D-Day, June 6, 1944, opens this account of Operation Overlord, the largest amphibious invasion ever attempted and the operation that broke Germany's grip on Western Europe. The film works backward from the beaches to the planning rooms, laying out Operation Bodyguard's deception campaign that convinced German command the real landing would fall elsewhere, and the engineering behind 'Hobart's Funnies', the modified tanks built to clear mines and obstacles under fire. It examines the Mulberry Harbors, the artificial ports towed across the Channel to supply troops without a captured port, and sets Eisenhower's coordination of the Allied command against Rommel's Atlantic Wall defenses. Archival footage and maps trace the assault beach by beach, from the cliffs above Omaha to the causeways behind Utah, with the strategic decisions on both sides given equal weight. The result is a chronological, briefing-style account of how the invasion was conceived, disguised, and executed, aimed at viewers who want the mechanics behind the famous images rather than just the images themselves.