On 14 April 1931, republican forces under the leadership of Alcala Zamora overthrew King Alfonso XIII of Spain and set up a provisional government. In the following four years, the republican government quelled three rebellions by Spanish military officers. The election on 16 February 1936 established a leftist coalition government. Manuel Azaña, a Marxist, succeeded Zamora as the president of Spain on 10 April 1936.
On 18 July 1936, General Francisco Franco led a military revolt against the new socialist regime. Within weeks, a civil war broke out between Franco's forces and the government. The war would last until 27 February 1939, when France and Britain recognized General Franco's fascist government.
During the conflict, the Soviet Union supported the republican forces with military equipment and training, while Nazi Germany and Fascist Italy sent troops and equipment to assist Franco's army. The Spanish Civil War gave the Soviet Union, Germany, and Italy the opportunity to test new aircraft and armoured vehicles and thus provided a preview of the weapons and tactics that would be used in the Second World War. Although the Canadian government did not actively support either side in the Spanish Civil War, 1,135 Canadians served as volunteers in the Republican International Brigades.