Japanese aircraft carrier Hiyo
Encyclopedia
Hiyō (Japanese
: 飛鷹 "Flying Hawk") was a of the Imperial Japanese Navy
. Begun as an ocean liner
in 1939, she was purchased by the Navy Ministry
in 1941 for conversion to an aircraft carrier. Completed shortly after the Battle of Midway
in June 1942, she participated in the Guadalcanal Campaign
in October and missed the Battle of the Santa Cruz Islands
later that month because of a generator
fire. Her aircraft were disembarked several times and used from land bases in a number of battles in the South West Pacific
. Hiyō was torpedoed in mid-1943 and spent three months under repair. She spent most of the next six months training and ferrying aircraft before returning to combat. She was sunk by a gasoline
vapor explosion caused by an American torpedo
hit during the Battle of the Philippine Sea
in mid-1944.
Hiyō had a length of 220 metre overall. She had a beam
of 26.7 metre and a draft of 8.15 metre. She displaced
24150 tonnes (23,768.5 LT) at standard load. Her crew ranged from 1,187 to 1,224 officers and men.
The ship was fitted with two Mitsubishi-Curtis geared steam turbine
sets with a total of 56250 shp, each driving a 5.5 metres (18 ft) propeller. Steam was provided by six Kawasaki-La Mont water-tube boiler
s. Her machinery, designed for merchant service, was over four times heavier that that of the . Hiyō had a designed speed of 25.5 knots (13.9 m/s), but during sea trial
s she reached 25.63 knots (14 m/s) from 56630 shp. The ship carried carried 4100 tonnes (4,035.2 LT) of fuel oil
which gave her a range of 11700 nautical miles (21,668.4 km) at 18 knots (9.8 m/s).
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
. This was angled 26° outwards to help keep its exhaust from interfering with flight operations. The ship was designed with two superimposed hangar
s, 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 aircraft 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. Hiyō was fitted with electrically operated Kure type model 4 arresting gear with nine cables. She also mounted two Type 3 crash barricades. No aircraft catapult
was fitted. The ship mounted a crane
on the port side of the flight deck, just aft of the rear elevator. When collapsed, it was flush with the flight deck.
The ship's air group was originally intended to consist of 12 Mitsubishi A5M
'Claude' fighters, plus four in storage, 18 Aichi D3A
'Val' dive bombers, plus two in reserve, and 18 Nakajima B5N
'Kate' torpedo bomber
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
in June, the ship's 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.
s were protected by one layer of Ducol steel. In addition, her machinery spaces were further subdivided by transverse and longitudinal bulkhead
s to limit any flooding.
The ship's primary armament consisted of a dozen 40-caliber
12.7 cm Type 89
anti-aircraft
(AA) guns in twin mounts on sponsons along the sides of the hull. Hiyō was also initially equipped with eight triple 25 mm Type 96 light AA guns, also in sponsons along the sides of the hull. In early 1943, four more triple mounts were added and another four triple mounts late in the year. 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.
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
. 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
s. The first of these was mounted on the top of the island shortly before she was completed in July 1942 and the other was added later in the year. 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.
was laid down by Kawasaki Heavy Industries
Shipyard, Kobe
, on 30 November 1939 with the name of Izumo Maru. The ship was purchased on 10 February 1941 by the Navy Ministry and she was temporarily referred to as No. 1002 Ship (Dai 1002 bankan) to keep her conversion secret. She was launched
on 24 June 1941 and commissioned on 31 July 1942.
The ship was assigned to the Second Carrier Division
of the 1st Air Fleet after commissioning and became Rear Admiral
Kakuji Kakuta
's flagship
on 12 August. After spending the next several months working up, Hiyō arrived at Truk
, together with her sister
, on 9 October 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
and their aircraft discovered a resupply convoy for Guadalcanal
that was escorted by the destroyer . The A6M Zeros and D3As from the sisters attacked and sank the destroyer. The next day, they found the small seaplane tender
, , in Lunga Roads offloading avgas
into barges. Nine D3As attacked, blowing the ship's stern off and destroying the barge. McFarland was not sunk, but required months of repairs. 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
and then they were to be flown ashore. A fire in the generator room occurred on 17 October and reduced her top speed to 16 knots (8.7 m/s) so Admiral Kakuta transferred his flag to Junyō while Hiyō returned to Truk for repairs. Some of her aircraft, however, were also transferred to Junyō before she left.
The remaining aircraft of her air group (16 Zeros and 17 D3As) were flown off for Rabaul 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
on 1 November and participated in the Naval Battle of Guadalcanal
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.
Hiyō spent November in Truk, during which time she was twice slightly damaged by American air raids, before returning to Japan in early December where she was rejoined by the rest of her air group. Aside from a brief refit at Kure from 26 February to 4 March 1943, the ship was training in the Inland Sea until she sailed for Truk on 22 March. Her air group consisted of 27 Zeros and 12 D3As at this time. They were detached from Hiyō in early April to participate in Operation I-Go
, a land-based aerial offensive against Allied bases in the Solomon Islands
and New Guinea
. The carrier was again lightly damaged from bomb splinters on 12 April from an American air attack. After her air group returned, the ship arrived back in Japan on 21 May in case she was needed to relieve Japanese forces fighting on the Attu Island
.
Now the flagship of the Second Carrier Division under Rear Admiral Munetaka Sakamaki, Hiyō and her sister Junyō departed Yokosuka on 7 June en route for Truk. Later that evening, the ship was torpedoed by the submarine off Miyakejima
. Hits in the starboard bow and boiler room knocked out all power, but she managed to return to Japan under her own power the following day. Hiyōs fighters were flown to Truk by 15 July and assigned to the light carrier . The ship was under repair at Yokosuka until 15 September. On 1 November, Hiyōs air group was reconstituted with 24 Zeros, 18 D3As and 9 B5Ns and the ship departed Japan for Singapore
on 24 November. She arrived on 3 December and was almost immediately assigned duties as an aircraft ferry. On 9 December, Hiyō left Singapore en route for Truk with several deliveries on the way. The ship arrived there on 22 December and disembarked her own air group before proceeding on to Saipan
to deliver more aircraft. The air group was transferred to Kavieng
and later Rabaul to provide air cover for Japanese operations there.
Hiyō returned to Japan on 1 January 1944 and her air group rejoined her on 2 March, albeit without aircraft. 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. 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 ship conducted training for her aircraft in the Inland Sea until 11 May when she sailed for Tawi-Tawi
in the Philippines
. The new base was closer to the oil wells in Borneo
on which the Navy relied and also to the Palau
and western Caroline Islands
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.
Jisaburō Ozawa
learned of the American attack on the Mariana Islands
the previous day. Upon reaching Guimares, the fleet refuelled and sortied into the Philippine Sea
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
"Judy" dive bombers and 18 Nakajima B6N
"Jill" torpedo bombers, roughly evenly divided among the three ships. The three carriers began launching their first air strike of 26 bomb-carrying A6M2 Zeros, 16 A6M5 Zeros to escort the other aircraft and seven B6Ns at about 0930. Most of these aircraft were misdirected and failed to find any American ships, although a dozen persisted in their search and found one of the American task groups. Five bomb-carrying Zeros, a B6N and an escort Zero were shot down by the defending fighters and no damage was inflicted on any American ship.
A second air strike of 27 D3As, nine D4Ys, two B6Ns and 26 escorting Zeros was launched around 1100, accompanied by at least 18 A6Ms and B6Ns from and . They had also given given an erroneous spot report and could not find any American ships. The 652nd aircraft headed for airfield at Rota
and Guam
to refuel while those from the other two carriers headed back to them. Six D4Ys and two Zeros bound for Rota spotted the carriers and en route and failed to inflict any damage on the American ships while losing five D4Ys to anti-aircraft fire. Radar had spotted those aircraft headed for Guam and they were intercepted by 41 Grumman F6F Hellcats. Only one A6M5, one D4Y and seven D3As of the 49 Japanese aircraft survived the encounter and landed.
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
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
s, but 247 officers and men died aboard the carrier.
Japanese language
is a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family, which has a number of proposed relationships with other languages, none of which has gained wide acceptance among historical linguists .Japanese is an...
: 飛鷹 "Flying Hawk") was a of 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...
. Begun as an ocean liner
Ocean liner
An ocean liner is a ship designed to transport people from one seaport to another along regular long-distance maritime routes according to a schedule. Liners may also carry cargo or mail, and may sometimes be used for other purposes .Cargo vessels running to a schedule are sometimes referred to as...
in 1939, she was purchased by the Navy Ministry
Ministry of the Navy of Japan
The was a cabinet-level ministry in the Empire of Japan charged with the administrative affairs of the Imperial Japanese Navy . It existed from 1872 to 1945.-History:...
in 1941 for conversion to an aircraft carrier. Completed shortly after 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 1942, she participated in 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 October and missed 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...
later that month because of a generator
Generator
Generator may refer to:* Electrical generator* Engine-generator, an electrical generator, but with its own engine.* Generator , any of several closely related usages in mathematics.Computing:...
fire. Her 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 mid-1943 and spent three months under repair. She spent most of the next six months training and ferrying aircraft before returning to combat. She 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.
Design and description
The ship was ordered as the fast luxury passenger liner Izumo Maru by Nippon Yusen Kaisha (Japan Mail Steamship company) in late 1938. In exchange for a 60% subsidy of her building costs by the Navy Ministry, she was designed to be converted to an aircraft carrier.Hiyō had a length of 220 metre overall. She 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. She 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. Her crew ranged from 1,187 to 1,224 officers and men.
The ship was 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 Kawasaki-La Mont 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. Her machinery, designed for merchant service, was over four times heavier that that of the . Hiyō had a designed speed of 25.5 knots (13.9 m/s), but 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 she reached 25.63 knots (14 m/s) from 56630 shp. The ship 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 her a range of 11700 nautical miles (21,668.4 km) at 18 knots (9.8 m/s).
Flight deck arrangements
Hiyōs flight deckFlight 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 ship was designed with two superimposed 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, 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 aircraft 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. Hiyō was fitted with electrically operated Kure type model 4 arresting gear with nine cables. She 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 ship 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.
The ship's 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 ship's 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 ship 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 magazineMagazine (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 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 to limit any flooding.
The ship's 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 sponsons along the sides of the hull. Hiyō was also initially equipped with eight triple 25 mm Type 96 light AA guns, also in sponsons along the sides of the hull. In early 1943, four more triple mounts were added and another four triple mounts late in the year. 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.
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...
. 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 shortly before she was completed in July 1942 and the other was added later in the year. 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.
Service history
Hiyōs keelKeel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
was laid down by 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...
, on 30 November 1939 with the name of Izumo Maru. The ship was purchased on 10 February 1941 by the Navy Ministry and she was temporarily referred to as No. 1002 Ship (Dai 1002 bankan) to keep her conversion secret. She was launched
Ship naming and launching
The ceremonies involved in naming and launching naval ships are based in traditions thousands of years old.-Methods of launch:There are three principal methods of conveying a new ship from building site to water, only two of which are called "launching." The oldest, most familiar, and most widely...
on 24 June 1941 and commissioned on 31 July 1942.
The ship was 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...
of the 1st Air Fleet after commissioning and became Rear Admiral
Rear Admiral
Rear admiral is a naval commissioned officer rank above that of a commodore and captain, and below that of a vice admiral. It is generally regarded as the lowest of the "admiral" ranks, which are also sometimes referred to as "flag officers" or "flag ranks"...
Kakuji Kakuta
Kakuji Kakuta
, was an admiral in the Imperial Japanese Navy during World War II. He is noted for his role in commanding Japanese naval aviation units in the Pacific War.-Biography:...
's flagship
Flagship
A flagship is a vessel used by the commanding officer of a group of naval ships, reflecting the custom of its commander, characteristically a flag officer, flying a distinguishing flag...
on 12 August. After spending the next several months working up, Hiyō arrived 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...
, together with her sister
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...
, on 9 October 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 . The A6M Zeros and D3As from the sisters 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. Nine D3As attacked, blowing the ship's stern off and destroying the barge. McFarland was not sunk, but required months of repairs. 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. A fire in the generator room occurred on 17 October and reduced her top speed to 16 knots (8.7 m/s) so Admiral Kakuta transferred his flag to Junyō while Hiyō returned to Truk for repairs. Some of her aircraft, however, were also transferred to Junyō before she left.
The remaining aircraft of her air group (16 Zeros and 17 D3As) were flown off for Rabaul 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.
Hiyō spent November in Truk, during which time she was twice slightly damaged by American air raids, before returning to Japan in early December where she was rejoined by the rest of her air group. Aside from a brief refit at Kure from 26 February to 4 March 1943, the ship was training in the Inland Sea until she sailed for Truk on 22 March. Her air group consisted of 27 Zeros and 12 D3As at this time. They were detached from Hiyō 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 carrier was again lightly damaged from bomb splinters on 12 April from an American air attack. After her air group returned, the ship arrived back in Japan on 21 May in case she was needed to relieve Japanese forces fighting on the Attu Island
Battle of Attu
The Battle of Attu, which took place from 11-30 May 1943, was fought entirely between forces of the United States and the Empire of Japan on Attu Island off the coast of Alaska. The action, which was part of the Aleutian Islands Campaign during the Pacific War, was the only land battle of World War...
.
Now the flagship of the Second Carrier Division under Rear Admiral Munetaka Sakamaki, Hiyō and her sister Junyō departed Yokosuka on 7 June en route for Truk. Later that evening, the ship was torpedoed by the submarine off Miyakejima
Miyakejima
is an island in the Izu group, southeast of Honshū, Japan, administered by the Tokyo Metropolitan government, with an area of 55.50 km². The island, 180 km south of Tokyo, is located at 34.5N and 139.34E. As of January 1, 2006, the population of the island is 2884...
. Hits in the starboard bow and boiler room knocked out all power, but she managed to return to Japan under her own power the following day. Hiyōs fighters were flown to Truk by 15 July and assigned to the light carrier . The ship was under repair at Yokosuka until 15 September. On 1 November, Hiyōs air group was reconstituted with 24 Zeros, 18 D3As and 9 B5Ns and the ship 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. On 9 December, Hiyō left Singapore en route for Truk with several deliveries on the way. The ship arrived there on 22 December and disembarked her own air group before proceeding on to Saipan
Saipan
Saipan is the largest island of the United States Commonwealth of the Northern Mariana Islands , a chain of 15 tropical islands belonging to the Marianas archipelago in the western Pacific Ocean with a total area of . The 2000 census population was 62,392...
to deliver more aircraft. The air group was transferred 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....
and later Rabaul to provide air cover for Japanese operations there.
Hiyō returned to Japan on 1 January 1944 and her air group rejoined her on 2 March, albeit without aircraft. 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. 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 ship conducted training for her 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 AdmiralVice 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 began launching their first air strike of 26 bomb-carrying A6M2 Zeros, 16 A6M5 Zeros to escort the other aircraft and seven B6Ns at about 0930. Most of these aircraft were misdirected and failed to find any American ships, although a dozen persisted in their search and found one of the American task groups. Five bomb-carrying Zeros, a B6N and an escort Zero were shot down by the defending fighters and no damage was inflicted on any American ship.
A second air strike of 27 D3As, nine D4Ys, two B6Ns and 26 escorting Zeros was launched around 1100, accompanied by at least 18 A6Ms and B6Ns from and . They had also given given an erroneous spot report and could not find any American ships. The 652nd aircraft headed for airfield at Rota
Rota (island)
Rota also known as the "peaceful island", is the southernmost island of the United States Commonwealth of the Northern Mariana Islands and the second southernmost of the Marianas Archipelago. It lies approximately 40 miles north-northeast of the United States territory of Guam...
and Guam
Guam
Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
to refuel while those from the other two carriers headed back to them. Six D4Ys and two Zeros bound for Rota spotted the carriers and en route and failed to inflict any damage on the American ships while losing five D4Ys to anti-aircraft fire. Radar had spotted those aircraft headed for Guam and they were intercepted by 41 Grumman F6F Hellcats. Only one A6M5, one D4Y and seven D3As of the 49 Japanese aircraft survived the encounter and landed.
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.