Used by the Spanish Republicans in the Spanish Civil War of 1931-1939, “Himno de Riego”, written during the 19th century, had been a popular patriotic song since it was written, including at the outbreak of the war. The anthem was named after Rafael de Riego, a general during the first period of republican rule (1820-1823). The anthem was also used briefly at the conclusion of that war (from April 7, 1822 to the 1823 restoration of the monarchy.)
The anthem was subsequently banned by Franco, who led the campaign against the republican forces in the civil war and who led the country following the defeat of the Republicans.
Special thanks to: Reinhard Popp and Francesc A.Roca for some of this information.