After living in Marseille, the family briefly moved to Morocco, but then returned to Spain because Mr. Almudéver’s mother fell seriously ill in 1931, just as the Republican government was taking office.
Mr. Almudéver was detained by Franco’s troops in Valencia in 1939, just as Franco was about to win the war, and was held in work camps and prisons until his release in 1942. Determined to continue the struggle against Franco’s new regime, he then joined an underground Communist labor union that was also helping guerrilla fighters in northeastern Spain. In 1947, after some fighters were caught and executed, he fled on foot across the Pyrenees mountains to the French town of Pamiers, where a brother lived. A year later his wife, Carmen Ballester Vicens, managed to join him in France.
Almudena Cros, the president of the Association of Friends of the International Brigades, which was set up in Madrid in the 1980s, said that she was “99 percent sure” that Mr. Almudéver was “the last man standing” and there was no other surviving member of the Brigades.
She said that he had contributed greatly to promoting the historical importance of the Brigades, not least because he remained “so sharp, forceful and clear” when recalling his wartime experience. “He loved whenever he could visit schools and speak to young people about the lesser known aspects of our own Spanish history,” she said.
Pedro Sánchez, Spain’s prime minister, said on Twitter that Mr. Almudéver stood out because of his “political engagement and perseverance,” noting that he had not only fought for democracy and against dictatorship but also then suffered “postwar repression and exile.” Ximo Puig, the regional leader of Valencia, also paid tribute on Twitter to Mr. Almudéver for “fighting for the democratic convictions of all his people.”
Like his father, Mr. Almudéver worked in the construction industry, while devoting much of his spare time to keeping alive the memory of the civil war, his daughter Sonia said. In 2014, Mr. Almudéver published an autobiography, called “The Pact of Nonintervention, Poor Republic.” In 2016, he joined Ms. Cros and her association on a tour of Spain to mark the 80th anniversary of the creation of the Brigades.