José Moreno

When José Moreno was captured in 1937 during the Spanish Civil War, he was sentenced to death by one of the commanders in Franco's army.

For reasons he says he never understood, he was spared that fate. He celebrated his 100th birthday in November.

“I should have died then — but here I am, feeling well enough to remember clearly all that I’ve endured,” said Mr. Moreno, with a big grin. “I still don’t really know why I wasn’t killed and instead sent to prison, so it’s very hard to believe that I have managed to live so long.”

Mr. Moreno was only a teenager when the civil war started, but it is a chapter of his life that he has not tried — or perhaps managed — to close.

While he watches the news in color these days, his views remain black and white, shaped by his wartime experience and his ardent support for Basque nationalism.

His latest concern is the resurgence of the far right. In December, Vox, a nationalist, anti-immigrant party, won its first parliamentary seats in an election in the southern region of Andalusia.

Mr. Moreno now shares an apartment with his daughter, Manuela, in the Bilbao suburb of Portugalete, close to the shipyards where he once worked. The apartment is filled with Basque memorabilia, including photos of Mr. Moreno meeting local politicians.