The isolated area of Vizcaya, a predominantly Basque part of northern Spain, was the most immediate target, in what was called the War in the North. It was largely a Nationalist and Italian offensive, but was supported by a consistently re-equipping Condor Legion. The terrain was favourable, with the planes coming over a range of mountains to the south, masking their entrance. Sperrle remained in Salamanca; Wolfram von Richthofen replaced Holle in January as deputy and in actual command. Since the Basque air force was very limited, even fighters were used in ground-attack roles. The Legion's air force initially attacked the towns of Ochandiano and Durango. Durango had no anti-aircraft defence, and only minor other defences. According to the Basques, 250 civilians died on the 31 March, including the priest, nuns and congregation of a church ceremony. The Germans, with their air raids, were hated. The Basque ground forces were in full retreat towards Bilbao, through the town of Guernica, which was attacked on 26 April in one of the most controversial attacks of the Spanish Civil War.