By 1908, Isabel's eldest son Pedro wanted to marry an Austro-Hungarian aristocrat Countess Elisabeth Dobržensky de Dobrženicz, but Gaston and Isabel withheld consent because Elisabeth was not a princess. Their consent was only forthcoming when their second son, Luiz, who had travelled to Brazil but had been forbidden to land by the authorities, married Princess Maria Pia of Bourbon-Naples and Pedro renounced his claim to the Brazilian throne in favor of his brother. Luiz and his youngest brother Antônio both served in the British army during World War I (as members of the French royal family they were forbidden to serve in the French military). Luiz was invalided from active service in 1915, and Antônio died from wounds sustained in an air crash shortly after the armistice. Isabel wrote to Gaston that she "went out of mind" with grief "but the Good Lord restored it." Just three months later, Luiz died after a long illness. Isabel's own health was deteriorating, and by 1921 she was barely able to walk. She was too ill to travel to Brazil when the republican government lifted the family's banishment in 1920. Gaston and Pedro revisited Brazil in early 1921, for the reburial of Isabel's parents in Petrópolis Cathedral. Isabel died before the end of the year, and was buried in her husband's family tomb at Dreux's chapel royal. Gaston died the following year. In 1953, the remains of Gaston and Isabel were repatriated to Brazil, and in 1971 they were interred in the Cathedral of Petrópolis.