The Treaty of Versailles had created the League of Nations, an organization of mostly European nations but also Ethiopia, Japan, Siam, and many Latin American states. The United States, which had reverted to an isolationist foreign policy, never joined. The League did have some successes in demonstrating the power of institutional cooperation between nations, notably with combating malaria and other diseases in Europe, stopping labor abuses, controlling the distribution of opium products, and lessening the slave trade in Africa and Asia. However, the League never succeeded with its primary purpose, that of stopping large-scale international conflicts. Dominated by Britain and France, the League promoted voluntary cooperation and anti-war policies like trade sanctions, rather than creating a global police force. In the 1930s, the League failed to react effectively to the actions of totalitarian regimes: the Japanese invasion of Manchuria, the Italian conquest of Ethiopia, and the German militarization of the Rhineland. The League’s final failure was its paralysis during the drawn-out civil war in Spain.
Spain had a growing urban population and a poor countryside dominated by wealthy families and the Catholic Church. In 1932, the king abdicated and a republic was formed which introduced liberal reforms such as universal non-religious education, equality for women, and redistribution of farmland to the peasants. Conservative reaction and increasing social discord reached a climax in 1936, when right-wing army officers revolted, led by General Francisco Franco. The resulting civil war lasted for three years. The conflict has been called a “dress rehearsal” for the Second World War for two reasons. First, Spanish democracy and liberalism stood in between two extremes: the fascist-backed forces of Franco and the communist-dominated forces supporting the left-wing Republic. The idea of a moderate center holding firm against totalitarianism on the left and right seemed doomed. Second, the war was fought with the active participation of foreign volunteers and soldiers, especially from Fascist Italy and Nazi Germany. These powers tested new weapons and tactics that would prove effective on the global battlefronts a few years later. The most famous example of this was Germany’s air raid on the undefended town of Guernica, in response to which the painter Pablo Picasso produced one of the twentieth century’s most famous paintings, Guernica. This work of modern art stands as a continual reminder of civilian suffering in the midst of war. Franco defeated the Republican forces in 1939, but Fascist Spain, shattered by the war, played little part in the Second World War that broke out a few months later.
Hitler followed his reoccupation of the Rhineland with further claims to German-inhabited territories in Eastern Europe. Traditional Great Power politics, which Wilson had hoped to end with the League, returned in force. Britain and France’s policy of appeasement (trying to distinguish reasonable from unreasonable demands) allowed Germany to annex Austria, which the Versailles treaty had forbidden. In the 1938 Munich Agreement, against Czech protests, Hitler was given the Sudetenland, a German-speaking area in western Czechoslovakia. In exchange, Hitler pledged to make no more territorial demands. However, he invaded and annexed the rest of the country the next spring. With the failure of appeasement, Britain and France reluctantly guaranteed the security of Hitler’s next victim, Poland, which separated eastern Prussia from the rest of Germany. The Western allies counted on the Soviet Union to oppose this German threat to its border. However, Hitler and Stalin overcame their ideological differences with a joint agreement to invade Poland in September 1939. Britain and France declared war, and fighting soon consumed the continent, just twenty-five years after the first World War began. In both cases, the immediate cause was German ambition to dominate eastern Europe.