The horrors of the First World War had a deep impact on literature both in terms of themes and literary techniques. Writers on both sides of the Atlantic remarked that the old world had finished with the war and the twenties ushered in a new order, both in social and literary terms. "It was in 1915 the old world ended," stated D. H. Lawrence while Willa Cather famously observed that "the world broke in two in 1922 or thereabouts". In literature this meant a shift from realism to modernism. While several realist writers had already paid attention to characters' psychology (see, for example, Henry James's Portrait of a Lady with its strong focalization through Isabel's eyes), modernist writers took this to the extreme claiming that what counted was not reality per se but how characters perceived it. In addition, modernism embodied the fragmentation and the loss of certainties of the post-war world with radical narrative techniques that challenged linear chronological development and tried to reproduce the flux of the characters' thoughts (the so-called stream of consciousness).

Technology and urban life which had been important themes in realist fiction continued to fascinate modernist writers who also investigated the impact of the war on the characters' lives and on social conventions (see, for example, Hemingway's The Sun Also Rises).