Japan’s aims in World War II were to establish and maintain a dominant sphere of influence in the Pacific region by creating an Asian Co-Prosperity Sphere that would provide a buffer from foreign powers and expand its economic, political, and military territorially and economically. Specifically, Japan sought to neutralize the power of Western nations in East Asia, seize resources in the region, and acquire new territories to expand its imperial empire.
At the outset of World War II, Japan had already acquired Manchuria from China in 1931 and had exerted considerable influence in China through the puppet state of Manchukuo. Still seeking to further expand their Empire, in 1937 Japan commenced an offensive against China proper. The Japanese sought to gain control of much of the eastern Chinese coast, with Shanghai being a key city they wanted to capture. To do so, they adopted a strategy of ruthless military force and “total war” against the civilian population, looting and pillaging towns as they advanced.
In 1940, Japan wrote the Hakko Ichiu (“The Eight Corners of the World Under One Roof”) doctrine, formulated by then-prime minister Konoe Fumimaro. It was intended to increase Japanese presence in Asia and the Pacific by establishing a cooperative relationship with sympathetic countries and bring them under its domination. As part of this Greater East Asia Co-Prosperity Sphere, Japan desired to seize colonial possessions from European powers like Britain, France, and the Netherlands. It also wanted to gain access to resources such as oil, rubber, tin, iron, and other strategic materials from Southeast Asia, as well as establishing new bases and naval ports to extend its naval power in the Pacific.
In 1941, Japan undertook a surprise attack on Pearl Harbor in Hawaii. This attack was meant to ensure that the United States would not interfere with Japanese ambitions in the Pacific, as the Japanese believed that U.S. intervention was inevitable as the American public had become increasingly hostile to Japanese aggression in China. The attack did not do enough to disable the US Pacific fleet, however, and the US soon joined the war against Japan.
Despite the attack on Pearl Harbor, Japan initially gained the upper hand in the Pacific following the Battle of Midway, where the Japanese navy managed to turn back the US Pacific fleet. This victory allowed Japan to continue its expansion. In 1942, it occupied the Philippines, Guam, Wake Island, New Guinea, and the Solomon Islands, and took control of most of the South Pacific islands.
The US staged a successful counteroffensive in 1943, beginning with the Guadalcanal campaign, which saw the US emerge victorious in the decisive Battle of Leyte Gulf. The South Pacific began to be slowly taken back by the Allies, with the Japanese retreating back to mainland Japan. However, Japan refused to surrender and still sought to defend their newly acquired territory, resulting in some of the bloodiest fighting of the war.
By 1945, with Allied support steadily increasing, Japan faced overwhelming odds. The US dropped atomic bombs on Hiroshima and Nagasaki and Japan eventually surrendered unconditionally on August 15, 1945.
Despite their defeat, the Japanese had achieved many of their goals, acquiring substantial new territory and resources in the Pacific, while forcing the US and other western nations out of East Asia. In addition, their legacy can still be seen in the former Co-Prosperity Sphere countries, where Japan has maintained a significant level of influence to this day. Ultimately, Japan’s war aims were ambitious but unsuccessful, as the US ultimately prevented it from becoming the dominant power in East Asia.