"The Longest Day" is a non-fiction book by Cornelius Ryan that tells the story of the Normandy landings during World War II, also known as D-Day. The book covers the planning, preparation, and execution of the Allied invasion of German-occupied France on June 6, 1944, which marked a turning point in the war. Ryan draws on extensive research, including interviews with participants on both sides of the conflict, to provide a vivid and detailed account of the military strategy, tactics, and logistics involved in the operation. He also explores the personal experiences and perspectives of individual soldiers, officers, and civilians caught up in the chaos of the battle. Through his compelling narrative, Ryan conveys the scale, complexity, and human cost of one of the most significant events in modern history, and pays tribute to the courage and sacrifice of the men and women who fought and died for freedom.