J.R.R. Tolkien served in World War I as a second lieutenant in the Lancashire Fusiliers.
Tolkien was commissioned in the British Army in 1915 after studying at Oxford. He served with the 11th Service Battalion, Lancashire Fusiliers, and went to France in June 1916. His battalion took part in the Battle of the Somme, one of the most costly campaigns of the war.
Tolkien became ill with trench fever and was sent back to England in October 1916. The illness prevented his return to active service, and he spent much of the remaining war period recovering or performing duties in England.
Readers sometimes connect particular Middle-earth characters directly to individual wartime friends, but Tolkien generally resisted simple one-to-one interpretations. His wartime experiences nevertheless formed an important part of the historical background of his generation and influenced the atmosphere of his writing.