After defeating Poland in September 1939, German forces sweep through the Netherlands and Belgium, heading for France. The heavily fortified Maginot Line protects France’s borders, but German General Erich von Manstein spots a weak point in the Ardennes Forest—and exploits it to shocking effect.

Winston Churchill, called upon to lead Britain after Neville Chamberlain resigns, begins his premiership in one of the most catastrophic weeks in British history. Allied forces in France are quickly overwhelmed, retreating in full to the coast. With British forces trapped in a corner, Churchill is pressured to consider a negotiation with Adolf Hitler as they struggle to get their surviving troops back home. Answering a desperate call, volunteer vessels come to the rescue of the stranded troops under attack at Dunkirk.

France quickly signs an armistice with Nazi Germany, and the United States looks on in shock while Hitler’s victory parade marches through the streets of Paris. Franklin Roosevelt calls to mobilize US wartime production as London defends her skies from German bombers.

But Hitler is forced to call off his invasion plan for the British Isle, thanks to Britain’s heroic Royal Air Force (RAF). After being elected for a third term, Roosevelt declares the United States’s role as the arsenal of democracy, supporting Britain as she stands—now alone—against Hitler.