On May 19, 1937, Republican Spain was divided into eight Air Regions, replacing the former Escuadra system of organization: Madrid, Guadalajara, and Cuenca; Murcia, from Hellin to Almeria; Catalonia and eastern Aragon; Valencia, including Alicante; Ciudad Real, and parts of Estremadura; the Basque-Asturian enclave; Albacete and La Mancha; and Jaen and eastern Andalusia. The Air Regions corresponded to the construction and upkeep of more than 400 Soviet-built airfields in the Government zone during 1937, most being camouflaged rural homesteads, abandoned estates, or forests. Republican squadrons were later moved from field to field, often on a daily basis, to minimize the threat of suprise attack. The former Escuadra now represented an organizational entity, instead of a geographical unit, closely resembling the interwar "Commands" of the Royal Air Force.
There also occurred significant changes among Loyalist first-line combat pilots. A sprinkling of Spanish and American flyers joined Grupo 21's formerly all-Russian Mosca escuadrillas in the early summer of 1937; and the number of Spanish I-16 pilots dramatically rose thereafter. Among Grupo 26's four Chato squadrons, the Escuadrilla LaCalle was reformed with Spanish pilots and dispatched to the Basque zone, following LaCalle's departure tot he USSR as head of the 2nd Promocin (training course). The 1st Chato Escuadrilla remained largely Russian until May 1938; the other I-15 escuadrillas being mainly or entirely Spanish from May 1937, onwards. The Government air war had become, little by little, a truly Spanish affair.
There also occurred significant changes among Loyalist first-line combat pilots. A sprinkling of Spanish and American flyers joined Grupo 21's formerly all-Russian Mosca escuadrillas in the early summer of 1937; and the number of Spanish I-16 pilots dramatically rose thereafter. Among Grupo 26's four Chato squadrons, the Escuadrilla LaCalle was reformed with Spanish pilots and dispatched to the Basque zone, following LaCalle's departure tot he USSR as head of the 2nd Promocin (training course). The 1st Chato Escuadrilla remained largely Russian until May 1938; the other I-15 escuadrillas being mainly or entirely Spanish from May 1937, onwards. The Government air war had become, little by little, a truly Spanish affair.