The document summarizes planning for the D-Day invasion of Normandy on June 6, 1944. It describes how Allied forces were concerned about heavy casualties due to the strength of German defenses. The invasion involved elaborate planning including rehearsals and deception tactics. On D-Day, thousands of Allied troops landed along the Normandy coast after airborne units were dropped behind enemy lines and bombers softened up German positions, although the airborne landings encountered difficulties. The massive amphibious invasion was the largest such operation in history.