What was the name of C.S. Lewis’s brother, Warren?

C.S. Lewis’s brother was Warren Hamilton Lewis. Warren, often called Warnie, was born in 1895 and was three years older than his famous younger brother.

The brothers shared a lifelong relationship shaped by reading, family changes, military service, and domestic life. Warren served in the British Army during the First World War and later became a historian. His journals and historical writing provide important evidence about C.S. Lewis’s daily life and friendships.

Warren also lived with Lewis for many years at The Kilns near Oxford. He helped manage practical matters in the household and preserved extensive records. His diaries are among the most useful primary sources for biographers studying Lewis outside his published work.

The brothers’ relationship appears in accounts of Lewis’s childhood and adulthood, but Warren was not the literary collaborator behind Lewis’s books. C.S. Lewis wrote the published works himself, while Warren’s importance lies especially in his companionship, military career, historical scholarship, and firsthand documentation.