The Spanish Civil War (1936–1939) was a brutal conflict between the leftist Republicans and the right-wing Nationalists led by General Francisco Franco. It is often described as a 'dress rehearsal' for World War II because it became a battleground for competing ideologies and new military technologies. Nazi Germany and Fascist Italy provided massive support to Franco, using the conflict to test new weapons like the Messerschmitt Bf 109 fighter and the Junkers Ju 87 'Stuka' dive bomber. The infamous bombing of the town of Guernica by the German Condor Legion demonstrated the terrifying potential of aerial terror bombing against civilian populations. Meanwhile, the Soviet Union and international volunteers (the International Brigades) supported the Republicans. Franco’s victory established a long-lasting dictatorship and cemented the alliance between Hitler and Mussolini.