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Background

 

Japanese aggression  

Pearl Harbour 

Japanese victories 

Turning point 

No surrender? 

The Manhattan Project 

 
Asia-Pacific in 1945

Japanese aggression

Japan in the 1930s was increasingly aggressive towards neighbouring countries. Japanese soldiers brutally occupied Manchuria in 1931. In January 1932 they attacked Shanghai. The Japanese government was unable to stop them.

In May 1932 a group of junior officers assassinated the Japanese prime minister. After this military men led Japan and by 1936 the Japanese government was under military control. Japan began a full invasion of China in July 1937. It also joined Germany and Italy in the alliance of the Axis Powers.

As well as political and military leaders, Japan had an emperor, Hirohito, who came to the throne in 1926. The belief that he was a divine ruler inspired great loyalty in those who served him. He did not play a direct role in military decisions, but he did support the moves of Japan’s military leaders.

Japan was an island state and needed to import many resources. By invading China, they could exploit the resources of the mainland and make themselves stronger. In 1940 they occupied northern Indochina (now Vietnam, Laos, and Cambodia). This opened the way for them to invade countries further south. Japan’s vision was to be the centre of an economic power that drew on the riches of East Asia.

The USA reacted by freezing Japanese assets and putting an embargo on sending oil to Japan. This was a big problem for Japan and when Prime Minister Konoe could not negotiate a solution with the US, he resigned. The new prime minister was General Tojo. Tojo began preparations for war.

Pearl Harbour

On 7 December 1941 Japanese warplanes launched an attack on the USA’s Pacific fleet at Pearl Harbour in Hawaii. They sank or damaged 19 American ships, destroyed 177 planes and killed 2,335 people. They also attacked British positions in Malaya.

The US government knew an attack was coming, but they were not sure where. The sheer distance of Pearl Harbour from Japan convinced US strategists that the most likely target for a military strike was in the Philippines. Defensive measures were taken at other bases, but Pearl Harbour was left unprotected.

Japanese victories

This successful strike gave the Japanese a considerable advantage. They followed up with a series of victories in the Pacific against British, Australian and American forces. In the early part of 1942 Britain surrendered to the Japanese at Singapore and 62,000 British and Empire troops were taken prisoner. Many Allied soldiers died from mistreatment after they were taken prisoner. Japan went on to conquer the Philippines.

Turning point

The run of Japanese victories came to an end at the Battle of Midway in June 1942. The USA intercepted Japanese codes planning an attack on Midway Island. Their naval and air forces were then able to inflict heavy losses on the Japanese fleet. Until this point the Japanese Navy had been supreme, but now the US Navy controlled the Pacific.

Gradually the United States gained the upper hand with successes including the Japanese withdrawal from Guadalcanal in February 1943 and the victory in the Philippine Sea in June 1944. By the spring of 1945 an attack on Japan itself was possible.

No surrender?

The war in the Pacific was expensive for the USA. Every Japanese-held island they captured put up fierce resistance. For example, on Iwo Jima, a small island 660 miles south of Tokyo, the Japanese built an elaborate network of defensive tunnels. It took five weeks of bitter fighting at a cost of more than 24,000 casualties before the USA took Iwo Jima. In taking another island, Okinawa, the US incurred a further 20,195 dead and 55,162 wounded.

The sense that Japan would fight to the end was heightened by the tactic of kamikaze in which young Japanese men gave their lives by flying planes directly at US shipping in suicide missions. Furthermore, even though Japan's forces had suffered irreversible losses, there were those in government who remained determined to resist at all costs.

It was now clear that further 'island-hopping' through the Pacific would cost many American lives. In March 1945, in order to secure a Japanese surrender, the US launched a series of low-level air raids on Japan’s main cities, flattening buildings and killing thousands of civilians. This intensive bombing campaign was still going on when President Truman entered the White House and was told that the secret mission to develop an atomic bomb was nearing its conclusion.

The Manhattan Project

Throughout World War 2, German and American scientists raced to be the first to build an atomic bomb. The British slowed down the German work by destroying their laboratories in Norway. The Germans had not developed a working bomb by May 1945, when they lost the war.

The American effort was code-named the Manhattan Project and the team of scientists was led by Robert Oppenheimer. The Manhattan Project was top secret and was based in the remote village of Los Alamos, New Mexico.

In July 1945 they carried out an atomic explosion for the first time. It was estimated that at the centre of the explosion the temperature reached 100 million degrees Fahrenheit. (A hot summer’s day in Britain is about 80 degrees Fahrenheit.) A mushroom-shaped cloud rose to a level of 41,000 feet. The power of the bomb was staggering.

The decision whether or not to use the bomb rested with Harry Truman. He became president following the death of Franklin D. Roosevelt in April 1945. Only then was he informed of the Manhattan Project and the atomic weapons that were at his disposal.