Despite the early success on D-Day, the Allies made little progress in the weeks that followed, bottled up around their beachheads and unable to push past the Germans blocking their path. The British had planned on taking Caen on D-Day, opening the road to Paris, but German panzer reserves delayed the forces of Field Marshall Bernard Montgomery for more than a month.

The Americans also remained bogged down in Normandy. For weeks, they tangled with German forces in the bocage, a patchwork of farm fields and orchards separated by dense, 20-foot-high hedgerows that concealed enemy snipers, machine-gun nests, and even tanks. It was a grueling, back-and-forth affair, with the two sides battling for mere yards each day across the blood-soaked ground.

A breakthrough finally came in late July when the town of Saint-Lô, a German strongpoint and critical road juncture, fell to US forces. A carpet bombing operation followed, obliterating large swaths of German armor and infantry and shattering their defensive line.

While fresh Allied divisions continued to arrive in Normandy, the German leader, Field Marshal Erwin Rommel, had few reinforcements, and Adolf Hitler refused to allow any strategic retreat. He ordered futile counterattacks instead that led to mass encirclements of his own troops and hastened the German collapse. General George Patton’s US Third Army rolled into action, and by August, the Allies were charging toward Paris.

A second front was also opened in the south of France, where an Allied force led by the US Seventh Army arrived and captured the key ports of Marseilles and Toulon. Enraged by the Allied advance, a fuming Hitler ordered Paris destroyed by artillery, but the German commandant in the city ignored the missive and surrendered his garrison. With their defensive lines unable to hold, the Germans began a frenzied retreat to their own soil and the still-occupied Low Countries. By September, most of France had been liberated.