In the 1930s, most countries of the Americas watched events in Europe and Asia with alarm but had little wish to be dragged into another war. Isolationism isolationism was strong in the United States after the huge losses of the First World War, and Latin American governments were focused on recovering from the Great Depression. Yet the region could not stay separate from world events forever.
The Good Neighbor Policy: From 1933, President Franklin D Roosevelt launched the Good Neighbor policy Good Neighbor policy. The US promised not to intervene militarily in Latin American affairs, reversing decades of interventions under the earlier Roosevelt Corollary and Dollar Diplomacy. In practice this meant withdrawing US Marines from Haiti (1934) and Nicaragua, and accepting Cuba's abrogation of the Platt Amendment (1934), which had allowed US intervention in Cuban affairs.
Roosevelt's goal was hemispheric solidarity: if Latin America trusted the US instead of fearing it, the whole region could present a united front against the growing threat from Nazi Germany, Fascist Italy and Imperial Japan. Germany in particular was expanding trade links with Latin America, and the US worried this could translate into political influence.
- Inter-American diplomacy — a series of conferences brought American states together to coordinate policy
- Montevideo Conference (1933) — the US formally accepted the principle of non-intervention in the affairs of other American states
- Buenos Aires Conference (1936) — agreed on consultation between American states if peace in the region was threatened
- Declaration of Panama (1939) — established a neutrality zone around the Americas after war broke out in Europe
- Act of Havana (1940) — agreed that no European colony in the Americas could be transferred to another hostile power
Cooperation in action: These conferences show the policy working as intended: instead of the US acting alone, American republics increasingly consulted each other. This groundwork mattered enormously once the US entered the war in December 1941, because it meant many Latin American states were already used to coordinating with Washington.
Effects, not just actions: Paper 3 examiners want you to assess effects, not just list events. The Good Neighbor policy's effect was to build enough trust that most of Latin America aligned with the US after Pearl Harbor — contrast this with the suspicion caused by earlier interventions in the region.
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Through the 1930s, the US Congress passed a series of Neutrality Acts (1935, 1936, 1937) banning arms sales and loans to countries at war, reflecting the public mood against repeating 1917. But Roosevelt personally believed Nazi Germany was a direct threat, and he gradually found ways around strict neutrality.
Cash and Carry (1939)
Warring nations could buy US arms if they paid cash and transported the goods themselves — this quietly favoured Britain and France, who controlled the Atlantic.
Destroyers for Bases (1940)
Roosevelt swapped 50 old US destroyers for the right to build US bases on British territory, helping Britain fight German U-boats.
Lend-Lease Act (March 1941)
The US could lend or lease weapons and supplies to any country whose defence was considered vital to US security — mainly Britain and later the USSR.
Pearl Harbor (7 December 1941)
Japan attacked the US naval base in Hawaii, destroying much of the Pacific fleet. The US declared war on Japan the next day; Germany and Italy then declared war on the US.
Cash, Destroyers, Lend, Attacked — each step moved the US closer to war.
Why Pearl Harbor mattered: Until December 1941, isolationist opinion had kept the US out of direct combat. The surprise attack on Pearl Harbor ended the debate overnight — Congress declared war on Japan almost unanimously, and Hitler's decision to declare war on the US (11 December 1941) brought America fully into the European theatre too.
US entry transformed the war both militarily and economically. American factories converted to war production on a massive scale — a process often called the "Arsenal of Democracy" Arsenal of Democracy — supplying tanks, planes and ships to Britain, the USSR and its own forces fighting in both the Pacific and European theatres.
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The guide asks you to study any two countries of the Americas and their involvement in the war. This micro focuses on the United States and Brazil, whose experience shows how a Latin American state moved from cautious neutrality to full military participation.
Brazil's turn towards the Allies: Brazil, under the authoritarian rule of Getúlio Vargas, initially balanced relations with both Germany and the US, since Germany was a major trading partner. But the Good Neighbor policy and US economic incentives — including help building the Volta Redonda steel plant — pulled Brazil towards the Allied side.
| Date | Event |
|---|---|
| 1937–1941 | Vargas plays Germany and the US off each other for economic and military aid, staying formally neutral |
| 1941 | US grants loans for Brazil's steel industry; US forces gain use of Brazilian air and naval bases in the northeast, vital for Atlantic convoy protection |
| August 1942 | German U-boats sink several Brazilian merchant ships; public outrage forces Vargas's hand |
| 22 August 1942 | Brazil declares war on Germany and Italy — the only South American country to send combat troops to Europe |
| 1944–1945 | The Brazilian Expeditionary Force (FEB), around 25,000 troops, fights alongside US Fifth Army in the Italian campaign |
Why Brazil is a strong case study: Brazil shows the Good Neighbor policy paying off directly: years of US goodwill and investment meant that when U-boat attacks forced Brazil to choose a side, it aligned with Washington rather than Berlin. Brazilian bases were also strategically vital, since the northeastern "bulge" of Brazil was the shortest Atlantic crossing point for supplying North Africa.
- Getúlio Vargas — authoritarian president of Brazil (1930–1945) who balanced Germany and the US before committing to the Allies
- Brazilian Expeditionary Force (FEB) — the roughly 25,000 Brazilian troops who fought in Italy in 1944–45
- Volta Redonda — Brazil's US-financed steel plant, a symbol of the economic side of hemispheric cooperation
- U-boat attacks (1942) — the trigger that finally pushed Brazil from neutrality into declaring war
Compare, don't just describe: A strong Paper 3 answer compares the US and Brazil directly: both moved from neutrality to full combat involvement, but the US was pushed in by a direct attack on its own territory (Pearl Harbor), while Brazil was pushed in by attacks on its shipping plus years of US diplomatic groundwork under the Good Neighbor policy.