Twenty-four-year-old J. R. R. Tolkien, a second lieutenant in the British Expeditionary Force, was among their number—an experience that would shape the course of his life and literary career. Tolkien spent nearly four months in the trenches of the Somme valley, often under intense enemy fire. As he recalled years later: "One has indeed personally to come under the shadow of war to feel its full oppression." A hundred years hence and the Somme offensive still casts its oppressive shadow across the landscape of the West. It symbolizes not only the human tragedy of an ill-conceived war but the fearsome cost of a mistaken idea: the notion of human perfectibility.