Which 1916 battle did J.R.R. Tolkien experience during his military service in World War I?

J.R.R. Tolkien experienced the Battle of the Somme during his military service in World War I.

Tolkien served as a second lieutenant in the Lancashire Fusiliers and went to France in 1916. He participated in the Somme offensive, one of the largest and bloodiest campaigns of the First World War. The battle began on July 1, 1916, and continued until November.

Tolkien later became ill with trench fever and was sent back to England. Most of the officers in his battalion were killed, an experience that deeply affected him. His wartime memories are often discussed alongside themes of loss, endurance, friendship, and the destruction of landscapes in his fiction.

The Battle of the Somme did not directly provide a one-to-one model for a particular Middle-earth battle. Tolkien generally resisted simple claims that his stories were allegories of modern wars, although his experiences clearly informed aspects of his imagination.