Representations of conflict in the early twentieth century respond both to the impact of mass industrial warfare, particularly in the First World War, and the development of mass culture following the Education Acts of the late nineteenth century. Concomitant with the development of literary modernism, the need to represent radically new forms of physical and mental experience reshaped war writing; a hundred years later, that influence persists. This chapter argues that war writing must be understood not simply as a response to individual conflicts; rather, the memory, expectation, and fear of war was a pervasive presence that continually shaped much of the period’s writing even in times of apparent peace, and supported a lucrative literary market in jingoistic literature, popular invasion fiction, and memoirs of wartime trauma. This chapter traces the lasting influence of the period’s major conflicts on its literary writing – particularly its prose – and concludes with a discussion of several post-war texts, published in the immediate aftermath of the First World War, which point towards the disenchanted and often angry tone of the 1928–30 War Books Boom.