On October 1, 1939 the Chitose Kokutai (Chitose Air Group) was formed at Chitose Airfield on Hokkaido in Japan. This was the 21st Kokutai organized and the first formed in Hokkaido, under the Command of Ominato Naval Yard in Aomori Prefecture. On November 15, 1940, the Chitose Kokutai was assigned to the 4th Kokutai.
On January 15, 1941, the Group was assigned to the newly designated 24th Koku Sentai (Air Flotilla). Between June 1941 to August 1941, the Group was engaged in training activities and operated from Saipan, Palau, and the Marshalls Islands in October 1941. During this period, the air group's strength was 36 x Type 96 Attack Bombers / G3M Nell divided into four hiko chutai and 18 x Type 96 Carrier Fighters / A5M4 Claude divided into two hiko chutai. During this period, some bombers carrier fighters also operated from Truk and Tarawa.
In February 1942, Chitose Kokutai was renamed the 4th Kokutai. One chutai was split off from Chitose Kokutai. Another part came from an ad hoc unit formed in December 1941 from pilots from 3rd Kokutai and Tainan Kokutai and sent with Type 96 fighters to Palau. Pilots were a mix of experienced and those hastily pushed through training just before the war broke out to add to operational units.
In October 1941, some of the attack bombers of this Group were dispatched Truk for reconnaissance of Rabaul. A Type 1 Rikko was dispatched to Kwajalein in November to fly reconnaissance over Wake Island. When the war broke out, the group attack bombers began bombing Wake Island and continued bombing there until the island was occupied on December 23, 1941. After the occupation of Wake Island, the Group again engaged in patrol missions.
The bomber section was known as the Ohashi Butai for the commanding officer, Captain Fujiro Ohashi. Equipped with 36 G3M2 Rikko (Nell) bombers, organized into four Hiko Chutai / Buntai. This unit made a bombing raid against Wake Island during December 1941.
Early in January 1942, 18 attack bombers (two hiko chutai) were dispatched to Truk to participate in the operations against Rabaul.
On February 1, 1942, 8 Chitose Kokutai bombers led by Lt. Nakai encountered the U. S. Navy (USN) Task Force led by Adm. W. F. Halsey when they hit a bull's eye strike upon the USS Chester CA-27 and Lt. Nakai made a suicide attack against the USS Enterprise.
During February 1942, equipped with A5M4 Claudes. On February 17, the first six A6M2 Zero were flown from Shoho to
Lakunai Airfield near Rabaul.
On February 10, 1942, one chutai of the Chitose Kokutai was assigned to the 4th Kokutai. By late February 1942 the 4th Kokutai fighter unit had a mixture of both Type 96 (A5M4 Claude) and A6M2 Zeros.
During the middle of February 1942, the Chitose Kokutai began to transition from the Type 96 Attack Bomber (G3M Nell) to the Type 1 Attack Bomber (G4M Betty). The group then continued patrol missions over Malaysia and reconnaissance mission over New Guinea. On March 8, 1942, some planes of the group were dispatched to Wake Airfield to fly patrols. On April 1, 1942, the group moved from the 4th Koku Kantai (Air Fleet) to the 8th Koku Kantai (Air Fleet)
On August 17, 1942, the U. S. Forces attempted to make a surprise landing over to Makin Island using two submarines and Chitose Kokutai bombers were active against the enemy. On September 2, 1942, two bombers were dispatched to Rabaul and participated in bombing missions against Guadalcanal and Port Moresby. The sorties continued until late September 1942. Afterwards, this detachment, to Kwajalein Island on September 23. The group's total strength then advanced to Rabaul on October 26, 1942.
On November 1, 1942 the Imperial Japanese Navy (IJN) renamed air groups with three digit identifiers. The bomber buntai "Ohashi Butai became the 702 Kokutai, the "Ohashi Butai" named for Commanding Officer (C.O.) Captain Fujiro Ohashi became the 703 Kokutai and the Zero buntai became the 201 Kokutai. The fighter buntai was designated the 201 Kokutai.
201 Kokutai (201 Air Group)
On November 1, 1942 the Imperial Japanese Navy (IJN) renamed air groups with three digit identifiers. The 201 Kokutai was formed from the fighter buntai of the 4th Kokutai at Rabaul.
The group used different codes at various dates with three digit aircraft codes for each aircraft.
Tail code S- – ? - November 1, 1942
W1-??? – November 1942 - July 1943
6-??? – Possibly used middle 1943
One of the tail fins in the Blayd collection has tail code 6-136 over an earlier code of W1-187.
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