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.
[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 Truk 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.
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 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.
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.
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.
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.