Leon Blum was born in Paris, France, on 9th April, 1872. The son of Jewish parents, he studied law at the Sorbonne where he was converted to socialism.
After leaving university Blum worked for Jean Jaures. Rejected for military service by the French Army in the First World War, he entered the Chamber of Deputies in 1919. Blum became leader of the Socialist Party and in 1924 supported the government of Edouard Herriot.
Concerned by the emergence of Adolf Hitler in Nazi Germany, a group of left-wing politicians, led by Blum, Edouard Daladier, Maurice Thorez, Edouard Herriot, Daniel Mayer formed the Popular Front in November 1935. Parties involved in the agreement included the Communist Party, the Socialist Party and the Radical Party.
The parties involved in the Popular Front did well in the May 1936 parliamentary elections and won a total of 376 seats. Blum, leader of the Socialist Party, now become prime minister of France. Blum therefore became the first Jew in France history to hold this post.
Once in power the Popular Front government introduced the 40 hour week and other social reforms. It also nationalized the Bank of France and the armaments industry.
In July, 1936, José Giral, the prime minister of the Popular Front government in Spain, requested aid against the military uprising led by Emilio Mola, Francisco Franco and José Sanjurjo. Blum agreed to send aircraft and artillery. However, after coming under pressure from Stanley Baldwin and Anthony Eden in Britain, and more right-wing members of his own cabinet, he changed his mind. Blum now called for all countries in Europe not to intervene in the Spanish Civil War.
The Communist Party, that up to then had supported the Popular Front government, now organized large demonstrations against Blum's policy of non-intervention. With the left-wing in open revolt against the government and a growing economic crisis, Blum decided to resign on 22nd June.
Once in opposition Blum campaigned for France to end its nonintervention policy. On 13th March 1938 Blum returned to power as prime minister. He immediately reopened the frontier with Spain to allow vast amounts of military equipment to enter the country. Blum now came under considerable pressure from the right-wing press and political figures such as Henri-Philippe Petain and Maurice Gamelin. On 10th April 1938, Blum's government fell and he was replaced by Edouard Daladier as prime minister.
When the German Army invaded France in May 1940, Blum escaped to southern France but Henri-Philippe Petain ordered his arrest. Along with Edouard Daladier and Paul Reynaud he was tried in February, 1942, for betraying his country. He was handed over to the Germans who held him prisoner until 1945. Leon Blum died on 30th March, 1950.