Japanese air attacks on the Mariana Islands
Encyclopedia
During World War II, a series of Japanese air attacks on the Mariana Islands took place between November 1944 and January 1945. These raids targeted United States Army Air Forces
(USAAF) bases and sought to disrupt the bombing of Japan
by B-29 Superfortress
heavy bombers operating from the islands. The Japanese lost 37 aircraft during this operation, but destroyed 11 B-29s and damaged a further 43. Preparations were also made for commando
raids on the bases in early and mid-1945 but these did not go ahead.
While the attacks on the Mariana Islands
did not seriously disrupt the USAAF air campaign, they had an effect on other American operations. After determining that the Japanese raiders were staging through Iwo Jima
, American forces stepped up their attacks on that island. While the decision to invade Iwo Jima
had been made before the raids commenced, stopping the attacks formed part of the justification for the landing. In addition, further air defense units were deployed to the Mariana Islands to protect the B-29 bases.
, Saipan
and Tinian
in the Mariana Islands
between June and August 1944 as part of the Mariana and Palau Islands campaign
. These islands were needed to provide bases for USAAF Twentieth Air Force
B-29 Superfortress heavy bombers to attack the Japanese home islands. Construction of the large air bases needed to support B-29s began on Saipan in June 1944, before the end of the Battle of Saipan
, and work on air fields on Tinian and Guam commenced in July and August respectively. The B-29s of the XXI Bomber Command
began to arrive at Saipan starting on October 12, and the 73rd Bombardment Wing
began flying warm-up missions against Japanese-held islands in the Pacific on October 27 in preparation for operations against Japan itself.
The USAAF bases in the Mariana Islands were within range of a number of Japanese air bases in the Pacific. These included Wake Island
to the east, Truk
and the Gilbert
and Marshall Islands
to the southeast, Woleai
to the south and Yap
to the southwest. To the north the Japanese had air bases in the Nampo Shoto chain of islands and Bonin Islands, which included three airstrips on Iwo Jima
. Several of the minor islands in the Mariana chain also remained in Japanese hands, and there were airfields on Rota
and Pagan. The Japanese were unable to use most of these bases, however, as they had been isolated and heavily damaged by United States air attacks, and the Imperial Japanese Army Air Force (IJAAF) and Imperial Japanese Navy
(IJN) had relatively few aircraft and pilots available.
Despite the limited threat of attack, the United States military took steps to protect the B-29 bases in the Mariana Islands. The USAAF's Seventh Air Force
played the most important role, and continuously attacked the Japanese-held islands until just before the end of the war. United States Navy
(USN) and United States Marine Corps
(USMC) aircraft and XXI Bomber Command B-29s also occasionally participated in these attacks. The Seventh Air Force also provided air defence for the Mariana Islands; this task was assigned to the 318th Fighter Group
, which was equipped with P-47 Thunderbolt fighters, and the 6th Night Fighter Squadron
which flew Northrop P-61 Black Widows. The Thunderbolts were also responsible for suppressing the Japanese-held Mariana Islands, though it proved difficult to stop the 3,600-man garrison from repairing the airfield on Pagan. In addition, the US Army stationed elements of eight anti-aircraft gun battalions and two searchlight battalions on Saipan between July 1944 and February 1945. The head of the USAAF General "Hap" Arnold
, who also directly commanded the Twentieth Air Force, was concerned about whether these defenses were sufficient, particularly given the high cost of the Superfortress bombers. Accordingly, he allocated a Microwave Early Warning
(MEW) radar to protect the bases on Saipan. This advanced radar was not immediately installed, however, as the local commanders believed that the island's air defenses were adequate.
Mitsubishi G4M
bombers (labeled
"Betty" bombers by the Allies), or Imperial Japanese Army Air Force Mitsubishi Ki-67
bombers operating from bases on mainland Japan and staging through Iwo Jima. The attacks disrupted airbase construction on several days and contributed to delays completing the B-29 base on Saipan, Isley Field
. Small numbers of Japanese soldiers who had avoided capture at the end of the battles on the islands also raided the B-29 bases on occasion, mainly in search of food.
The main Japanese air offensive against the Mariana Islands began in early November 1944. On November 1, a B-29 flying from the Marianas overflew the Tokyo
region for the first time. The next day, nine or ten IJN G4Ms belonging to the IJN Attack Hikotai 703 struck Isley Field and Kobler Field on Saipan. The raiders arrived over Saipan shortly after 1:30 am and dropped their bombs from low altitude. Only five bombs struck Isley Field, and these caused little damage. A Black Widow from the 6th Night Fighter Squadron shot down one of the G4Ms and another two were lost to other causes. On November 3 the Imperial General Headquarters
issued a statement which falsely claimed that Japanese aircraft had bombed and destroyed fifteen locations in Saipan and Tinian. A further attack by either five or ten G4Ms with fighter escorts took place at 1:30 am on November 7, but also caused little damage. The USAAF official history
states that three G4Ms were downed in this raid while another source states there were no Japanese losses. Imperial General Headquarters claimed that 20 B-29s out of 40 located were destroyed in the November 7 raid. These and all subsequent Japanese air attacks on the Marianas were overseen by the Air Training Army.
Further attacks were conducted against Saipan during late November in an attempt to disrupt the American offensive. On November 24, Marianas-based B-29s conducted their first raid against Japan, bombing targets in and around Tokyo. Three days later the Japanese mounted two raids against their bases. During the early hours of November 27, two G4Ms flying from Iwo Jima struck Isley Field from low altitude and escaped after destroying one B-29 and damaging eleven others. This attack came as a surprise to the Americans, and construction lights were still on at Isley at the start of the raid.
Later that day, twelve bomb-equipped Mitsubishi A6M "Zero" fighters from the IJN's 252 Kōkūtai
(252 Air Group) accompanied by two Nakajima C6N
"Myrt" reconnaissance aircraft for navigation purposes departed Iwo Jima for Saipan. The attackers flew at sea level to avoid US radar, and one of the A6Ms was forced to divert to Pagan after its propeller
struck a wave; this aircraft was shot down by a USAAF Thunderbolt while attempting to land. The remaining eleven A6Ms arrived over Saipan at noon, shortly after XXI Bomber Command's second raid on Tokyo had departed. These aircraft strafed
Isley Field destroying three or four B-29s and damaging up to two others. One of the Japanese pilots landed his fighter on Isley Field and fired on airfield personnel with his pistol
until he was killed by rifle
fire; this incident was witnessed by Brigadier General Haywood S. Hansell
, the commander of XXI Bomber Command. None of the ten other A6Ms survived; four were shot down by USAAF fighters and six by anti-aircraft guns. The U.S. gunners also downed a USAAF Thunderbolt in circumstances which an official assessment later described as "inexcusable". On the night of November 28/29 six or eight G4Ms from Attack Hikotai 704 bombed Isley Field from high altitude but caused little damage.
The United States military took steps to improve Saipan's defenses after the raids of November 27. Two USN destroyer
s were stationed 100 miles (160.9 km) northwest of the island to provide radar warning of further attacks. These ships detected some of the later Japanese raiders, but others managed to arrive undetected. An AN/TPS-3 radar was also flown to Saipan from Hawaii
. Arnold became frustrated that the MEW still was not in use, and on December 3 Fleet Admiral Chester W. Nimitz, the commander of the Pacific Ocean Areas, ordered that the highest priority be given to installing the radar. Despite this, it still was not ready until after the conclusion of the Japanese air campaign. Two B-24 Liberator bombers fitted with air-to-air radar sets were also dispatched to Saipan. This was the first use of airborne warning and control aircraft by the United States, but they were not used in combat.
Further attacks were mounted in December. On December 7, Japanese aircraft, which included Attack Hikotai 704 G4Ms and 110th Sentai (Wing) Ki-67s, conducted a simultaneous attack from high and low altitudes which destroyed three B-29s and damaged another 23. Japanese losses were heavy, however, with six out of eight Ki-67s of the 110th Sentai lost during this attack, the first carried out by this unit. The largest attack on Saipan occurred on the night of December 25/26 when 25 Japanese aircraft again attacked from high and low altitudes and destroyed one B-29, damaged three beyond repair and caused minor damage to a further eleven.
The raid on Christmas night was the last major Japanese attack on the Marianas. On January 2, a single Japanese aircraft destroyed one B-29 and damaged another three. A further two small raids were attempted in January and one on February 2, but none of five aircraft dispatched reached the islands and four were shot down. Overall, more than 80 Japanese aircraft were dispatched against Saipan and Tinian and these destroyed 11 B-29s, caused major damage to eight and minor damage to another 35. American casualties were 45 dead and over 200 wounded. In return, USAAF fighters and anti-aircraft guns shot down about 37 Japanese aircraft.
Nimitz ordered a major attack on Iwo Jima following the raids of November 27 and dispatched Lieutenant General Millard Harmon
, the commander of Army Air Forces in the Pacific Ocean Areas, from Hawaii to Saipan to oversee this operation. Harmon arrived there on December 5 and met with Admiral John H. Hoover
and Hansell to discuss his plans for a daylight attack using all available P-38 Lightning fighters and B-24 and B-29
bombers in conjunction with a naval bombardment
by the heavy cruiser
s , and of Cruiser Division 5. This operation was scheduled for December 7, but was delayed by a day due to bad weather. The attack began at 9:45 am on December 8 when 24 P-38s attacked the island. The B-29 raid took place at 11:00 am and the B-24s attacked at noon. Due to cloud cover over Iwo Jima the heavy bombers were forced to use radar rather than visual bombing, which limited the effectiveness of these attacks. The operation concluded with a 70-minute bombardment by the three cruisers which began at 1:47 pm. Overall, the USAAF dropped 814 tons of bombs and the cruisers fired 1,500 rounds of 8-inch and 5,334 rounds of 5-inch shells. The damage caused by this attack contributed to the cessation of Japanese raids on the Marianas until December 25.
The bombardment of Iwo Jima continued until the Battle of Iwo Jima
on February 19, 1945. The island was attacked at least once each day by the Seventh Air Force's B-24s between December 8, 1944, and February 15, 1945, and several of these aircraft were shot down. Cruiser Division 5 also conducted naval bombardments on December 24 and 27 as well as January 5 and 24. In the last of these attacks the heavy cruisers were joined by the battleship . US aircraft also mounted small-scale night attacks to disrupt Japanese repair efforts. In addition, the USAAF continued to attack the other Pacific islands within range of the Marianas until July 1945. While the attacks on Iwo Jima damaged the island's airfields, the Japanese managed to keep at least one of them operational at all times, and none were closed for more than a single day. The need to repair damage to the airfields forced the Japanese garrison on Iwo Jima to divert labor from building defensive positions, however. The combination of heavy losses over Saipan and damage to the airfields on Iwo Jima caused the Japanese to break off their attacks against the Marianas on 2 January. Few Japanese aircraft visited Iwo Jima starting in January, and due to their losses in the Philippines Campaign, the IJAAF and IJN lacked the long-ranged aircraft needed to resume attacks on the Marianas in early 1945.
formation, was ordered to attack the B-29 bases at Saipan. A 136-man force designated the Giretsu Airborne Unit was formed for this suicide mission, which called for the destruction with explosive charges of B-29s by troops carried by Mitsubishi Ki-21
"Sally" bombers. These aircraft lacked the range to reach Saipan directly from Japan, and it was planned that they would refuel at Iwo Jima. The commandos undertook intensive training at Saitama Kanto and the raid was scheduled to take place on January 17, 1945, but was canceled after damage to the airfields at Iwo Jima. The Giretsu Airborne Unit instead attacked a U.S. airbase at Okinawa on 24 May, destroying nine aircraft and damaging another 29.
Following the perceived success of the raid on Okinawa the IJN developed plans for a force of naval commandos to attack airfields in the Marianas. On June 24, it issued orders for a raid involving 30 Yokosuka P1Y
"Frances" bombers and 20 G4Ms carrying naval commandos. The plan, Operation Tsurugi, called for the P1Ys to strafe the airfields before the G4Ms crash-landed on them. The commandos would then destroy as many B-29s as possible before fighting to the death. The commandos and G4Ms selected to land in the Marianas conducted intensive training at bases in northern Honshu
and the operation was scheduled for late July. USN carrier raids on this area on July 14 and 15 destroyed many of the force's aircraft, however, and the operation was postponed until August.
Following its postponement the scale of Operation Tsurugi was expanded to include 60 G4Ms carrying 300 naval commandos from the 101st Kure Special Naval Landing Force
and 300 Army commandos from the 1st Raiding Regiment. It was planned that 20 G4Ms would carry naval commandos to Guam, another 20 would carry army commandos to Saipan and the remaining 20 would transport a joint Army–Navy force to Tinian. The revised plan also called for a B-29 to be captured and flown back to Japan. This attack was scheduled to take place between August 19 and 23. Allied intelligence became aware of Operation Tsurugi, however, and another carrier attack on Honshu destroyed 29 G4Ms and 20 P1Ys on August 9. While the operation was not called off after this raid, it did not go ahead after the Japanese surrender on 15 August.
When the U.S. military was considering future operations in the Bonin Islands during August 1944 the planners assessed that an occupation of Iwo Jima might be necessary to protect the Marianas from attack, and after the war this was given as one of the justifications for the costly invasion of the island. However, this was not necessary due to the success of the Seventh Air Force and the USN's campaign against Iwo Jima's airfields as well as the Japanese military's shortage of long-ranged aircraft. In any event, the decision to invade Iwo Jima was made a month before the major attacks on the B-29 bases began, and there were no raids on the Marianas in the seven weeks before the landings began on February 19.
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....
(USAAF) bases and sought to disrupt the bombing of Japan
Air raids on Japan
During World War II the Allied forces conducted many air raids on Japan which caused extensive destruction to the country's cities and killed over 300,000 people. These attacks began with the Doolittle Raid in mid-April 1942, but did not resume until June 1944 when United States Army Air Forces ...
by B-29 Superfortress
B-29 Superfortress
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II...
heavy bombers operating from the islands. The Japanese lost 37 aircraft during this operation, but destroyed 11 B-29s and damaged a further 43. Preparations were also made for commando
Commando
In English, the term commando means a specific kind of individual soldier or military unit. In contemporary usage, commando usually means elite light infantry and/or special operations forces units, specializing in amphibious landings, parachuting, rappelling and similar techniques, to conduct and...
raids on the bases in early and mid-1945 but these did not go ahead.
While the attacks 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...
did not seriously disrupt the USAAF air campaign, they had an effect on other American operations. After determining that the Japanese raiders were staging through Iwo Jima
Iwo Jima
Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...
, American forces stepped up their attacks on that island. While the decision to invade Iwo Jima
Battle of Iwo Jima
The Battle of Iwo Jima , or Operation Detachment, was a major battle in which the United States fought for and captured the island of Iwo Jima from the Empire of Japan. The U.S...
had been made before the raids commenced, stopping the attacks formed part of the justification for the landing. In addition, further air defense units were deployed to the Mariana Islands to protect the B-29 bases.
Background
United States forces captured GuamGuam
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...
, 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...
and Tinian
Tinian
Tinian is one of the three principal islands of the Commonwealth of the Northern Mariana Islands.-Geography:Tinian is about 5 miles southwest of its sister island, Saipan, from which it is separated by the Saipan Channel. It has a land area of 39 sq.mi....
in 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...
between June and August 1944 as part of the Mariana and Palau Islands campaign
Mariana and Palau Islands campaign
The Mariana and Palau Islands campaign, also known as Operation Forager, was an offensive launched by United States forces against Imperial Japanese forces in the Mariana Islands and Palau in the Pacific Ocean between June and November, 1944 during the Pacific War...
. These islands were needed to provide bases for USAAF Twentieth Air Force
Twentieth Air Force
The Twentieth Air Force is a numbered air force of the United States Air Force Global Strike Command . It is headquartered at F.E. Warren Air Force Base, Wyoming.20 AF's primary mission is Intercontinental Ballistic Missile operations...
B-29 Superfortress heavy bombers to attack the Japanese home islands. Construction of the large air bases needed to support B-29s began on Saipan in June 1944, before the end of the Battle of Saipan
Battle of Saipan
The Battle of Saipan was a battle of the Pacific campaign of World War II, fought on the island of Saipan in the Mariana Islands from 15 June-9 July 1944. The Allied invasion fleet embarking the expeditionary forces left Pearl Harbor on 5 June 1944, the day before Operation Overlord in Europe was...
, and work on air fields on Tinian and Guam commenced in July and August respectively. The B-29s of the XXI Bomber Command
XXI Bomber Command
The XXI Bomber Command was a unit of the Twentieth Air Force in Guam for strategic bombing during World War II.- Lineage:* Constituted as XXI Bomber Command on 1 Mar 1944, and activated the same day.-Assignments:...
began to arrive at Saipan starting on October 12, and the 73rd Bombardment Wing
73d Air Division
The 73d Air Division is an inactive United States Air Force unit. Its last assignment was with Air Defense Command, based at Tyndall Air Force Base, Florida. It was inactivated on 1 April 1966.-World War II:...
began flying warm-up missions against Japanese-held islands in the Pacific on October 27 in preparation for operations against Japan itself.
The USAAF bases in the Mariana Islands were within range of a number of Japanese air bases in the Pacific. These included Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
to the east, 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...
and the Gilbert
Gilbert Islands
The Gilbert Islands are a chain of sixteen atolls and coral islands in the Pacific Ocean. They are the main part of Republic of Kiribati and include Tarawa, the site of the country's capital and residence of almost half of the population.-Geography:The atolls and islands of the Gilbert Islands...
and Marshall Islands
Marshall Islands
The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...
to the southeast, Woleai
Woleai
Woleai is a coral atoll of twenty-two islands in the eastern Caroline Islands in the Pacific Ocean, and forms a legislative district in Yap State in the Federated States of Micronesia and is located approximately west-northwest of Ifalik and northeast of Eauripik...
to the south and Yap
Yap
Yap, also known as Wa'ab by locals, is an island in the Caroline Islands of the western Pacific Ocean. It is a state of the Federated States of Micronesia. Yap's indigenous cultures and traditions are still strong compared to other neighboring islands. The island of Yap actually consists of four...
to the southwest. To the north the Japanese had air bases in the Nampo Shoto chain of islands and Bonin Islands, which included three airstrips on Iwo Jima
Iwo Jima
Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...
. Several of the minor islands in the Mariana chain also remained in Japanese hands, and there were airfields on 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 Pagan. The Japanese were unable to use most of these bases, however, as they had been isolated and heavily damaged by United States air attacks, and the Imperial Japanese Army Air Force (IJAAF) and 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...
(IJN) had relatively few aircraft and pilots available.
Despite the limited threat of attack, the United States military took steps to protect the B-29 bases in the Mariana Islands. The USAAF's Seventh Air Force
Seventh Air Force
The Seventh Air Force is a numbered air force of the United States Air Force Pacific Air Forces . It is headquartered at Osan Air Base, Republic of Korea....
played the most important role, and continuously attacked the Japanese-held islands until just before the end of the war. United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
(USN) and United States Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
(USMC) aircraft and XXI Bomber Command B-29s also occasionally participated in these attacks. The Seventh Air Force also provided air defence for the Mariana Islands; this task was assigned to the 318th Fighter Group
318th Fighter Group
The 318th Fighter Group was a World War II United States Army Air Forces combat organization. It served primarily in the Pacific Ocean theater of World War II.-History:...
, which was equipped with P-47 Thunderbolt fighters, and the 6th Night Fighter Squadron
6th Night Fighter Squadron
The 6th Night Fighter Squadron is an inactive United States Air Force unit. Its last assignment was with Seventh Air Force, being inactivated at Wheeler Field, Hawaii on February 20, 1947....
which flew Northrop P-61 Black Widows. The Thunderbolts were also responsible for suppressing the Japanese-held Mariana Islands, though it proved difficult to stop the 3,600-man garrison from repairing the airfield on Pagan. In addition, the US Army stationed elements of eight anti-aircraft gun battalions and two searchlight battalions on Saipan between July 1944 and February 1945. The head of the USAAF General "Hap" Arnold
Henry H. Arnold
Henry Harley "Hap" Arnold was an American general officer holding the grades of General of the Army and later General of the Air Force. Arnold was an aviation pioneer, Chief of the Air Corps , Commanding General of the U.S...
, who also directly commanded the Twentieth Air Force, was concerned about whether these defenses were sufficient, particularly given the high cost of the Superfortress bombers. Accordingly, he allocated a Microwave Early Warning
Early warning radar
An early warning radar is any radar system used primarily for the long-range detection of its targets, i.e., allowing defences to be alerted as early as possible before the intruder reaches its target, giving the defences the maximum time in which to operate...
(MEW) radar to protect the bases on Saipan. This advanced radar was not immediately installed, however, as the local commanders believed that the island's air defenses were adequate.
Japanese attacks
The first Japanese air attacks on the B-29 bases occurred while they were under construction. Between June 24 and July 21 the 6th Night Fighter Squadron attempted to intercept 37 raids on Saipan, and claimed three "kills". These raids typically comprised twelve Japanese NavyImperial Japanese Navy Air Service
The Imperial Japanese Navy Air Service was the air arm of the Imperial Japanese Navy during World War II, the organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War.It was controlled by the Navy Staff of the Imperial Japanese Navy and...
Mitsubishi G4M
Mitsubishi G4M
The Mitsubishi G4M 一式陸上攻撃機, 一式陸攻 Isshiki rikujō kōgeki ki, Isshikirikkō was the main twin-engine, land-based bomber used by the Imperial Japanese Navy Air Service in World War II. The Allies gave the G4M the reporting name Betty...
bombers (labeled
World War II Allied names for Japanese aircraft
The World War II Allied names for Japanese aircraft were reporting names, often described as codenames, given by Allied personnel to Imperial Japanese aircraft during the Pacific campaign of World War II. The names were used by Allied personnel to identify Japanese aircraft for reporting and...
"Betty" bombers by the Allies), or Imperial Japanese Army Air Force Mitsubishi Ki-67
Mitsubishi Ki-67
The Mitsubishi Ki-67 Hiryū was a twin-engine medium bomber produced by Mitsubishi and used by the Imperial Japanese Army Air Force in World War II. Its Army designation was "Type 4 Heavy Bomber" .-Design:The Ki-67 was the result of a 1941 Japanese army specification for a successor to the Nakajima...
bombers operating from bases on mainland Japan and staging through Iwo Jima. The attacks disrupted airbase construction on several days and contributed to delays completing the B-29 base on Saipan, Isley Field
Saipan International Airport
- See also :* East Field * USAAF in the Central Pacific-References:* Dorr, Robert F. B-29 Units of World War II. Botley, Oxford, UK: Osprey Publishing, 2002. ISBN 1-84176-285-7...
. Small numbers of Japanese soldiers who had avoided capture at the end of the battles on the islands also raided the B-29 bases on occasion, mainly in search of food.
The main Japanese air offensive against the Mariana Islands began in early November 1944. On November 1, a B-29 flying from the Marianas overflew the Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
region for the first time. The next day, nine or ten IJN G4Ms belonging to the IJN Attack Hikotai 703 struck Isley Field and Kobler Field on Saipan. The raiders arrived over Saipan shortly after 1:30 am and dropped their bombs from low altitude. Only five bombs struck Isley Field, and these caused little damage. A Black Widow from the 6th Night Fighter Squadron shot down one of the G4Ms and another two were lost to other causes. On November 3 the Imperial General Headquarters
Imperial General Headquarters
The as part of the Supreme War Council was established in 1893 to coordinate efforts between the Imperial Japanese Army and Imperial Japanese Navy during wartime...
issued a statement which falsely claimed that Japanese aircraft had bombed and destroyed fifteen locations in Saipan and Tinian. A further attack by either five or ten G4Ms with fighter escorts took place at 1:30 am on November 7, but also caused little damage. The USAAF official history
Official history
An official history is a work of history which is sponsored, authorised, or endorsed by its subject. The term is most commonly used for histories which are produced at a government's behest....
states that three G4Ms were downed in this raid while another source states there were no Japanese losses. Imperial General Headquarters claimed that 20 B-29s out of 40 located were destroyed in the November 7 raid. These and all subsequent Japanese air attacks on the Marianas were overseen by the Air Training Army.
Further attacks were conducted against Saipan during late November in an attempt to disrupt the American offensive. On November 24, Marianas-based B-29s conducted their first raid against Japan, bombing targets in and around Tokyo. Three days later the Japanese mounted two raids against their bases. During the early hours of November 27, two G4Ms flying from Iwo Jima struck Isley Field from low altitude and escaped after destroying one B-29 and damaging eleven others. This attack came as a surprise to the Americans, and construction lights were still on at Isley at the start of the raid.
Later that day, twelve bomb-equipped Mitsubishi A6M "Zero" fighters from the IJN's 252 Kōkūtai
252 Air Group
was a fighter aircraft unit of the Imperial Japanese Navy during the Pacific campaign of World War II. The unit's name is translated into English as the "252 Air Group" instead of "252nd Air Group" because each numeral in the unit's name was a discrete identifier of information pertaining to the...
(252 Air Group) accompanied by two Nakajima C6N
Nakajima C6N
-See also:-References:NotesBibliography* Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 1970. ISBN 0-370-00033-1 ....
"Myrt" reconnaissance aircraft for navigation purposes departed Iwo Jima for Saipan. The attackers flew at sea level to avoid US radar, and one of the A6Ms was forced to divert to Pagan after its propeller
Propeller (aircraft)
Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...
struck a wave; this aircraft was shot down by a USAAF Thunderbolt while attempting to land. The remaining eleven A6Ms arrived over Saipan at noon, shortly after XXI Bomber Command's second raid on Tokyo had departed. These aircraft strafed
Strafing
Strafing is the practice of attacking ground targets from low-flying aircraft using aircraft-mounted automatic weapons. This means, that although ground attack using automatic weapons fire is very often accompanied with bombing or rocket fire, the term "strafing" does not specifically include the...
Isley Field destroying three or four B-29s and damaging up to two others. One of the Japanese pilots landed his fighter on Isley Field and fired on airfield personnel with his pistol
Pistol
When distinguished as a subset of handguns, a pistol is a handgun with a chamber that is integral with the barrel, as opposed to a revolver, wherein the chamber is separate from the barrel as a revolving cylinder. Typically, pistols have an effective range of about 100 feet.-History:The pistol...
until he was killed by rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
fire; this incident was witnessed by Brigadier General Haywood S. Hansell
Haywood S. Hansell
Haywood Shepherd Hansell Jr., was a general officer in the United States Army Air Forces during World War II, and later the United States Air Force...
, the commander of XXI Bomber Command. None of the ten other A6Ms survived; four were shot down by USAAF fighters and six by anti-aircraft guns. The U.S. gunners also downed a USAAF Thunderbolt in circumstances which an official assessment later described as "inexcusable". On the night of November 28/29 six or eight G4Ms from Attack Hikotai 704 bombed Isley Field from high altitude but caused little damage.
The United States military took steps to improve Saipan's defenses after the raids of November 27. Two USN 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 were stationed 100 miles (160.9 km) northwest of the island to provide radar warning of further attacks. These ships detected some of the later Japanese raiders, but others managed to arrive undetected. An AN/TPS-3 radar was also flown to Saipan from Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. Arnold became frustrated that the MEW still was not in use, and on December 3 Fleet Admiral Chester W. Nimitz, the commander of the Pacific Ocean Areas, ordered that the highest priority be given to installing the radar. Despite this, it still was not ready until after the conclusion of the Japanese air campaign. Two B-24 Liberator bombers fitted with air-to-air radar sets were also dispatched to Saipan. This was the first use of airborne warning and control aircraft by the United States, but they were not used in combat.
Further attacks were mounted in December. On December 7, Japanese aircraft, which included Attack Hikotai 704 G4Ms and 110th Sentai (Wing) Ki-67s, conducted a simultaneous attack from high and low altitudes which destroyed three B-29s and damaged another 23. Japanese losses were heavy, however, with six out of eight Ki-67s of the 110th Sentai lost during this attack, the first carried out by this unit. The largest attack on Saipan occurred on the night of December 25/26 when 25 Japanese aircraft again attacked from high and low altitudes and destroyed one B-29, damaged three beyond repair and caused minor damage to a further eleven.
The raid on Christmas night was the last major Japanese attack on the Marianas. On January 2, a single Japanese aircraft destroyed one B-29 and damaged another three. A further two small raids were attempted in January and one on February 2, but none of five aircraft dispatched reached the islands and four were shot down. Overall, more than 80 Japanese aircraft were dispatched against Saipan and Tinian and these destroyed 11 B-29s, caused major damage to eight and minor damage to another 35. American casualties were 45 dead and over 200 wounded. In return, USAAF fighters and anti-aircraft guns shot down about 37 Japanese aircraft.
U.S. counterattacks
After the Marianas began to come under attack, the United States military stepped up its raids on the Japanese islands within range of the B-29 bases. Particular attention was given to Iwo Jima, as it was correctly assumed that the Japanese aircraft which attacked the Marianas were flying from Japan and staging through the island enroute to their targets. Following the first raid against Saipan in November, XXI Bomber Command B-29s were dispatched against Iwo Jima's airfields on November 5 and 8. These attacks were primarily training missions and caused little damage. The first raid was unopposed by the Japanese, but the second was met by eight fighters which inflicted light damage on a B-29; this was the first combat damage suffered by any of XXI Bomber Command's aircraft. The Seventh Air Force also increased the number of B-24 Liberator attacks on Iwo Jima, and these attacked the island 30 times during November.Nimitz ordered a major attack on Iwo Jima following the raids of November 27 and dispatched Lieutenant General Millard Harmon
Millard Harmon
Millard Fillmore Harmon Jr. was a Lieutenant General in the United States Army Air Forces during the Pacific campaign in World War II....
, the commander of Army Air Forces in the Pacific Ocean Areas, from Hawaii to Saipan to oversee this operation. Harmon arrived there on December 5 and met with Admiral John H. Hoover
John H. Hoover
Admiral John Howard Hoover held several flag commands during World War II most notably those in the Central Pacific under Chester W. Nimitz...
and Hansell to discuss his plans for a daylight attack using all available P-38 Lightning fighters and B-24 and B-29
bombers in conjunction with a naval bombardment
Naval gunfire support
Naval gunfire support is the use of naval artillery to provide fire support for amphibious assault and other troops operating within their range. NGFS is one of a number of disciplines encompassed by the term Naval Fires...
by the heavy cruiser
Heavy cruiser
The heavy cruiser was a type of cruiser, a naval warship designed for long range, high speed and an armament of naval guns roughly 203mm calibre . The heavy cruiser can be seen as a lineage of ship design from 1915 until 1945, although the term 'heavy cruiser' only came into formal use in 1930...
s , and of Cruiser Division 5. This operation was scheduled for December 7, but was delayed by a day due to bad weather. The attack began at 9:45 am on December 8 when 24 P-38s attacked the island. The B-29 raid took place at 11:00 am and the B-24s attacked at noon. Due to cloud cover over Iwo Jima the heavy bombers were forced to use radar rather than visual bombing, which limited the effectiveness of these attacks. The operation concluded with a 70-minute bombardment by the three cruisers which began at 1:47 pm. Overall, the USAAF dropped 814 tons of bombs and the cruisers fired 1,500 rounds of 8-inch and 5,334 rounds of 5-inch shells. The damage caused by this attack contributed to the cessation of Japanese raids on the Marianas until December 25.
The bombardment of Iwo Jima continued until the Battle of Iwo Jima
Battle of Iwo Jima
The Battle of Iwo Jima , or Operation Detachment, was a major battle in which the United States fought for and captured the island of Iwo Jima from the Empire of Japan. The U.S...
on February 19, 1945. The island was attacked at least once each day by the Seventh Air Force's B-24s between December 8, 1944, and February 15, 1945, and several of these aircraft were shot down. Cruiser Division 5 also conducted naval bombardments on December 24 and 27 as well as January 5 and 24. In the last of these attacks the heavy cruisers were joined by the battleship . US aircraft also mounted small-scale night attacks to disrupt Japanese repair efforts. In addition, the USAAF continued to attack the other Pacific islands within range of the Marianas until July 1945. While the attacks on Iwo Jima damaged the island's airfields, the Japanese managed to keep at least one of them operational at all times, and none were closed for more than a single day. The need to repair damage to the airfields forced the Japanese garrison on Iwo Jima to divert labor from building defensive positions, however. The combination of heavy losses over Saipan and damage to the airfields on Iwo Jima caused the Japanese to break off their attacks against the Marianas on 2 January. Few Japanese aircraft visited Iwo Jima starting in January, and due to their losses in the Philippines Campaign, the IJAAF and IJN lacked the long-ranged aircraft needed to resume attacks on the Marianas in early 1945.
Operation Tsurugi
In December 1944, the Japanese Army's 1st Raiding Regiment, an elite commandoCommando
In English, the term commando means a specific kind of individual soldier or military unit. In contemporary usage, commando usually means elite light infantry and/or special operations forces units, specializing in amphibious landings, parachuting, rappelling and similar techniques, to conduct and...
formation, was ordered to attack the B-29 bases at Saipan. A 136-man force designated the Giretsu Airborne Unit was formed for this suicide mission, which called for the destruction with explosive charges of B-29s by troops carried by Mitsubishi Ki-21
Mitsubishi Ki-21
The was a Japanese bomber during World War II. It began operations during the Second Sino-Japanese War participating in the Nomonhan Incident, and in the first stages of the Pacific War, including the Malayan, Burmese, Dutch East Indies and New Guinea Campaigns...
"Sally" bombers. These aircraft lacked the range to reach Saipan directly from Japan, and it was planned that they would refuel at Iwo Jima. The commandos undertook intensive training at Saitama Kanto and the raid was scheduled to take place on January 17, 1945, but was canceled after damage to the airfields at Iwo Jima. The Giretsu Airborne Unit instead attacked a U.S. airbase at Okinawa on 24 May, destroying nine aircraft and damaging another 29.
Following the perceived success of the raid on Okinawa the IJN developed plans for a force of naval commandos to attack airfields in the Marianas. On June 24, it issued orders for a raid involving 30 Yokosuka P1Y
Yokosuka P1Y
|-See also:-References:NotesBibliography* Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam 7 Company Ltd., 1970. ISBN 0-370-00033-1 ....
"Frances" bombers and 20 G4Ms carrying naval commandos. The plan, Operation Tsurugi, called for the P1Ys to strafe the airfields before the G4Ms crash-landed on them. The commandos would then destroy as many B-29s as possible before fighting to the death. The commandos and G4Ms selected to land in the Marianas conducted intensive training at bases in northern Honshu
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
and the operation was scheduled for late July. USN carrier raids on this area on July 14 and 15 destroyed many of the force's aircraft, however, and the operation was postponed until August.
Following its postponement the scale of Operation Tsurugi was expanded to include 60 G4Ms carrying 300 naval commandos from the 101st Kure Special Naval Landing Force
Japanese Special Naval Landing Forces
The Japanese Special Naval Landing Forces , were the marine troops of the Imperial Japanese Navy and were a part of the IJN Land Forces...
and 300 Army commandos from the 1st Raiding Regiment. It was planned that 20 G4Ms would carry naval commandos to Guam, another 20 would carry army commandos to Saipan and the remaining 20 would transport a joint Army–Navy force to Tinian. The revised plan also called for a B-29 to be captured and flown back to Japan. This attack was scheduled to take place between August 19 and 23. Allied intelligence became aware of Operation Tsurugi, however, and another carrier attack on Honshu destroyed 29 G4Ms and 20 P1Ys on August 9. While the operation was not called off after this raid, it did not go ahead after the Japanese surrender on 15 August.
Aftermath
The Japanese attacks on the Mariana Islands during 1944 and 1945 did not seriously disrupt the USAAF's strategic air campaign against Japan. They did, however, force the United States to allocate forces to defend the islands in order to prevent further losses of expensive B-29s. Moreover, due to the high cost of the heavy bombers, the ratio of losses was in favor of the Japanese.When the U.S. military was considering future operations in the Bonin Islands during August 1944 the planners assessed that an occupation of Iwo Jima might be necessary to protect the Marianas from attack, and after the war this was given as one of the justifications for the costly invasion of the island. However, this was not necessary due to the success of the Seventh Air Force and the USN's campaign against Iwo Jima's airfields as well as the Japanese military's shortage of long-ranged aircraft. In any event, the decision to invade Iwo Jima was made a month before the major attacks on the B-29 bases began, and there were no raids on the Marianas in the seven weeks before the landings began on February 19.