Move to Global War: Japanese expansion

for ib history paper 1

1931: Mukden Incident and Invasion of Manchuria

What happened: Japanese army officers staged an explosion on the South Manchurian Railway and blamed China.

Japan used this as an excuse to invade Manchuria.

 

Main causes:

• Japan wanted Manchuria’s resources and strategic position.

• The Kwantung Army acted aggressively and independently.

• China was politically divided and weak.

• The Depression made expansion seem like an economic solution.

Responses / effects:

• Japan occupied Manchuria and created the puppet state of Manchukuo in 1932.

• China appealed to the League of Nations instead of defeating Japan militarily.

• The League sent the Lytton Commission, but it moved slowly.

• Japan learned that aggression could succeed with little punishment.

1932-1933: Lytton Report and Japan Leaves the League

What happened: The Lytton Report said Japan was the aggressor and that Manchukuo was not truly independent.

Japan rejected the report and left the League.

 

Main causes:

• The League wanted to investigate but lacked real enforcement power.

• Japan refused to accept outside criticism of its actions in Manchuria.

Responses / effects:

• The League looked weak because it condemned Japan but did not stop it.

• Japan became more isolated from the West

• This encourages further Japanese expansion and showed other aggressors that the League was weak.

 1933-1936: Expansion into Northern China

What happened: Japan increased its influence in northern China through military pressure and agreements that weakened Chinese control.

 

Main causes:

• Japan wanted a buffer zone and greater control near Manchuria.

• Chinese divisions made resistance difficult.

• Japanese militarists believed China could be forced into concessions.

Responses / effects:

• Chinese resentment grew.

• Japan’s influence expanded beyond Manchuria.

• Tension between China and Japan increased, setting up the 1937 war.

1936: Second United Front Begins to Form

What happened: Chinese Nationalists and Communists began moving toward cooperation against Japan, especially after pressure on Chiang Kai-shek.

 

Main causes:

• Japanese aggression created nationalist pressure in China.

• Many Chinese believed internal fighting helped Japan.

• The Xi’an Incident pressured Chiang to prioritize resistance to Japan.

Responses / effects:

• The KMT and CCP temporarily united against Japan.

• Japan faced stronger Chinese resistance than expected.

• The war in China became longer and more expensive for Japan.

1937: Marco Polo Bridge Incident and Sino-Japanese War

What happened: A clash near Beijing escalated into full-scale war between Japan and China.

 

Main causes:

• Japanese forces were already stationed near northern China.

• Militarists expected China to collapse quickly.

• Long-term tension made a local clash easy to escalate.

Responses / effects:

• Japan captured major cities but failed to force China to surrender.

• The war drained Japan’s military and economy.

• International criticism increased, especially after atrocities such as Nanjing.

1937-1941: War in China Drains Japan

What happened: The Sino-Japanese War became a long conflict instead of a quick victory.

 

Main causes:

• Chinese resistance continued through the Nationalists, Communists, and guerrilla fighting.

• Japan needed more resources to continue the war.

• Japan wanted to cut off foreign aid to China.

Responses / effects:

• Japan moved toward Southeast Asia, especially French Indochina.

• The United States became more concerned about Japanese expansion.

• War in China helped push Japan into conflict with the West.

1940: Tripartite Pact

What happened: Japan joined Germany and Italy in the Tripartite Pact.

 

Main causes:

• Japan wanted allies and hoped to deter the United States.

• Germany and Italy also opposed the Western powers.

• Japan’s relations with the U.S. were worsening.

Responses / effects:

• The Axis powers became more formally linked.

• The U.S. saw Japan as a greater threat.

• The European and Asian conflicts became more connected

1940-1941: U.S. Initiatives and Rising Tensions

What happened: The United States responded to Japanese expansion with economic pressure, including restrictions, asset freezes, and eventually an oil embargo.

 

Main causes:

• Japan occupied parts of French Indochina and threatened Southeast Asia.

• The U.S. wanted to defend China and protect its own Pacific interests.

• Japan needed oil and raw materials to continue war.

Responses / effects:

• The oil embargo put Japan in a crisis because it depended on imported oil.

• Japan had to choose between withdrawing or seizing resources by force.

• Diplomacy failed after the Hull Note demanded Japanese withdrawal from China and Indochina

December 1941: Pearl Harbor and Outbreak of War with the West

What happened: Japan attacked Pearl Harbor and also moved against Western colonies in Asia.

 

Main causes:

• Japan wanted to neutralize the U.S. Pacific Fleet.

• The oil embargo made Japan believe time was running out.

• Japanese leaders wanted resources in Southeast Asia and feared U.S. interference.

Responses / effects:

• The United States entered World War II.

• The Sino-Japanese War and European war became part of one global war.

• Japan’s expansion had moved from regional war to global conflict