The Normandy campaign in the summer of 1944 was perhaps the most important battle of the twentieth century. It decided the fate of Nazi Germany. This historiographical narrative critically assesses the important literature on the campaign and offers the most comprehensive bibliography on the subject to date. This research guide is easily accessible, with cross-references between the text and the bibliography and a full index. It has been developed for use in public, college, university, and institutional libraries and to serve military historians and history buffs interested in D-Day. The narrative provides a brief historical background, describes ten different types of sources for conducting research on the Normandy campaign and then looks at sources concerned with the Second Front, Overlord, air and naval preparations, Operation Fortitude, D-Day, and the Battle for Normandy, before pointing to trends and future research needs. The second part of the book lists 539 works on the Normandy campaign, including references, bibliographies, guides, dissertations, books, documents, and magazine articles. The emphasis is on English-language works, but the most significant French and German materials are included also.