Under Fire: The Story of a Squad (French: Le Feu: journal d'une escouade) is a 1916 war novel written by French novelist Henri Barbusse. Even though the story is purely fictional, it is in fact based on Barbusse’s personal experiences as a soldier on the Western front in the First World War. Because of its militaristic and socialistic themes, the novel is considered the first book to be written about World War I.

Under Fire was originally published in French, and it received mixed reviews; some critics described it as a war masterpiece while others called it Barbusse’s unnecessary attempt to fictionalize the First World War. Perhaps the novel's controversial narrative was what attracted readers, and its popularity lead to the book's first English translation and publication in 1917. The novel was also praised by many readers for its extremely realistic depictions of war, battle, survival, death, and camaraderie.

Barbusse claimed that he wrote the novel while on active duty in the French Sixth Battalion. He took notes while serving and later reviewed and compiled them after he was injured on the front. Thus, the story is written in the form of a journal or a personal diary. Barbusse presents several episodic anecdotes which (for the most part) constitute the novel’s chapters. Arguably, the most famous chapter is titled "The Fire," which describes a battle between the Allied forces and the German soldiers in No-Man’s land when the French attacked the German trench.

In his novel, Barbusse tends to give special meaning to small moments and scenes—such as a young woman passing by or a soldier drawing his weapon—describing them in great detail. Thus, Under Fire has often been compared to similar literary classics that depict war-time conditions (e.g., A Farewell to Arms (1929) by Ernest Hemingway and All Quiet on the Western Front (1929) by Erich Maria Remarque).

Essentially, with Under Fire, Barbusse manages to capture many of the Allied experiences in the First World War, and unintentionally provides some theoretical explanations on how World War I may have lead into World War II. Thus, his last chapter foreshadows the totalitarian and cruel regime that will come several years later.