The Nationalist side conducted aerial bombing of cities in Republican territory, carried out mainly by the Luftwaffe volunteers of the Condor Legion and the Italian air force volunteers of the Corpo Truppe Volontarie: Madrid, Barcelona, Valencia, Guernica, Durango, and other cities were attacked. The Bombing of Guernica was the most controversial. The Italian air force conducted a particularly heavy bombing raid on Barcelona in early 1938. While some Nationalist leaders did oppose the bombing of the city – for example, Generals Yagüe and Moscardó, who were noted for being nonconformists, protested against the indiscriminate destruction – other Nationalist leaders, often those of a fascist persuasion, approved of the bombings which they saw as necessary to "cleanse" Barcelona.