Léon Daudet (1867-1942) was a writer and political activist who produced a number of science fiction novels. Translations of the two most significant were published in 2013 by Brian Stableford: The Napus: The Great Plague of the Year 2227 (1927) and The Bacchantes: A Dionysian Scientific Romance (1931).
Le Napus is about a plague, apparently designed deliberately to wipe out humanity; Stableford calls it “one of the classics of absurdist science fiction”. Les Bacchantes is about the struggle of a scientist to develop a technology to capture and control the “waves of time”, to allow echoes of the past to be brought forward into clearer focus. The publisher’s blurb (probably written by Stableford) says “After being temporarily blinded by a jealous rival in love, he feels impelled to celebrate the restoration of his sight by means of a historical re-enactment of s series of frescoes found in the recently-excavated Villa of the Mysteries in Pompeii, aided and facilitated by his wave-enhancing apparatus, the Dyonisos. The result testifies to the subtle force of the waves of time, both in history and on the contemporary human psyche. A strikingly original—and erotic—SF novel about the nature of time!”
Daudet also published a Swiftian satire, Les Morticoles (1894); and Ciel de feu (1934), which imagined a future war between France and Germany: “it does not add much to the theme of imaginary war,” comments Versins.
Daudet was the son of Alphonse Daudet, the much-loved author of Lettres de mon moulin (1870) and Tartarin de Tarascon. He was born and brought up in Paris, and as a child he met most of the great writers of France (Flaubert, Maupassant, Zola). One of his school-friends was Marcel Proust. In 1891 he married the grand-daughter of Victor Hugo. His father had brought him up to be a left-wing republican, and that was also the political world of his wife. But Daudet turned away from that: he espoused anti-Semitism, and became a violent opponent of Dreyfus. In 1894 his wife left him, and they divorced. In 1904 he met the duke of Orleans, and soon became a monarchist. He was one of the founders of the daily paper L’Action française in 1908 and became its editor. His War Experiences consisted of editing the paper and uncovering what he believed to be German conspiracies.
After the war, from 1919 to 1924, he was the principal spokesman in parliament for the right-wing nationalists. In 1923 his 14-year-old son Philippe left home, and, after trying to go to Canada, was found dead in a taxi in Paris. (There is a separate Wikipédia page on the Philippe Daudet affair.) A letter from Philippe to his mother announced that he was going to commit suicide. Daudet maintained that it was murder, and not suicide. He accused a police officer of complicity and of lying, and was sued for defamation. He was sentenced in 1925 to five months in prison. However, he was sprung from jail by some friends, and went into exile in Belgium.
During his two years in Brussels he continued to write and to engage in politics. He renounced his anti-semitism, saying that democracy was his enemy, not the Jew. When he returned to Paris he continued to play an active role in politics. He supported Marshal Pétain’s Vichy government; and died in Saint-Rémy-de-Provence, not far from the mill that featured in his father’s Lettres de mon moulin.
My information comes so far almost exclusively from Wikipédia, together with the entry in Pierre Versins’ Encyclopédie de l’utopie, etc, 224.