Amphibious Brigades (Imperial Japanese Army)

The 1st Amphibious Brigade (海上機動第1旅団) was created in 1943 and dissolved in 1945. Its tsūshōgō code was “Storm 3139” ( 駆3139, Kakeru 3139 ).

The 1st Amphibious Brigade was established on 16 November 1943 under the command of Lieutenant General Yoshimi Nishida out of the Manchukuo-based IJA 3rd Independent Garrison Unit. In mid-December 1943, the brigade embarked and arrived shortly afterwards at Truk, where it was placed under the IJN 4th Fleet.[1] Imperial General Headquarters assigned it to Eniwetok to counter an expected Allied invasion: however, the brigade lost in the sinking of the Aikoku Maru at Truck on 17 February 1944 during Operation Hailstone. Another 800 men, including Lieutenant General Nishida were annihilated during the Battle of Eniwetok from 17 to 23 February 1944 by the United States Marine Corps. The remaining men and transports were sent to Palau and were incorporated into the IJA 53rd Independent Mixed Brigade in May 1944.

The 2nd Amphibious Brigade (海上機動第2旅団) was created on 16 November 1943 and dissolved in 1945. Its tsūshōgō code was “Patrol3189” ( 巡 3189, Meguru 3189 ).

Although it was not planned to set up the 2nd Amphibious Brigade until 1944, the schedule was advanced to November 1943 due to the success of the Allied Operation Cartwheel. The 2nd Amphibious Brigade was established out of the Manchukuo-based IJA 5th Independent Garrison Unit with the staff from the IJA 29th Division.[1] On 11 April 1944, the 2nd Amphibious Brigade was assigned to the Southern Expeditionary Army Group and was sent to the Philippines in May, but without their armored company. It was then transferred in June to the Vogelkop peninsula in western New Guinea, where he came under the command of the IJA 2nd Army. En route, its supply vessel was sunk by an American submarine, causing the loss of most of its ammunition and many rifles. During the Battle of Biak from 27 May – 17 August 1944 it was to be sent as reinforcement to the beleaguered Japanese garrison; however, it lacked the transport to reach the island.[1] The 2nd Amphibious Brigade remained in Sorong for the duration of the war, where, weakened by malnutrition and disease, it surrendered in August 1945.[1] Some 180 members of the brigade who survived the sinking of the supply ship were stranded in Zamboanga and were killed during the Battle of Mindanao.

The 3rd Amphibious Brigade (海上機動第3旅団) was created in May 1944 and dissolved in 1945. Its tsūshōgō code was “Thunder 12630” ( 轟 12630, Todoroku 12630 ).

The formation of the 3rd Amphibious Brigade took place in May 1944 under the command of Colonel Ikeda Einosuke in Shumshu in the Kuril Islands from elements of the Chishima 1st Reserve Group. It was structured identically as the 1st and 2nd Amphibious Brigades.[1] In 1945, it was placed under the command of the IJA 27th Army, and was part of the last-ditch defense of the Japanese archipelago against an anticipated American landing. It was transferred to Hokkaido, followed by Aomori. During the transfer, the transport carrying Colonel Ikeda was sunk by an American submarine, and he was replaced by Colonel Kurashi. On 1 May 1945 it was placed under the command of the IJA 40th Army and transferred to Kyushu, although a portion was sent back as part of a garrison force for Paramushir in the Kuriles. On 23 May 1945 the brigade was dissolved and its men and equipment reinforced the IJA 125th Independent Mixed Brigade, which ended the war in Kagoshima Prefecture.

The 4th Amphibious Brigade (海上機動第4旅団) was created in May 1944 and dissolved in 1945. Its tsūshōgō code was “Expelling 12630” ( 攘15582, Harau 15582 ).

The formation of the 4th Amphibious Brigade took place in May 1944 under the command of Major General Torihiko Mineki in Asahikawa, Hokkaido and was structured identically as the 1st and 2nd Amphibious Brigades.[1] Its staff force and three infantry battalions came from the IJA 7th Infantry Division, however, its armored company was based in Morioka and its artillery company was located in Kokura, Kyushu. It was placed under the command of the IJA 27th Army, and was initially assigned to the defense of Iturup in the Kuril islands, but it lacked proper transport and logistics support. In May 1945, it was withdrawn to Honshu and please under the IJA 36th Army as part of the last-ditch defense of the Japanese archipelago against an anticipated American landing. It was based at Saitama Prefecture as part of defenses of Tokyo and was assigned to the IJA 1st Armored Division, but was used exclusively for road maintenance work and to grow crops. The brigade headquarters was at Sakura, Chiba at the end of the war.