Pearl Harbour War

The Pearl Harbour War was a war between the Japanese Empire and the United States of America that lasted between 1941 and 1948. While the first four years of the conflict occurred in tandem with the Second European War, the conflict did continue for an additional two years after the end of the Second European War.

Bombing of Pearl Harbour
On December 7th, 1941, an attack was coordinated by the Japanese Empire on Pearl Harbour, an American harbour and embassy to Hawaii. This caused the United States of America and the Kingdom of Hawaii to declare war on the Japanese Empire and subsequently enter the Second European War.

Four-Way Agreement
The United States began experimenting with the idea of nuclear weapons in the early 1940s. With the advent of the Clinton Engineer Works and Project Y, The United States began to consider the utilisation of nuclear weapons on Japanese territory. However, 1943 saw the signing of The Four-Way Agreement which effectively banned nuclear weapons and shut down any further continuation of the Manhattan Project. President Roosevelt was initially reluctant to sign the treaty for fear of losing an advantage in the Pearl Harbour War but eventually signed it after two days of negotiation with the other leaders in Constantinople. It is thought that with the usage of nuclear weapons, the United States could have ended the Pearl Harbour war up to three years earlier at the expense of the death of hundreds of thousands of Japanese civilians and the decimation of some Japanese cities.

Japanese Sieges on the West Coast of the United States
Between 1944 and 1946, many battles would occur on the west coast of the United States, such as the Battle of San Diego and the the Battle of Astoria. While the Japanese were successful in occupying numerous small territories along the west coast, they would ultimately lose them as a result of the Treaty of Seattle.

Japanese Capture of Ni'ihau and Kauai
In October of 1946, Japan captured the islands of Ni'ihau and Kauai in Hawaii. In retaliation, the United States began military initiatives to capture southern parts of Japan in January of 1947 with the invasion of Minamiosumi.

American Capture of Kyushu and Shikoku
Throughout 1947, the United States led several military campaigns on the islands of Kyushu and Shikoku. The capture of Nagasaki in November of 1947 led the world to believe that Japan would soon surrender and the war would be over by the new year. Incredulously, Japan did not request peace negotiations for almost another four months.

End of the War
Main Article: Treaty of Seattle

On February 24th, 1948, Hirohito arrived in Seattle for peace negotiations with President Harry S. Truman and Hawaiian king Lunalilo II. Negotiations lasted for five days. Hirohito was reported to have been "a nightmare" during the negotiations, making ridiculous demands and causing sessions to last well into the early hours of the morning. The treaty was ultimately signed on February 29th, 1948. Japan ceded all of its occupied territories on the west coast back to the United States, and the islands of Kyushu and Shikoku were declared autonomous dependencies of the United States. Although much of the two islands were now under the control of the United States, Japan was able to have the prefectures of Fukuoka and Kagawa ceded back to the Empire. Ni'ihau and Kauai were ceded back to Hawaii.