D-Day is the second book in the "History at a Glance" series that began with Michael Varhola's Fire Ice: The Korean War, 1950-1953 and was written to provide an overview of the subject for people with little or no knowledge of the invasion. Yet, it also serves as a useful road map for experienced students of World War II who want to discover other avenues worthy of deeper investigation. An online companion to this book is available where readers can leave comments, correspond with the authors, and find interviews, errata, articles, and other useful features and information.