During the Spanich Civil War, the Republican-held Spanish city of Guernica was bombed by planes of the German Luftwaffe’s Condor Legion on 26 April 1937. Hundreds of civilians were killed and the city was almost complete destroyed. The attack showed the effectiveness of the terror bombing to Hermann Göring and other Nazi commanders.
This event inspired the painting 'Guernica' by Pablo Picasso, which was displayed at the International Exposition of Art and Technology in Modern Life later that year in Paris.