On June 6, 1944, more than 6,000 Allied ships carried more than a million soldiers across the English Channel to the Normandy coast in German-occupied France, carrying out the greatest sea-borne assault in history. As Craig Symonds explains, however, D-Day was also the culmination of Operation Neptune, a three-year project occasioning intense debate between a cautious Winston Churchill and U.S. Army Chief of Staff General George C. Marshall, who wanted to invade as soon as possible. Adding perspective to this world-changing event, Symonds discusses the strategies, the logistical challenges, and above all, the soldiers and statesmen who made D-Day possible.