Unresolved Tension After World War I

Essential Question

How did continued imperialism and weak international enforcement contribute to global instability in the interwar period?

Post-World War I Tensions

Imperialism Between the World Wars (1919–1939)

After World War I ended in 1918, the period between 1919 and 1939 saw Western powers like Great Britain and France, alongside a rising Japan, cling to or expand their colonial empires despite the war’s upheaval. Imperialism—the practice of one nation exerting power over others through colonization or military conquest—remained a cornerstone of global politics.

Although the war weakened Europe economically and militarily, imperial nations doubled down on their holdings. They were driven by the need for raw materials such as oil, rubber, and cotton to rebuild their economies, strategic bases to secure global trade routes, and national pride to offset domestic instability. This era bridged two global conflicts, as imperial ambitions fueled both exploitation and resistance, setting the stage for World War II.

Britain and France, the war’s victors, retained sprawling empires. Britain controlled India, large portions of Africa, and parts of the Middle East. France held Indochina in Southeast Asia and territories across North and West Africa. Japan, emerging as an industrial power, sought expansion in East Asia and the Pacific, targeting resource-rich regions such as Manchuria for coal and iron to fuel its growing economy.

The 1919 Treaty of Versailles reshuffled imperial territories. Germany’s African colonies, including Tanganyika, were transferred to Britain and France as League of Nations mandates—territories governed under international oversight but often treated as colonies in practice. Meanwhile, colonized peoples in India, Africa, and Southeast Asia increasingly resisted foreign rule, inspired by nationalism—the desire for self-governance—and wartime promises of liberty.

The consequences of interwar imperialism were far-reaching. Britain gained Iraq and Palestine, and France gained Syria under the mandate system. Japan’s expansion into Asia beginning in 1931 destabilized East Asia and heightened tensions with Western powers. Resistance movements gained momentum, weakening imperial authority and laying the groundwork for post–World War II decolonization.

The League of Nations Mandate System

The League of Nations, established in 1920 to promote international peace, created the mandate system to administer territories taken from Germany and the Ottoman Empire after World War I. These mandates were presented as temporary arrangements to guide territories toward independence, reflecting President Woodrow Wilson’s principle of self-determination. However, in practice, mandates often functioned as extensions of European imperial rule.

Mandates were divided into three classes:

Class A territories (such as Iraq) were considered close to independence but required supervision.
Class B territories (such as Tanganyika) required longer oversight.
Class C territories (such as Southwest Africa) were treated as integral parts of the administering power’s territory.

Britain gained control of Palestine and Iraq from the Ottoman Empire and Tanganyika from Germany. France gained Syria and Lebanon and shared control of Togo and Cameroon with Britain.

Although mandates were supposed to operate under League oversight, enforcement was weak. Britain and France exploited resources such as oil in Iraq and cotton in Syria while imposing their legal systems and languages. In Palestine, Britain’s support of Jewish immigration under the 1917 Balfour Declaration—promising a Jewish homeland—intensified tensions between Jewish and Arab populations.

The mandate system contributed to long-term instability. Britain’s rule in Palestine sparked riots in the 1930s. France suppressed uprisings such as the 1925 Druze Revolt in Syria. In Africa, mandates delayed self-rule and intensified anti-colonial sentiment. Rather than dismantling imperialism, the mandate system rebranded it, sustaining European dominance while fostering resistance.

Japanese Imperial Expansion (1931–1945)

Japan’s imperial ambitions intensified between 1931 and 1945 as it sought dominance in East Asia and the Pacific. Japan’s rapid industrialization in the late 19th and early 20th centuries created a demand for resources such as oil, coal, and iron—resources scarce on the Japanese islands.

In 1931, Japan invaded Manchuria following the staged Mukden Incident, using a railway explosion as justification. In 1932, Japan established the puppet state of Manchukuo. The League of Nations condemned the invasion, but Japan withdrew from the League in 1933, signaling its rejection of international oversight.

In 1937, Japan expanded its war into China, capturing major cities such as Nanjing. The Nanjing Massacre resulted in the murder of tens of thousands of Chinese civilians, noncombatants, and prisoners of war by the Imperial Japanese Army. Japan justified its expansion under the concept of the Greater East Asia Co-Prosperity Sphere, claiming to liberate Asia from Western colonial rule while in practice exploiting occupied territories for resources.

By 1940, Manchurian industrial output had tripled. However, Japanese aggression alarmed the United States, which imposed an oil embargo in 1941. These tensions contributed directly to Japan’s attack on Pearl Harbor and the expansion of World War II into the Pacific.

Anti-Imperial Resistance (1919–1939)

Between 1919 and 1939, resistance to imperialism expanded across colonies. Anti-imperial movements drew on nationalism and socialist ideas to challenge European and Japanese rule.

India’s independence movement gained strength during the interwar period. Britain had ruled India under the British Raj since 1858. India contributed over one million soldiers to Britain during World War I, but political reforms were limited. The 1919 Amritsar Massacre, in which British troops killed hundreds of unarmed protesters, intensified anti-colonial sentiment.

The Indian National Congress (INC) intensified campaigns under the leadership of Mohandas Gandhi. Mohandas Gandhi promoted satyagraha—nonviolent resistance grounded in moral force. The 1930 Salt March, a 240-mile journey to produce salt illegally, symbolized defiance of British economic control. Britain responded with arrests and repression. Over 60,000 participants were arrested. However, the movement forced concessions such as the Government of India Act of 1935, which granted limited self-governance.

The 1935 Government of India Act granted partial self-rule, though full independence would not occur until 1947. Gandhi’s nonviolent methods influenced global civil rights movements, including Martin Luther King Jr.’s leadership in the United States.

In Vietnam, Ho Chi Minh founded the Communist Party in 1930, blending Marxism with anti-French nationalism. In Syria, a 1925 revolt against French rule was suppressed with heavy force. In Kenya, the Kikuyu protested land seizures under British colonial policies.

Although full independence often came after World War II, interwar resistance weakened imperial authority and built momentum for future liberation movements.

West African Resistance

In French West Africa, resistance took political and labor-based forms. France’s policy of assimilation aimed to integrate Africans into French culture while extracting resources such as peanuts and cotton.

Workers staged strikes, including the 1930 Senegal railway strike on the Dakar-Niger Railway. The strike lasted from January to May 1930 and resulted in wage increases and improved conditions. Leaders such as Blaise Diagne advocated for African political representation.

Although immediate reforms were limited, these movements laid the groundwork for post–World War II independence movements. Leaders such as Léopold Senghor, who later became Senegal’s first president in 1960, were shaped by interwar activism.

In Summary

The interwar period did not resolve global tensions; instead, it preserved imperial systems under new labels while resistance movements gained momentum. The League of Nations lacked enforcement power, and imperial ambitions continued unchecked. Japanese expansion, European mandates, and rising anti-colonial resistance all contributed to global instability.

The unresolved tensions of the interwar period directly connect to the causes of World War II. Weak international enforcement, ongoing imperialism, and growing nationalist resistance created the unstable environment that made World War II possible.

Discussion Questions

Was the League of Nations doomed to fail from the beginning, or could it have prevented global instability if countries had fully supported it? Use specific examples such as Manchuria or the mandate system.
Do you think the mandate system was truly a step toward independence, or simply imperialism under a different name? Use examples such as Palestine, Iraq, or Syria to support your position.
Was Japanese expansion primarily driven by economic necessity or aggressive nationalism? Use evidence such as Manchuria, resource shortages, or the Greater East Asia Co-Prosperity Sphere.
Did Western imperial powers contribute more to global instability than Japan during the interwar period? Defend your answer with at least two examples.
If stronger action had been taken against Japan in 1931, do you think World War II could have been prevented? Why or why not?

Activity 2: How did continued imperialism and weak international enforcement contribute to global instability in the interwar period?

Using the information from this lesson, create a multi-flow thinking map that explains how imperial expansion and the weakness of international systems increased global instability between 1919 and 1939.

In the center of your thinking map, write:

Global Instability in the Interwar Period (1919–1939)

On the left side, identify and explain:

At least four examples of continued imperialism (examples may include League of Nations mandates, British control of Iraq and Palestine, French rule in Syria, Japanese expansion into Manchuria, or the Greater East Asia Co-Prosperity Sphere).
Provide at least one specific historical example for each.

On the right side, identify and explain:

At least four examples of weak international enforcement or failed peace efforts (examples may include the League of Nations’ inability to stop Japan in Manchuria, failure to enforce mandates fairly, lack of military enforcement power, or Western hesitation to confront aggression).
Provide at least one specific historical example for each.

All explanations must be written in complete sentences. This assignment may be completed on paper or digitally. It will be collected in your portfolio.

Extension Activities

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