International relations (1919–1939)

International relations (1919–1939) covers the main interactions that shaped world history during the interwar period, focusing on diplomacy and economic connections. This time followed the diplomatic history of World War I and led up to the start of World War II.

Key events included solving issues left from the war, like reparations owed by Germany and setting new boundaries. There was also American involvement in European finances and efforts to reduce weapons. The League of Nations tried to help but faced many challenges.

The period saw new countries forming and struggling to relate to older nations. There was also tension between the Soviet Union and other countries with different economic systems. Efforts for peace and reducing weapons were made, but the Great Depression starting in 1929 made things harder.

The world also faced problems like the collapse of international trade and the fall of democratic governments. Japan became more aggressive toward China, and fascist leaders in Italy and Germany made bold moves. The Spanish Civil War was another conflict during this time.

As tensions grew, countries like Germany expanded into areas such as the Rhineland, Austria, and Czechoslovakia. This period ended with desperate efforts to rearm as another world war seemed closer.

Background

Main articles: Diplomatic history of World War I, Aftermath of World War I, Interwar period, and International relations (1814–1919)

The years after World War I were busy with countries trying to fix problems from the war. They worked on issues like money owed by Germany, setting new borders, and trying to keep peace through groups like the League of Nations. Many new countries formed, and there were big changes in how countries traded and worked together.

Peace and disarmament

There were no large wars in the 1920s. Small conflicts happened, but they did not grow into bigger problems. Many countries worked hard for peace. Leaders believed that working together through groups like the League of Nations could help solve problems without fighting.

The League of Nations was created in 1919 to keep peace and help countries talk out their differences. However, some big countries like the United States, Germany, and the Soviet Union did not join at first, which made it harder for the League to work well. The League tried to stop fights, like when Japan invaded Manchuria and when Italy invaded Ethiopia, but it had trouble enforcing its decisions.

Countries also tried to reduce their weapons. The Washington Naval Conference in 1921 led to treaties that limited the size of navies. Later, the London Naval Treaty in 1930 continued these limits. These agreements helped keep peace in the 1920s but were not renewed later as the world became more unstable.

In 1925, the Locarno Treaties helped improve relations between European countries, making Germany feel more accepted. Unfortunately, these peaceful efforts did not last, as Nazi Germany later ignored them. In 1928, many countries signed the Kellogg–Briand Pact, promising not to use war to solve problems. Although it was not always effective, it later influenced rules for peace after World War II.

The use of poison gas in war was also outlawed by the Geneva Protocol in 1925, which most countries agreed to follow.

Europe

The period between the two World Wars was marked by significant changes in international relations and diplomacy across Europe. The United Kingdom faced challenges balancing its global influence while dealing with rising powers like the United States. France focused on building alliances to counter the threat from Germany. The rise of fascist movements in Italy and Germany introduced aggressive new policies, while the Soviet Union navigated its relationships with both capitalist and fascist states.

The Great Depression of the 1930s had a profound impact, leading to economic difficulties and political instability. Many countries turned to authoritarian governments, and efforts at disarmament often failed. The League of Nations struggled to maintain peace, and tensions grew that eventually led to World War II. This era saw the emergence of new nations in Eastern Europe and significant shifts in the balance of power, setting the stage for the global conflicts of the mid-20th century.

Main articles: History of the foreign relations of the United Kingdom and United Kingdom and the League of Nations

Further information: Timeline of British diplomatic history and History of the United Kingdom

United Kingdom

The UK faced challenges in maintaining its influence during the 1920s and 1930s. It often had to rely on the United States for financial support. Key events included its role at the Paris Peace Conference of 1919, where efforts were made to moderate harsh demands on Germany. The UK was an active member of the League of Nations, though with mixed results.

Political instability at home affected foreign policy, and relationships with the Dominions—Canada, Australia, South Africa, and New Zealand—evolved as they gained more independence. The UK sought peace through naval arms limitation treaties and the Locarno treaties of 1925, aiming to stabilize relations with Germany.

The Great Depression strained the economy, leading to a shift towards imperial preference and increased tariffs. Disarmament efforts stalled, and most major nations began rearming. The UK pursued a policy of appeasement towards Germany and Italy in the late 1930s, hoping to avoid war, but this ultimately failed as tensions escalated.

Further information: Appeasement and European foreign policy of the Chamberlain ministry

France

France's main goal was to form alliances against the threat from Germany, particularly with Britain and smaller Central European countries. In the 1920s, France engaged in active interventions, such as in the Rhineland, and supported Poland and Spain. The Maginot Line was built as a defensive barrier against German attacks.

In the 1930s, France faced economic difficulties and political unrest. Appeasement became a policy as Germany grew stronger, leading to concessions such as the Munich Agreement of 1938. France also nationalized arms suppliers and increased military rearmament in the late 1930s.

Fascism

Fascism emerged as a powerful political movement in Europe after World War I, particularly in Italy and Germany. It was characterized by authoritarian nationalism, opposition to liberalism and Marxism, and the use of violence to achieve political goals. Fascist states like Italy and Germany pursued aggressive foreign policies and formed alliances that contributed to the outbreak of World War II.

Germany

After World War I, Germany became a republic but faced significant internal and external challenges. The Treaty of Versailles imposed heavy reparations and territorial losses, leading to economic hardship and political instability. The Weimar Republic struggled with uprisings from both left and right.

With the rise of the Nazi Party in 1933, Germany transformed into a dictatorship under Adolf Hitler. Hitler pursued an aggressive foreign policy, remilitarizing the Rhineland, annexing Austria and Czechoslovakia, and eventually invading Poland in 1939, which led to the start of World War II.

Eastern Europe

The end of World War I led to the creation of new nations in Eastern Europe as the Russian, Austro-Hungarian, and Ottoman Empires dissolved. Countries like Poland, Czechoslovakia, and Yugoslavia emerged, though many faced ethnic tensions and political instability. The Baltic states—Estonia, Latvia, and Lithuania—gained independence from Russia but were later absorbed into the Soviet Union.

Soviet Union

The Soviet Union, formed after the Russian Revolution, faced intervention from Allied powers during the Russian Civil War. In the 1920s, it pursued trade agreements and secretly allowed Germany to train military forces. Under Joseph Stalin, the USSR adopted the policy of "Socialism in One Country" and later formed the "Popular Front" against fascism.

In the late 1930s, the USSR attempted to form alliances with Western powers but instead signed a pact with Germany, dividing Eastern Europe and supplying resources to Germany before being invaded in 1941.

Spanish Civil War

The Spanish Civil War highlighted Europe's political divisions, with right-wing Nationalists supported by fascist Italy and Nazi Germany facing left-wing Republicans backed by the Soviet Union and international volunteers. The war ended with the victory of the Nationalists under Francisco Franco, who established an authoritarian regime that maintained neutrality during World War II.

Main article: Fascism in Europe

Main article: Weimar Republic

United States

Main articles: History of U.S. foreign policy, 1913–1933 and Foreign policy of the Franklin D. Roosevelt administration

In the 1920s, the United States played an active role in world affairs. American leaders helped solve problems in Europe and Asia, even though the U.S. did not join the League of Nations. The country used its money and influence to support peace and help other nations recover from World War I.

American leaders focused on reducing the number of weapons, especially ships, to prevent future wars. They also worked to help Germany pay back money it owed after the war, creating plans that made payments easier over time. The U.S. also changed its policy toward Latin America, promising not to interfere in the affairs of other countries.

Latin America

The United States changed its foreign policy with the Good Neighbor Policy, moving away from interfering in Latin American countries. American troops left places like Haiti, and new agreements with Cuba and Panama ended special US control over them. In 1933, the Montevideo Convention was signed, promising not to get involved in the internal matters of Latin American nations without their agreement. This meant Cuba was free from US laws that limited its independence.

The Great Depression in Latin America hurt many countries because the demand for their raw materials dropped sharply, especially in Chile, Peru, and Bolivia. Leaders and thinkers in Latin America began to support import substitution industrialization, aiming to build stronger, self-reliant economies with their own industries. Even though this sometimes threatened US business interests, President Roosevelt followed the Good Neighbor policy and did not stop countries like Mexico from taking control of foreign companies, including oil companies, to build their own state-run Pemex.

Brazil

In Brazil, a revolution in 1930 ended the rule of coffee plantation owners and brought in leaders focused on industry and modernization. By 1933, new industries helped improve the economy, gaining support from American investors. Brazil worried about Argentina's attempts to weaken it and worked more closely with the United States. Later, during World War II, Brazil became a strong ally of the United States.

Border disputes and warfare

While many small border disagreements happened, only one grew into a major war: the Chaco War from 1932 to 1935. Bolivia and Paraguay fought over the Gran Chaco region, where oil was found. Despite Bolivia's larger army, Paraguay had better planning and won most of the battles. The war ended with a peace treaty giving most of the land to Paraguay.

Asia and Africa

Egypt

Main article: Kingdom of Egypt

In 1922, the United Kingdom declared Egypt independent, though it kept control over important areas like the Suez Canal and military matters. Egypt’s King Fuad passed away in 1936, and King Farouk took the throne at just sixteen years old. Farouk later signed a treaty with Britain, agreeing that British troops would leave Egypt by 1949, except for those stationed at the Suez Canal.

Japan

Further information: Foreign relations of Meiji Japan, Second Sino-Japanese War, and Japan–Russia relations

During this time, Japan’s military grew very powerful and took control of the government. They pursued aggressive policies, especially toward China. In 1931, Japanese officers took over Manchuria, creating a new state called Manchukuo. This led Japan to leave the League of Nations. Japan’s ambitions grew, and in 1937, full-scale war broke out between Japan and China. Japan aimed to control much of Asia under what they called the “Greater East Asia Co-Prosperity Sphere.” The United States and other countries opposed Japan’s actions and placed restrictions on them.

China

Main articles: History of the Republic of China and Warlord Era

After overthrowing the last emperor in 1911, China faced chaos with local leaders called warlords. A leader named Sun Yat-sen tried to unite the country but died in 1925. Chiang Kai-shek took over and began to bring parts of China under central control. In 1927, he turned against communist groups and chased them across the country during what is known as the Long March. Meanwhile, Japan invaded parts of China, leading to widespread conflict. Despite challenges, China received support from many countries, especially the United States and Britain.

India

Main articles: Imperial Conferences and League of Nations

India took part in the talks that ended World War I and signed the Treaty of Versailles separately from the United Kingdom. This allowed India to join the League of Nations in 1920. India also attended meetings of the British Empire to discuss issues like trade and the rights of Indians living abroad. One big issue was the treatment of Indians in South Africa, where laws often discriminated against them. India worked with South Africa to improve conditions, though challenges remained.

Coming of World War II

Main articles: Causes of World War II and Diplomatic history of World War II

Wars

• Turkish War of Independence
  • Greco-Turkish War (May 1919 – October 1922)
  • Turkish–Armenian War (September–December 1920)
  • Franco-Turkish War (December 1918 – October 1921)
  • Royalist and separatist revolts (1919–1923)
• Unification of Saudi Arabia
  • Rashidi-Saudi War (1903–1921)
  • Kuwait-Saudi War (1919–1920)
  • Hejaz-Saudi War (1919–1925)
  • Transjordan-Saudi War (1922–1924)
• Polish–Soviet War (February 1919 – March 1921)
• Irish War of Independence (January 1919 – July 1921)
• Iraqi revolt against the British (1920)
• Rif War (1920–1927)
• Pacification of Libya (1923–1932)