​​  🔗===================>> The WWII Japan > Japan Overpowered Submodule <<===​========​==​=======​🔗
prior WWII Japan section:  Iwo Jima and Okinawa                       next WWII Japan section:   Pacific Base Areas
Victory subpages:   Japan Under Attack     Japan Vanquished         
     ––––––––––––––––––––––––– WWII Japan - Victory Submodule –––––––––––––––––––––––––––––––
bigpigeon.us webpage WWII Japan > Victory, © 2025 by Robert A. Christiansen updated by RAC 2 Jun 2025 
​
This webpage provides contextual information for the final few months of the War with Japan.
The Japanese Home Islands
By June 1945, US forces occupied the tiny island of Iwo Jima in the Volcano Islands and the large island of Okinawa on the Ryukyu Island chain. The vise on the Japanese home islands was closing.
The Pre-War Japanese Empire
Before World War II began in 1939, the Japanese Empire had grown to include:
  • Formosa in 1895.
  • Korea in 1905.
  • islands north of the home islands.
  • the Mariana, Caroline, and Marshall Islands to the south, except for Guam, in 1920. (The map is in error; Saipan was occupied by the Japanese.)
  • Manchuria in 1931
  • northeastern China and eastern China seaports, conquests from the Second Sino-Japanese War.

By the time Japan entered World War II in December 1941, Japan had gained control of French Indo-China and enlisted Thailand as a silent partner.
The Japanese Empire - 1939
The Japanese Empire - 1939
Japan, an island nation, lacked the natural resources necesssary for the industrial world. Before the War with Japan began, Japan had cast its eye southward, to the resource-rich area shown on the following map, and especially to the Dutch East Indies (now Indonesia) and to the British possessions on the Malay Peninsula and the island of Borneo. Unfortunately the Philippine Islands, then a United States possession, lay between the home islands and the so-called Southern Resource Area.
The Greater Southeast Asia Area
The Greater Southeast Asia Area
-From December 1941 to May 1942, Japanese forces seized control of the Southern Resource area and forced the surrender of US and Filipino forces in the Philippine Islands. They also pushed their Pacific defensive perimeter to the south and east, moving into the Gilbert Islands, the northern Solomon Islands, the Bismarck Archipelago, and the north coast of New Guinea. French Indo-China (today's Vietnam, Cambodia, and Laos) and Siam (today's Thailand) were occupied without opposition.  By midyear, southern and central Burma lay in Japanese hands.
The Pacific Arena - 1941
The Pacific Arena 1941
For the next three years, Allied forces, primarily from the United States, penetrated the Japanese Empire in two broad offensives:
  • The Southwest Pacific offensive: began in late 1942 in southeastern New Guinea (US Army) and Guadalcanal (US Marine Corps & US Navy), and ended in the Philippine Islands.
  • The Central and Western Pacific Offensive: began in November 1943 in the Gilbert Islands and ended in Okinawa in the spring of 1945.
The Pacific Offensives
The Pacific Offensives
By early summer 1945, the Japanese Empire had almost been broken into two large regions:
  • the Japanese home islands and the occupied portions of East Asia.
  • the Southern Resource Area, including most of Southeast Asia.
Each of these regions still contained a large Japanese Army force. However, material and military couldn't be moved between regions because the Japanese Navy and merchant fleet had been destroyed.

If General MacArthur had stood atop the island fortress of Corregidor in Manila Bay after its liberation on 26 February 1945, he might have visualized the Southern Resource Area, beyond the horizon to the south and west, and still mostly under Japanese occupation.

Although United States policy favored decolonization, the Netherlands, England, and France were anxious to reclaim their colonies. For this purpose, US military support from the Philippines would be most helpful.

In August 1945, with the United States use of atomic bombs and the Russian declaration of war on Japan, the War with Japan ended without the necessity of additional conflict to remove the Japanese from the Southern Resource Area
Japanese Empire 1 Apr 1945
The Japanese Empire 1 Apr 1945
Sources for Big Pigeon's WWII Japan > Japan Overpowered webpage:
  • The Japanese Empire - 1939 map is courtesy of https://www.enemyinmirror.com/map-of-imperial-japan-1939/.
  • The Pacific Arena - 1941 map was found at http://www.emersonkent.com/map_archive/pacific_1941.htm.
  • The Pacific Offensives map was found at https://www.nps.gov/perl/learn/historyculture/pacific-battles.htm.
  • The Japanese Empire 1 Apr 1945 map is courtesy of https://www.ww2online.org/image/map-japanese-holdings-western-pacific-theater-1945. The map shows the two parts of the Japanese Empire remaining at the time of the Okinawa invasion. The map has some inaccuracies. For instance, the Kurile Islands in the north and most of the southern and central Philippines were still in Japanese hands at this time.