Complex sentence: During the Spanish Civil War, he was one of the main promoters of the Basque Country national football team, which played in Europe and the Americas to raise funds for Basque refugee children whose parents had been forced into exile.
Split into simpler sentences: During the Spanish Civil War, he was one of the main promoters of the Basque Country national football team. This regional team played in Europe and America to raise funds for the Basque refugee children whose parents had been forced to escape into exile.