This was a US unrealised plan for the seizure of the rest of the Volcano and Bonin islands groups after the ‘Detachment’ seizure of Iwo Jima (February 1945).
The Japanese Nanpo-shoto (three groups of islands) is a chain of islands extending some 750 miles (1205 km) to the south from Honshu in the Japanese some islands toward the Mariana islands group. As suggested by its Japanese name, the chain has three main groups of islands: the most northerly of these is the Izut-shoto, which included the island of Hachijo Jima; farther to the south is the Ogasawara-shoto or Bonin islands group; and at the southern end of the chain is the Kazan-retto or Volcano islands group, of which the most important in World War II was Iwo Jima.
The Bonin islands group lies some 620 miles (1000 km) to the south of Tokyo and in the area to the north of the Volcano islands group. The group numbers more than 30 islands with a total land area of about 32 sq miles (84 km˛). Rugged and only lightly populated, the islands were fortified by the Japanese during the war, and their most important facility was the small anchorage at Chichi-jima, which was attacked from the air several times, especially during the 'Forager' campaign against the Mariana islands group and 'Detachment' assault on Iwo Jima.
The Volcano islands group comprises four islands, which are active volcanoes lying atop an island arc that extends as far to the south as the Mariana islands group, and have an area of 12.57 sq miles (32.55 km˛).
After the success of 'Detachment' in taking Iwo Jima, the US forces remained content merely to blockade the other islands of the two groups for the rest of the war. The Japanese army forces on Chichi-jima and the Bonin islands group surrendered to a US Navy force commanded by Commodore J. H. Magruder on 3 September 1945, and the Japanese navy forces were surrendered by Vice Admiral Kunizo Mori to Colonel Presley M. Rixley of the US Marine Corps on 13 December 1945.