cruise" by many naval personnel. It is usually the last phase of construction and takes place on open water, and can last from a few hours to many days.Sea trials are conducted to measure a vessel’s...

s. They carried carried 4100 tonnes (4,035.2 LT) of fuel oil

Fuel oil

Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...

 which gave them a range of 11700 nautical miles (21,668.4 km) or more at 18 knots (9.8 m/s).

Flight deck arrangements

The flight deck

Flight deck

The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the...

 was 210.3 metre long and had a maximum width of 27.3 metre. A large island was fitted on the starboard side that was integrated with, for the first time in a Japanese carrier, the ship's funnel

Funnel (ship)

A funnel is the smokestack or chimney on a ship used to expel boiler steam and smoke or engine exhaust. They can also be known in as stacks.-Purpose:...

. This was angled 26° outwards to help keep its exhaust from interfering with flight operations. The ships were designed with two superimposed hangars, each approximately 153 metre long, 15 metre wide and 5 metre high. Each hangar could be subdivided by four fire curtains and they were fitted with fire fighting foam dispensers on each side. The hangars were served by two square elevators with rounded corners, 14.03 metres (46 ft) on each side. The elevators had a maximum capacity of 5000 kilograms (11,023.1 lb) and took 15 seconds to go from the lower hangar to the flight deck. The ships were fitted with electrically operated Kure type model 4 arresting gear with nine cables. They also mounted two Type 3 crash barricades. No aircraft catapult

Aircraft catapult

An aircraft catapult is a device used to launch aircraft from ships—in particular aircraft carriers—as a form of assisted take off. It consists of a track built into the flight deck, below which is a large piston or shuttle that is attached through the track to the nose gear of the aircraft, or in...

 was fitted. The ships mounted a crane

Crane (machine)

A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...

 on the port side of the flight deck, just aft of the rear elevator. When collapsed, it was flush with the flight deck.

Their air group was originally intended to consist of 12 Mitsubishi A5M

Mitsubishi A5M

The Mitsubishi A5M, Japanese Navy designation was "Type 96 carrier-based fighter" was a Japanese carrier-based fighter aircraft. It was the world's first monoplane shipboard fighter and the direct ancestor of the famous Mitsubishi A6M 'Zero'...

 'Claude' fighters, plus four in storage, 18 Aichi D3A

Aichi D3A

The , Allied reporting name "Val") was a World War II carrier-borne dive bomber of the Imperial Japanese Navy . It was the primary dive bomber in the Imperial Japanese Navy, and participated in almost all actions, including Pearl Harbor....

 'Val' dive bombers, plus two in reserve, and 18 Nakajima B5N

Nakajima B5N

|-See also:-References:NotesBibliography* Bridgwater, H.C. and Peter Scott. Combat Colours Number 4: Pearl Harbor and Beyond, December 1941 to May 1942. Luton, Bedfordshire, UK: Guideline Publications, 2001. ISBN 0-9539040-6-7....

 'Kate' torpedo bomber

Torpedo bomber

A torpedo bomber is a bomber aircraft designed primarily to attack ships with aerial torpedoes which could also carry out conventional bombings. Torpedo bombers existed almost exclusively prior to and during World War II when they were an important element in many famous battles, notably the...

s. This was revised to substitute a dozen Mitsubishi A6M Zero fighters, and three in storage for the A5Ms by the time the ship commissioned in 1942. As a result of the lessons learned from the Battle of Midway

Battle of Midway

The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

 in June, the ships' fighter complement was strengthened to 21 Zeros, and the other aircraft reduced to 12 D3As and 9 B5Ns. By the end of the year, six more Zeros replaced an equal number of D3As. Although it was possible to fit all these aircraft into the hangars, eight or nine were usually stored on the flight deck to reduce cramping below decks.

Armor, armament and sensors

As a conversion from a ocean liner, it was not possible to add much armor, although the ships had a double hull. Two plates of Ducol steel, each 25 mm (0.984251968503937 in) thick, protected the sides of the ship's machinery spaces. The ship's aviation gasoline tanks and magazine

Magazine (artillery)

Magazine is the name for an item or place within which ammunition is stored. It is taken from the Arabic word "makahazin" meaning "warehouse".-Ammunition storage areas:...

s were protected by one layer of Ducol steel. In addition, her machinery spaces were further subdivided by transverse and longitudinal bulkheads to limit any flooding.

The primary armament consisted of a dozen 40-caliber

Caliber (artillery)

In artillery, caliber or calibredifference in British English and American English spelling is the internal diameter of a gun barrel, or by extension a relative measure of the length....

 12.7 cm Type 89

12.7 cm/40 Type 89 naval gun

The 12.7 cm/40 Type 89 naval gun was a Japanese anti-aircraft gun introduced before World War II. It was the Imperial Japanese Navy's standard heavy AA gun during the war.-External links:*...

 anti-aircraft

Anti-aircraft warfare

NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 (AA) guns in twin mounts on sponson

Sponson

Sponsons are projections from the sides of a watercraft, for protection, stability, or the mounting of equipment such as armaments or lifeboats, etc...

s along the sides of the hull. They fired 23.45 kilograms (51.7 lb) projectiles at a rate between 8 and 14 rounds per minute at a muzzle velocity

Muzzle velocity

Muzzle velocity is the speed a projectile has at the moment it leaves the muzzle of the gun. Muzzle velocities range from approximately to in black powder muskets , to more than in modern rifles with high-performance cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns...

 of 700–725 m/s (2,296.6–2,378.6 ft/s); at 45°, this provided a maximum range of 14800 metres (16,185.5 yd), and a maximum ceiling of 9400 metres (30,839.9 ft). The ships were also initially equipped with eight triple 25 mm Type 96 light AA guns, also in sponsons along the sides of the hull. They fired 0.25 kilogram (0.551155655462194 lb) projectiles at a muzzle velocity

Muzzle velocity

Muzzle velocity is the speed a projectile has at the moment it leaves the muzzle of the gun. Muzzle velocities range from approximately to in black powder muskets , to more than in modern rifles with high-performance cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns...

 of 900 m/s (2,952.8 ft/s); at 50°, this provided a maximum range of 7500 metres (8,202 yd), and an effective ceiling of 5500 metres (18,044.6 ft). The maximum effective rate of fire was only between 110 and 120 rounds per minute due to the frequent need to change the fifteen-round magazines. In mid-1943, four more triple mounts were added and another four triple mounts in late 1943–early 1944. Two of these last four mounts were mounted on the stern and the others were placed in front of and behind the island. A dozen single mounts were also added, some of which were portable and could be mounted on tie-down points on the flight deck. After the Battle of the Philippine Sea in June 1944, Junyōs anti-aircraft armament was reinforced with three more triple mounts, two twin mounts and 18 single mounts for the 25 mm Type 96 gun. These guns were supplemented by six 28-round AA rocket launchers. Each 12 centimetres (4.7 in) rocket weighed 22.5 kilograms (49.6 lb) and had a maximum velocity of 200 m/s (656.2 ft/s). Their maximum range was 4800 metres (5,249.3 yd). In October 1944, Junyō had a total of 91 25 mm barrels; 57 in 19 triple mounts, four in two twin mounts, and 30 single mounts.

Two Type 94 high-angle fire-control directors, one on each side of the ship, were fitted to control the Type 89 guns. Each director mounted a 4.5 metre rangefinder

Rangefinder

A rangefinder is a device that measures distance from the observer to a target, for the purposes of surveying, determining focus in photography, or accurately aiming a weapon. Some devices use active methods to measure ; others measure distance using trigonometry...

. When Junyō first commissioned only the rangefinders were fitted and the directors were added later. Four Type 95 directors controlled the 25 mm guns and another pair were added in early 1943. Early warning was provided by two Type 2, Mark 2, Model 1 air search radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

s. The first of these was mounted on the top of the island in mid- to late 1942 on each ship, and the other was added during 1943. This latter system was fitted on the port side of the hull, outboard of the rear elevator. A smaller Type 3, Mark 1, Model 3 air search radar was added in 1944 on Junyō.

Ships

Ship	Original name	Builder	Laid down	Launched	Commissioned	Fate
(飛鷹)	Izumo Maru	Kawasaki Heavy Industries Kawasaki Heavy Industries is an international corporation based in Japan. It has headquarters in both Chūō-ku, Kobe and Minato, Tokyo.The company is named after its founder Shōzō Kawasaki and has no connection with the city of Kawasaki, Kanagawa....  Shipyard, Kobe Kobe , pronounced , is the fifth-largest city in Japan and is the capital city of Hyōgo Prefecture on the southern side of the main island of Honshū, approximately west of Osaka...	30 November 1939	24 June 1941	31 July 1942	Sunk 21 June 1944 during the Battle of the Philippine Sea Battle of the Philippine Sea The Battle of the Philippine Sea was a decisive naval battle of World War II which effectively eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War...
(隼鷹)	Kashiwara Maru	Mitsubishi Heavy Industries Mitsubishi Heavy Industries , or MHI, is a Japanese company. It is one of the core companies of Mitsubishi Group.-History:In 1870 Yataro Iwasaki, the founder of Mitsubishi took a lease of Government-owned Nagasaki Shipyard. He named it Nagasaki Shipyard & Machinery Works, and started the shipbuilding business on a full scale...  Shipyard, Nagasaki Nagasaki is the capital and the largest city of Nagasaki Prefecture on the island of Kyushu in Japan. Nagasaki was founded by the Portuguese in the second half of the 16th century on the site of a small fishing village, formerly part of Nishisonogi District...	20 March 1939	26 June 1941	3 May 1942	Scrapped, 1946–47

Service history

The ships were purchased on 10 February 1941 by the Navy Ministry for the price of ¥48,346,000 and their armament and aircraft cost an additional ¥27,800,000. The cost to convert the two ships was budgeted at ¥38,073,000, for a grand total of ¥114,219,000. Kashiwara Maru and Izumo Maru were temporarily referred to as No. 1001 Ship (Dai 1001 bankan) and No. 1002 Ship respectively to keep their conversions secret. Junyō was initially classified as an auxiliary aircraft carrier (Toketsetsu kokubokan), but following the loss of four Japanese fleet carriers in the Battle of Midway

Battle of Midway

The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

, she was redesignated as a regular carrier (Kokubokan) in July; Hiyō, completed after the loss of the carriers, received that designation from the beginning.

Despite being launched several days after Hiyō, Junyō was the first of the pair to be commissioned in May 1942. She was assigned to the Fourth Carrier Division

Fourth Carrier Division

The was a seaplane tender and aircraft carrier unit of the Imperial Japanese Navy's Combined Fleet.-Organization:-Commander:-Bibliography:*"Monthly The Maru" series, and "The Maru Special" series,...

 of the 1st Air Fleet, together with . The ship was tasked to support the invasion of the Aleutian Islands, a diversionary thrust in support of the attack on Midway

Battle of Midway

The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

. Junyō carried 18 A6M2 Zeros and 18 D3As for this operation. The ship launched her first airstrike at dawn on 3 June against Dutch Harbor

Battle of Dutch Harbor

The Battle of Dutch Harbor took place on 3-4 June 1942, and was a minor air and naval battle of the Aleutian Islands Campaign of World War II between Imperial Japanese Navy and United States Army and Navy forces.-Overview:...

 on Unalaska Island

Unalaska Island

Unalaska is an island in the Fox Islands group of the Aleutian Islands in the U.S. state of Alaska, at . The island has a land area of . The city of Unalaska, Alaska, covers part of the island and all of neighboring Amaknak Island where the Port of Dutch Harbor is located...

. She accomplished little during this operation, losing five aircraft to all causes, and her own aircraft only shot down five American aircraft.

Upon arrival at Truk

Chuuk

Chuuk — formerly Truk, Ruk, Hogoleu, Torres, Ugulat, and Lugulus — is an island group in the south western part of the Pacific Ocean. It comprises one of the four states of the Federated States of Micronesia , along with Kosrae, Pohnpei, and Yap. Chuuk is the most populous of the FSM's...

 on 9 October, the two sisters were assigned to the Second Carrier Division

Second Carrier Division

was an aircraft carrier unit of the Imperial Japanese Navy's First Air Fleet. At the beginning of the Pacific Campaign of World War II, the Second Carrier Division consisted of the fleet carriers Sōryū and Hiryū...

 to begin operations against American forces in the Guadalcanal area as part of the 3rd Fleet. On 15 October, the two carriers reached the vicinity of Malaita Island in the Solomon Islands

Solomon Islands

Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

 and their aircraft discovered a resupply convoy for Guadalcanal

Guadalcanal

Guadalcanal is a tropical island in the South-Western Pacific. The largest island in the Solomons, it was discovered by the Spanish expedition of Alvaro de Mendaña in 1568...

 that was escorted by the destroyer . Their aircraft attacked and sank the destroyer. The next day, they found the small seaplane tender

Seaplane tender

A seaplane tender is a ship that provides facilities for operating seaplanes. These ships were the first aircraft carriers and appeared just before the First World War.-History:...

, , in Lunga Roads offloading avgas

Avgas

Avgas is an aviation fuel used to power piston-engine aircraft. Avgas is distinguished from mogas , which is the everyday gasoline used in cars and some non-commercial light aircraft...

 into barges. Dive bombers from the sisters blew the ship's stern off, but failed to sink McFarland. The two carriers were intended to play a prominent role in the Japanese effort to retake Guadalcanal Island and were assigned to the Advance Force for this operation. Their aircraft were supposed to provide air cover after the Japanese night attack that retook Henderson Field

Henderson Field

Henderson Field is the name of several airports:* Henderson Field on Guadalcanal Island in the Solomon Islands, renamed to Honiara International Airport in 2003....

 and then they were to be flown ashore, but Hiyōs machinery problems caused her to return to Truk. Some of her aircraft were transferred to her sister before she departed.

In late October 1942, during the Guadalcanal Campaign, Junyō took part in the Battle of the Santa Cruz Islands

Battle of the Santa Cruz Islands

The Battle of the Santa Cruz Islands, 26 October 1942, sometimes referred to as the Battle of Santa Cruz or in Japanese sources as the , was the fourth carrier battle of the Pacific campaign of World War II and the fourth major naval engagement fought between the United States Navy and the Imperial...

. At this time, her air group consisted of 18 Zeros, 18 D3As and nine B5Ns. Her aircraft made hits on the carrier , the battleship

Battleship

A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

  and the light cruiser

Light cruiser

A light cruiser is a type of small- or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck...

 , but inflicted little substantial damage. A torpedo hit from one of her B5Ns, however, did force the Americans to abandon their effort to repair Hornet. During this time, Hiyōs remaining aircraft flew to Rabaul

Rabaul

Rabaul is a township in East New Britain province, Papua New Guinea. The town was the provincial capital and most important settlement in the province until it was destroyed in 1994 by falling ash of a volcanic eruption. During the eruption, ash was sent thousands of metres into the air and the...

 on 23 October where they provided air cover for Japanese forces on Guadalcanal. A detachment from the air group was transferred to Buin, Papua New Guinea

Buin, Papua New Guinea

Buin is a settlement at the southern end of the island of Bougainville, a part of the North Solomons Province, located in the northern Solomon Islands in the South Pacific Ocean.-History:...

 on 1 November and participated in the Naval Battle of Guadalcanal

Naval Battle of Guadalcanal

The Naval Battle of Guadalcanal, sometimes referred to as the Third and Fourth Battles of Savo Island, the Battle of the Solomons, The Battle of Friday the 13th, or, in Japanese sources, as the , took place from 12–15 November 1942, and was the decisive engagement in a series of naval battles...

 later in the month. Those aircraft that remained at Rabaul flew back to Truk by 11 November, but the Buin detachment was ferried back to Japan on 14 December.

In mid-November 1942, Junyō was tasked to provide air cover for the convoy bringing reinforcements for the Japanese forces on Guadalcanal during the three-day-long Naval Battle of Guadalcanal

Naval Battle of Guadalcanal

The Naval Battle of Guadalcanal, sometimes referred to as the Third and Fourth Battles of Savo Island, the Battle of the Solomons, The Battle of Friday the 13th, or, in Japanese sources, as the , took place from 12–15 November 1942, and was the decisive engagement in a series of naval battles...

. The ship's fighters were unable to do so; seven transports were sunk and the remaining four transports were damaged. In December 1942 – January 1943, the carrier covered several convoys that brought reinforcements to Wewak

Wewak

Wewak is the capital of the East Sepik province of Papua New Guinea. It is located on the northern coast of the island of New Guinea. It is the largest town between Madang and Jayapura. It is the see city of the Roman Catholic Diocese of Wewak....

, New Guinea

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and her air group was based there for several days to protect the forces there before returning to Truk on 20 January. The ship then covered the evacuation of forces from Guadalcanal through early February.

Hiyō had returned to Japan in December and Junyō followed in February. Both ships returned to Truk in late March and their air groups were detached from in early April to participate in Operation I-Go

Operation I-Go

was an aerial counter-offensive launched by Imperial Japanese forces against Allied forces during the Solomon Islands and New Guinea Campaigns in the Pacific Theater of World War II from 1–16 April 1943...

, a land-based aerial offensive against Allied bases in the Solomon Islands

Solomon Islands

Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

 and New Guinea

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

. The ships returned to Japan in late May and sailed for Truk on 7 June, but Hiyō was torpedoed that evening and forced to return to port for repairs. Her fighters were flown to Truk by 15 July and assigned to the light carrier . The ship was under repair at Yokosuka until 15 September. Junyōs air group was deployed to Buin, Papua New Guinea

Buin, Papua New Guinea

Buin is a settlement at the southern end of the island of Bougainville, a part of the North Solomons Province, located in the northern Solomon Islands in the South Pacific Ocean.-History:...

 on 2 July in response the American invasion of Rendova Island

Rendova Island

Rendova Island is an island, part of the New Georgia Islands of Solomon Islands in the South Pacific, east of Papua New Guinea. There are two indigenous languages spoken on Rendova Island: the Austronesian language Ughele in the north, and the Papuan language Touo in the south.The black-sand...

 on 30 June. Leaving her aircraft behind, the carrier returned to Japan in late July.

Junyō ferried aircraft to Singapore

Singapore

Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

 in mid-August and troops and equipment to the Caroline Islands

Caroline Islands

The Caroline Islands are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically they are divided between the Federated States of Micronesia in the eastern part of the group, and Palau at the extreme western end...

 the following month. On 5 November 1943, she was hit by a torpedo, but the damage was light, other than the disabled rudder. The ship was under repair and refit until 29 February 1944 at Kure

Kure, Hiroshima

is a city in Hiroshima prefecture, Japan.As of October 1, 2010, the city has an estimated population of 240,820 and a population density of 681 persons per km². The total area is 353.74 km².- History :...

. The air groups of both carriers were reconstituted at Singapore on 1 November. The aircraft transferred to Truk on 1 December and then to Kavieng

Kavieng

Kavieng is the capital of the Papua New Guinean province of New Ireland and the largest town on the island of the same name. The town is located at Balgai Bay, on the northern tip of the island. As of 2000, it had a population of 10,600....

 at the end of December before reaching Rabaul on 25 January 1944; the survivors were back at Truk on 20 February and the air group was disbanded.

Hiyō departed Japan for Singapore

Singapore

Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

 on 24 November. She arrived on 3 December and was almost immediately assigned duties as an aircraft ferry until January when the ship returned to Japan. In the meantime, the Japanese Navy had restructured its carrier air groups so that one air group was assigned to one carrier division and Air Group 652 was assigned to the 2nd Carrier Division with Hiyō, Junyō and Ryūhō on 1 March. The air group was last in priority to be rebuilt and only had 30 Model 21 Zeros, 13 Model 52 Zeros and four D3As on hand on 1 April of its authorized 81 fighters, 36 dive bombers and 27 torpedo bombers. The ships conducted training for their aircraft in the Inland Sea until 11 May when she sailed for Tawi-Tawi

Tawi-Tawi

Tawi-Tawi is an island province of the Philippines located in the Autonomous Region in Muslim Mindanao . The capital of Tawi-Tawi is Bongao. The province is the southernmost of the country sharing sea borders with the Malaysian State of Sabah and the Indonesian East Kalimantan province. To the...

 in the Philippines

Philippines

The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

. The new base was closer to the oil wells in Borneo

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 on which the Navy relied and also to the Palau

Palau

Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...

 and western Caroline Islands

Caroline Islands

The Caroline Islands are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically they are divided between the Federated States of Micronesia in the eastern part of the group, and Palau at the extreme western end...

 where the Japanese expected the next American attack. However, the location lacked an airfield on which to train the green pilots and American submarines were very active in the vicinity which restricted the ships to the anchorage.

Battle of the Philippine Sea

The Japanese fleet was en route to Guimares Island in the central Philippines on 13 June, where they intended to practice carrier operations in an area better protected from submarines, when Vice Admiral

Vice Admiral

Vice admiral is a senior naval rank of a three-star flag officer, which is equivalent to lieutenant general in the other uniformed services. A vice admiral is typically senior to a rear admiral and junior to an admiral...

 Jisaburō Ozawa

Jisaburo Ozawa

was an admiral in the Imperial Japanese Navy during World War II. He was the last Commander-in-Chief of Combined Fleet. Many military historians regard Ozawa as one of the most capable Japanese flag officers.-Biography:...

 learned of the American attack on the Mariana Islands

Mariana Islands

The Mariana Islands are an arc-shaped archipelago made up by the summits of 15 volcanic mountains in the north-western Pacific Ocean between the 12th and 21st parallels north and along the 145th meridian east...

 the previous day. Upon reaching Guimares, the fleet refuelled and sortied into the Philippine Sea

Philippine Sea

The Philippine Sea is a marginal sea east and north of the Philippines occupying an estimated surface area of 2 million mi² on the western part of the North Pacific Ocean...

 where they spotted Task Force 58 on 18 June. The Americans failed to locate Ozawa's ships that day and the Japanese turned south to maintain a constant distance between them and the American carriers as Ozawa had decided on launching his air strikes early the following morning. At this time, Air Group 652 consisted 81 Zeros, 27 D3As, 9 Yokosuka D4Y

Yokosuka D4Y

The D4Y Navy Type 2 Carrier Dive bomber was operated by the Imperial Japanese Navy. Its Allied reporting name was "Judy". The D4Y was one of the fastest dive-bombers of the war, and only the delays in its development hindered its service, while its predecessor, the slower fixed gear Aichi D3A...

 "Judy" dive bombers and 18 Nakajima B6N

Nakajima B6N

The Nakajima B6N Tenzan was the Imperial Japanese Navy's standard carrier-borne torpedo bomber during the final years of World War II and the successor to the B5N "Kate"...

 "Jill" torpedo bombers, roughly evenly divided among the three ships. The three carriers launched multiple air strikes against the American ships, but generally failed to locate them and did not inflict any damage while losing most of their aircraft.

At dusk, the Japanese turned away to the northwest to regroup and to refuel and the Americans turned west to close the distance. They discovered the retiring Japanese fleet during the afternoon of the following day and Vice Admiral Marc Mitscher

Marc Mitscher

Admiral Marc Andrew "Pete" Mitscher was an admiral in the United States Navy who served as commander of the Fast Carrier Task Force in the Pacific in the latter half of World War II.-Early life and career:...

 ordered an air strike launched. Hiyō was struck by two bombs, one of which detonated above the bridge and killed or wounded virtually everyone there. More seriously, the ship was struck by one torpedo dropped by a Grumman TBF Avenger from . This knocked out the starboard engine room and started fires, but Hiyō was able to continue, albeit a slower speed. Two hours later, a large explosion occurred when leaking gasoline vapor ignited and it knocked out all power on the ship. The fires raged out of control and Hiyō sank stern first shortly afterwards at 16°20′N 132°32′E. Roughly 1,000 men were rescued by her escorting destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s, but 247 officers and men died aboard the carrier.
Junyō was hit by two bombs near her island. The ship was not badly damaged, but the damage did stop flight operations. Air Group 652 claimed two Grumman F6F Hellcat fighters and nine Grumman TBF Avenger torpedo bombers shot down, but lost 11 aircraft, plus another three that had to ditch

Emergency landing

An emergency landing is a landing made by an aircraft in response to a crisis which either interferes with the operation of the aircraft or involves sudden medical emergencies necessitating diversion to the nearest airport.-Types of emergency landings:...

. By the end of the battle, the air group only consisted of 11 A6M5s, 5 A6M2s and 1 B6N and it was disbanded on 10 July. Most of its remaining personnel were assigned to Air Group 653.

After repairs at Kure, the ship remained in the Inland Sea without aircraft until 27 October when she was tasked to transport material to Borneo

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

. On 3 November, she was attacked by the submarine , but her escorting destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

, , deliberately sacrificed herself by intercepting the torpedoes and sank with no survivors. While returning from Manila

Manila

Manila is the capital of the Philippines. It is one of the sixteen cities forming Metro Manila.Manila is located on the eastern shores of Manila Bay and is bordered by Navotas and Caloocan to the north, Quezon City to the northeast, San Juan and Mandaluyong to the east, Makati on the southeast,...

, Junyō was attacked by the submarines , and early in the morning of 9 December 1944. She was hit by three torpedoes, but she was able to proceed on one engine. She reached Sasebo

Sasebo, Nagasaki

is a city located in Nagasaki Prefecture, Japan. As of 2011, the city has an estimated population of 259,800 and the density of 609 persons per km². The total area is 426.47 km². The locality is famed for its scenic beauty. The city includes a part of Saikai National Park...

 the following day and began repairs on 18 December.

The repairs were abandoned in March 1945 for lack of materials and the ship was moved from the dock to Ebisu Bay, Sasebo on 1 April. Efforts to camouflage the ship began on 23 April and she was reclassified as a guard ship

Guard ship

A guard ship is a warship stationed at some port or harbour to act as a guard, and in former times in the Royal Navy to receive the men impressed for service...

 on 20 June. Junyōs armament was ordered removed on 5 August and the ship was surrendered to the Allies on 2 September. An American technical team evaluated the ship's condition on 8 October and deemed her a constructive total loss. Junyō was stricken from the Navy List

Navy List

A Navy List or Naval Register is an official list of naval officers, their ranks and seniority, the ships which they command or to which they are appointed, etc., that is published by the government or naval authorities of a country....

on 30 November and scrapped between 1 June 1946 and 1 August 1947 by the Sasebo Ship Company.