1st Air Fleet (Imperial Japanese Navy)

1st Air Fleet (IJNAS) 第一航空艦隊 (Dai-ichi Kōkū Kantai)
Rising Sun Flag
Active	10 April 1941 – 14 July 1942 1 June 1943 – 15 June 1945
Country	Empire of Japan
Allegiance	Empire of Japan
Branch	Imperial Japanese Navy
Type	Naval Air Fleet ('Kantai')
Engagements	Pearl Harbor Indian Ocean Coral Sea Midway Santa Cruz Philippine Sea Leyte Gulf
Insignia
Roundel

The 1st Air Fleet (第一航空艦隊, Daiichi Kōkū Kantai) also known as the Kidō Butai ("Mobile Force"), was a name used for a combined carrier battle group comprising most of the aircraft carriers and carrier air groups of the Imperial Japanese Navy (IJN), during the Pacific War.

At the time of its best-known operation, the attack on Pearl Harbor, in December 1941, the 1st Air Fleet was the world's largest fleet of aircraft carriers.

Origins

Japanese seaplane carrier Wakamiya.

In 1912, the British Royal Navy had established its own flying branch, the Royal Naval Air Service (RNAS). The IJN was modeled on the Royal Navy and the IJN Admiralty sought establishment of their own Naval Air Service. The IJN had also observed technical developments in other countries and saw military potential of the airplane. In 1913, the IJN seaplane carrier Wakamiya was converted into a seaplane tender and aircraft were purchased. The 1st and 2nd Air Fleet were to be the primary attack force of the IJNAS.

Organization

The Imperial Japanese Navy Air Service's carrier-based Air Corps or Naval Air Group (Kōkūtai) was a major component of the Combined Fleet (Rengō Kantai), and whose size (from a handful to 80 or 90 aircraft) was dependent on the mission and type of aircraft carrier used.^[1] Several Kōkūtai formed a Koku Sentai (Naval Air Flotilla or Carrier Division), while a Naval Air Fleet (Kantai) was made up of several Koku Sentai.^[2]

As Carrier Task Force

On 10 April 1941 the Imperial Japanese Navy formed the First Air Fleet (Dai-ichi KōKū Kantai) consisting of all seven of Japan's aircraft fleet carriers and light carriers with a total of 474 aircraft. This was a naval battlegroup at the time with the single most powerful concentration of naval aviation in the world.^[3]

The large fleet carriers had three types of aircraft; fighters, level/torpedo bombers, and dive bombers. The smaller carriers tended to have only two types of aircraft, fighters and torpedo bombers. The carrier-based Kōkūtai numbered over 1500 pilots with over 1500 aircraft. At the beginning of the Pacific War, there would be 6 fleet carriers—Akagi, Kaga, Soryu, Hiryu, Shokaku, and Zuikaku—and two light carriers, Ryujo and Zuiho.

Kidō Butai

The Kidō Butai (機動部隊, "Mobile Unit/Force") was the Combined Fleet's tactical designation for its combined carrier battle groups.^[4] The title was used as a term of convenience; it was not a formal name for the organization. It consisted of Japan's six largest carriers, carrying the 1st Air Fleet. This mobile task force was created for executing the attack on Pearl Harbor under Admiral Chūichi Nagumo in 1941.^[5] For the attack on Pearl Harbor, the Kidō Butai consisted of six aircraft carriers (commanded by Chuichi Nagumo, Tamon Yamaguchi and Chūichi Hara) with 414 airplanes, two battleships, three cruisers, nine destroyers, eight tankers, 23 submarines, and four midget submarines. However, these escort ships were borrowed from other fleet and squadrons. It was considered the single most powerful naval fleet until four of the six aircraft carriers of the unit were destroyed in the disastrous Battle of Midway. On 14 July 1942, all carriers were moved to the 3rd Fleet.

Carriers of the Kidō Butai, 1941
1st Carrier Division
Akagi
Kaga
2nd Carrier Division
Sōryū
Hiryū
3rd Carrier Division
Zuihō
Hōshō
4th Carrier Division
Ryūjō
Taiyō
5th Carrier Division
Shōkaku
Zuikaku

Transition (extract)

Commanders

• Commander in Chief

• Chief of Staff

As land-based Air Fleet

On 1 June 1943, the 1st Air Fleet was reborn as the land-based Air Fleet. On 30 September 1943, a cabinet meeting planned the Absolute National Defence Zone (絶対国防圏, Zettai Kokubōken) strategy.^[6] The plan intended the Kuril Islands, Bonin Islands, Mariana Islands, Caroline Islands, Geelvink Bay (Biak), Sunda Islands and Burma to be unsinkable aircraft carriers. The 1st Air Fleet became the main force of this plan. However, it was soundly beaten in the Battle of Philippine Sea. The IJN then moved the air fleet to the Philippines to regroup. However, the IJN lost the air fleet, as it was not combat ready in the Aerial Battle of Taiwan–Okinawa. After the battle it had only 30 aircraft. The only tactic left for them was the kamikaze attack.

Transition (extract)

Commanders

• Commander in chief

• Chief of Staff

• 
  Admiral Chūichi Nagumo (Commander-in-Chief, 1st Carrier Division)
• 
  Vice Admiral Tamon Yamaguchi (2nd Carrier Division)
• 
  Vice Admiral Kakuji Kakuta (4th Carrier Division - from 1941)
• 
  Vice Admiral Chūichi Hara (5th Carrier Division)
• 
  Vice Admiral Gunichi Mikawa (3rd Battleship Division)
• 
  Vice Admiral Sentarō Ōmori (1st Destroyer Squadron)
• 
  Vice Admiral Shigeyoshi Miwa (3rd Submarine Squadron)
• 
  Vice Admiral Ryūnosuke Kusaka (Chief of staff, 1st Air Fleet)
• 
  Rear Admiral Tomeo Kaku (2nd Carrier Division: Hiryu)
• 
  Rear Admiral Ryusaku Yanagimoto (2nd Carrier Division: Soryu)

Operations

Planes taking off

1st Air Fleet Aichi dive bombers preparing to bomb American naval base in Pearl Harbor, Hawaii

Carrier Shōkaku preparing to launch the attack on Pearl Harbor.

Japanese aircraft carrier Shōhō being hit by bombs and torpedoes at the Battle of the Coral Sea.

Japanese aircraft at the Battle of the Santa Cruz Islands.

Zuikaku sinking after being hit at the Battle of Leyte Gulf.

Pearl Harbor

The Kidō Butai (also known as the Carrier Striking Task Force) set sail from Hittokapu Bay, Japan under Vice Admiral Chūichi Nagumo on 26 November 1941, arriving in Hawaiian waters on Sunday December 7, 1941 Hawaiian time. At around 8am, the first wave began its attack on the US Pacific Fleet based at Pearl Harbor and on outlying airfields. By the end of the day 21 American ships were either sunk or crippled, 188 aircraft were destroyed, and over 3,500 American personnel were casualties of war. Japan was now formally at war with the United States.

For the attack on Pearl Harbor, this fleet had a strength of 103 level bombers, 128 dive bombers, 40 torpedo bombers, 88 fighter planes, and plus 91 planes with a total of 441 planes.

Bombing of Darwin

The Bombing of Darwin, also known as the Battle of Darwin,^[7] on 19 February 1942 was the largest single attack ever mounted by a foreign power on Australia. On that day, 242 Japanese aircraft, in two separate raids, attacked the town, ships in Darwin's harbour and the town's two airfields in an attempt to prevent the Allies from using them as bases to contest the invasion of Timor and Java The town was only lightly defended and the Japanese inflicted heavy losses upon the Allied forces at little cost to themselves. The urban areas of Darwin also suffered some damage from the raids and there were a number of civilian casualties.

Indian Ocean Raid

Between 31 March and 10 April 1942 the Japanese conducted a naval sortie against Allied naval forces in the Indian Ocean. The Fast Carrier Task Force (Kidō Butai), consisting of six carriers commanded by Admiral Chūichi Nagumo, inflicted heavy losses on the British fleet, with the sinking of 1 carrier, 2 cruisers, 2 destroyers, and 23 merchant ships for the loss of 20 aircraft. Attacks on the island of Ceylon were also carried out.

Battle of the Coral Sea

The 1st Air Fleet dispatched the Fifth Carrier Division in the Coral Sea during the return from the Indian Ocean. On May 7 the USN sighted the Port Moresby invasion force and mistook it for the main carrier force. Admiral Fletcher sent an aircraft strike which sank the IJN light carrier Shōhō. After this loss of air cover, the Port Moresby invasion force abandoned its mission and retreated north. On the same day the IJN sighted and sank USN destroyer Sims and oiler Neosho. The primary action took place on 8 May. Both carrier forces sighted and attacked each other. As a result, Lexington was sunk and Yorktown was damaged by a Japanese air strike. USN aircraft managed to damage Shōkaku, meaning that she and her sister ship were unable to participate in the following operation. The remaining fleet returned to Japan to prepare for the Midway invasion (Operation MI).

Battle of Midway

Admiral Isoroku Yamamoto planned to lure and destroy USN carriers by attacking the Midway Islands in June 1942. The Japanese were unaware that the United States had broken their naval code. As a result of this, USN carriers were already in the area when the Japanese attacked Midway. On 3 June US land-based bombers from Midway attacked the Japanese fleet but scored no hits. On 4 June, due to the poor reconnaissance efforts and tactical mistakes of Vice Admiral Chūichi Nagumo, USN dive bombers were able to surprise the Japanese carrier force and destroyed three carriers (Akagi, Kaga and Sōryū). At the time of the attack the Japanese carriers were in the process of preparing to launch an air strike against the US carriers and their hangars were full of loaded aircraft, bombs and aviation fuel which decisively contributed to their destruction. Carrier Hiryū managed to survive the attack and Rear Admiral Tamon Yamaguchi launched a strike against Yorktown. Aircraft from Hiryū managed to cripple Yorktown, which was later sunk by a Japanese submarine I-168. In response, US launched a strike against Hiryū and sunk her. That day the Japanese lost four aircraft carriers and much of their experienced aircrew.

Battle of the Eastern Solomons

The battle took place in August 1942. It was one of the two battles around the Solomon Islands where the IJN carrier force engaged USN carrier force. As a response to Allied landings on Guadalcanal in early August, the Japanese planned a counterattack for late August. On 24 August the IJN carrier force (Shōkaku, Zuikaku and Ryūjō) under the command of Vice Admiral Chūichi Nagumo arrived in the Solomons area. Ryūjō was then separated and sent to attack Henderson Field. She was spotted by US reconnaissance aircraft that morning. Admiral Fletcher sent a strike force in the afternoon which sunk her. About the same time the Japanese sighted the US carrier force (Enterprise and Saratoga) and launched an air strike which badly damaged Enterprise.

Battle of Santa Cruz Islands

This was the second carrier battle of the Guadalcanal Campaign. The Japanese Army planned a major ground offensive on Guadalcanal for the end of October 1942. The Japanese Navy was to support this offensive. The IJN force consisted of four carriers (Shōkaku, Zuikaku, Jun'yō and light carrier Zuihō). The USN had two carriers available at the time (Enterprise and Hornet). The two forces first sighted each other in the morning of 26 October. In the following air strikes, the USN managed to heavily damage Shōkaku and Zuihō. In exchange, the IJN sank carrier Hornet and badly damaged Enterprise. Despite the tactical victory of the Japanese at the Battle of Santa Cruz Islands, their experienced aircrew was almost entirely wiped out in the two carrier battles around the Solomon Islands and they were no longer able to conduct carrier operations for some time.

Battle of the Philippine Sea

The Invasion of Mariana Islands in June 1944 came as a surprise to the Japanese who had expected the next US target to be either the Palau Islands or the Caroline Islands. In response, the IJN moved to counterattack the US forces. Vice Admiral Jisaburō Ozawa had five large carriers (Taihō, Shōkaku, Zuikaku, Jun'yō and Hiyō) and an additional four light carriers under his command. By this time, the IJN was able to train new aircrew for their carriers to replace those lost during the battles in 1942, but their training was superficial and they had no combat experience. The US 5th Fleet, under the command of Raymond A. Spruance, had seven fleet carrier and eight light carriers. On 19 June Ozawa launched four successive air strikes against the USN ships but they were all destroyed by the combination of radar, new carrier-borne fighters (F6F Hellcat), and pilots that were better-trained and had much combat experience. That same day USN submarines managed to sink the new Japanese aircraft carrier Taihō as well as Shōkaku. The next day, a USN counter-attack sank carrier Hiyō and damaged three more carriers. Overall the Japanese lost more than four hundred aircraft with their newly trained aircrew.

Battle of Leyte Gulf

After disastrous losses at the Battle of the Philippine Sea, the Japanese carrier force was again practically without aircrew and aircraft. This meant that at the Battle of Leyte Gulf the IJN carrier force was only used as a decoy force where it was ultimately destroyed, the battle that saw the last Kidō Butai survivor, Zuikaku, along with Zuiho, Chiyoda and Chitose succumbing to US air attacks of Admiral William F. Halsey's Task Force 38.

References

Citations

Bibliography

External links

• Kidō Butai at Combined Fleet.com
• Air Units of the Imperial Japanese Navy, Globalsecurity.com

Imperial Japanese Navy air units
Air Fleet	1 2 3 5 10 11 12 13 14
Air Flotilla	11 12 13 21 22 23 24 25 26 27 28 29 32 51 53 61 62 71 72 101
Combined Air Group	1 2 3 4 11 12 13 14 15 18 19 20 21 22 23 24
Air Group	1 2 3 4 5 6 7 8 11 12 13 14 15 16 17 18 19 21 22 23 31 32 33 35 36 40
Naval Air Group (Numbered name)	121 131 132 133 141 151 153 171 201 202 203 204 205 210 221 251 252 253 254 256 261 263 265 281 301 302 312 321 322 331 332 341 343 345 352 361 381 452 453 501 502 503 521 522 523 524 531 541 551 552 553 582 601 631 634 652 653 701 702 703 705 706 707 721 722 723 724 725 732 751 752 753 755 761 762 763 765 801 802 851 901 902 903 931 932 933 934 936 938 951 952 953 954 955 956 958 1001 1021 1022 1023 1081
Naval Air Group (Place name)	Expeditionary unit Chitose Genzan (I) Kanoya (I) Kisarazu Mihoro Misawa (I) Takao (I) Tainan (I) Tōkō Yokohama Patrol / Defensive unit Chichijima Chinkai Kure Kushimoto Maizuru Okinawa Ōminato Saeki Sasebo Tateyama Toyohashi (I) Yokosuka Practice unit Atsugi Genzan (II) Hakata Kaikō Kanoya (II) Komatsushima Kōnoike Matsushima Miyazaki Nagoya Ōi Ōita Ōmura San'a Seitō Shanhai Shinchiku Sukumo Suzuka Tainan (II) Takao (II) Tokushima Toyohashi (II) Tsuiki (I) Tsukuba Usa Yatabe Basic training unit Amakusa Fukuyama Himeji Hyakurihara Isahaya Iwakuni (I) Izumi 1st Izumi Jinmachi Kan'onji Kashima Kitaura Kobi Kōchi Kokubu 2nd Kōriyama Kōshū 2nd Kōwa 2nd Miho Mineyama 3rd Okazaki Ōryū Ōtsu Pusan Saijō 2nd Takao Takuma Tōkyō Tsuiki (II) Yamato Mechanic training unit Fujisawa Hitoyoshi 2nd Izumi 2nd Kanoya Katori Kōriyama 1st Kōriyama Kōwa 1st Kōwa Kushira Oihama Okazaki 1st Okazaki 2nd Okazaki Sagamino 1st Sagamino 2nd Sagamino Sunosaki 2nd Tainan Tarumi Taura Preparatory flight training unit Fukuoka Iwakuni (II) Kagoshima Kasumigaura Kofuji Komatsu Kōyasan Kurashiki Matsuyama Mie Miho 1st Miho Misawa (II) Nara Nishinomiya Seto Shiga Shimizu Takarazuka Tsuchiura Urado Uwajima
Naval Air Group (Regional name)	Chōsen Chūhi Chūshi Gōhoku Higashikarorin Hitō Hokuhi Hokutai Hokutō Inshi Kantō Kinki Kyūshū Marai Mariana Naikai Nanpi Nanpōshotō Nanseishotō Nantai Nishikarorin Ōu Saikai San'in Taiwan Tōin Tōkai
Flying squadron	Fighter Squadron 161 162 163 164 165 166 167 301 302 303 304 305 306 307 308 309 310 311 312 313 315 316 317 318 351 401 402 403 407 601 602 603 701 804 812 851 901 902 Attack Squadron 1 3 5 102 103 105 107 161 251 252 253 254 256 262 263 401 405 406 501 701 702 703 704 705 706 707 708 709 711 Reconnaissance Squadron 3 4 11 12 61 101 102 301 302
(I) First generation (II) Second generation