War Against Japan

The war against Japan—also called the Pacific War—took place in the context of the Second World War. The Pacific War began in December 1941 after Japan attacked Pearl Harbor, and ended in September 1945 with Japan's surrender and formal American occupation until 1952.

Japan's surrender took place two weeks after the U.S. strikes on Hiroshima and Nagasaki with atomic bombs—the first-ever usage of such weapons in history:ñ

Fig. 1 - U.S. World War II propaganda poster against Japan with racist overtones, by James Montgomery Flagg.

War against Japan: Origins

Until December 1941, the United States maintained formal neutrality in the Second World War. However, it aided Britain and the Soviet Union with supplies against Nazi Germany through Lend-Lease. The United States also imposed strict sanctions on Japan, which invaded China, expanded into Southeast Asia, and threatened the American colony of the Philippines. The sanctions prevented Japan from buying oil and steel, whereas the country's assets were frozen in America.

Japanese Imperialism

Between 1910 and 1945, Japan was an empire led by Emperor Hirohito (1901-1989). The country conquered many colonies abroad, including:

• Korea
• Manchuria (China)
• Cambodia
• Laos
• Thailand
• Vietnam
• Burma

Japan called these colonies the Greater East Asia Co-Prosperity Sphere, used to improve its economic situation caused by the Great Depression, growing population, and limited supplies.

Japanese Militarism

20th-century Japanese militarism was an essential aspect of the Second World War. Militarism was linked to patriotism, honor, the importance of the armed forces to a country's well-being, and serving the state. Militarism permeated every part of Japanese society until 1945, ranging from policy to aesthetics to public schools.

Fig. 3 - Baby Crown Prince Michinomiya Hirohito holding the imperial flag of Japan, 1902, Asahi Shimbun.

Japanese War Crimes

An extreme consequence of Japanese imperialism and militarism was war crimes. Examples include the Rape of Nanking (1937-1938) and the Bataan Death March (1942).

U.S. War against Japan

Between 1941 and 1945, the U.S. was involved in the Asia-Pacific, European, and North African theaters of war. As a result, the U.S. could not participate in a full-scale land war against the Japanese. However, President Roosevelt used up to 40% of the overall war effort in the Asia-Pacific. When Roosevelt died in April 1945, President Harry Truman led the fighting.

Fig. 4 - A B-25 bomber taking off from USS Hornet, Doolittle Raid, April 1942.

The Americans relied on superior air power, the Navy, and the Marines. U.S. goal was to push out the Japanese from their colonies. The U.S. also wanted to encourage the establishment of governments friendly to the U.S. in the region and discourage European re-colonization.

U.S. Declaration of War against Japan

On December 7, 1941, Japan bombed Pearl Harbor, Hawaii. The Americans responded the next day by declaring war on Japan and entering the Second World War.

Fig. 5 - Torpedo attack, Pearl Harbor strikes, a photograph captured from a Japanese plane, December 7, 1941.

Timeline: American War against Japan (World War II)

The war against Japan involved many famous battles, such as the Battles of Midway, Iwo Jima, and Okinawa. One of the key personalities was the General of the U.S. Army, Douglas MacArthur (1880-1964), who later led the occupation of postwar Japan. In addition, the Allied conferences and Japan's formal surrender were essential to understanding this war.

Fig. 6 - General Douglas MacArthur signed Japan's formal surrender on September 2, 1945, in Tokyo Bay.

World War II Alliances

The Allies fought against the Axis powers during the Second World War (1939-1945).

One of the Allies, China, was also engaged in the Second Sino-Japanese War (1937–1945).

Potsdam Conference

The Potsdam Conference (July 17-August 2, 1945) in Germany was the first conference after victory in Europe. The Big Three decided upon the Soviet entry into the war and the terms of the Japanese surrender.

Soviet War against Japan

On August 8, 1945, the Soviet Union declared war on Japan. After the Allies won the war in Europe in May 1945, the Soviet Union could dedicate its Red Army to Manchuria (China), the Kuril Islands, and Korea. Led by Marshal Alexander Vasilevsky, the Soviet Union sent the already failing Japanese into retreat, losing only approximately 8,000 troops–in comparison, the Japanese lost almost eighty thousand troops.

Japan's Surrender

On August 15, 1945, Emperor Hirohito announced Japan's surrender on the radio. On September 2, Japan signed the formal paperwork on the U.S. Battleship Missouri in Tokyo Bay. The American side was led by the Supreme Commander of the Allied Powers (SCAP), General Douglas MacArthur. The Japanese side comprised General Yoshijiro Umezu and the statesman Mamoru Shigemitsu.

The Air War against Japan

The superior air power of the U.S. and the support of the Navy were vital in the Pacific War. Later, these two components proved essential for other U.S. wars.

Fig. 8 - Residential destruction in Tokyo, March 1945, the Chuo City Peaceful Prayer Virtual Museum.

Nuclear Strikes on Hiroshima and Nagasaki

On August 6 and 9, the U.S. used nuclear weapons for the first and only time in history. The attack was against the Japanese cities Hiroshima and Nagasaki, respectively. It was already clear that Japan had lost. Its failure to surrender resulted from its cultural code rather than a willingness to fight, especially after the Soviets joined the war on August 8. The strikes led to a massive civilian death toll and long-lasting radiation effects. The U.S. censored the images of the aftermath until the 1950s.

Fig. 9 - The aftermath of the nuclear strikes on what is now the Atomic Bomb Dome, by Shigeo Hayashi, October 1945.

Fig. 9 - The aftermath of the nuclear strikes on what is now the Atomic Bomb Dome, by Shigeo Hayashi, October 1945.

Some historians argue that President Truman wanted to show off the new American weapons to the Soviet Union—its new ideological rival in the Cold War (1945-1991).

After the War against Japan

Japan was under American occupation as it transitioned from a militarist empire to a peaceful democracy. Its civilians also recovered from the horrors of war, malnutrition, and homelessness.

American Occupation

From 1945-1952, the U.S. formally occupied Japan with two overarching goals:

• Demilitarization
• Democratization

The U.S. sought to demilitarize Japan by reducing its military and arms in parallel with postwar Germany. The occupying power also wanted to mold Japan in its image as a western democracy. At the same time, the Americans, led by General MacArthur, condescendingly treated the Japanese.

The Americans also relied on censorship and crushed the Japanese left-wing movements. The formal occupation ended in 1952, but the Americans maintained their military bases, such as the one in Okinawa.