After World War II began, Germany invaded and occupied northwestern France beginning in May 1940. The Americans entered the war in December 1941, and by 1942 they and the British (who had been evacuated from the beaches of Dunkirk in May 1940 after being cut off by the Germans in the Battle of France) were considering the possibility of a major Allied invasion across the English Channel.

The following year, Allied plans for a cross-Channel invasion began to ramp up. In November 1943, Adolf Hitler (1889-1945), who was aware of the threat of an invasion along France’s northern coast, put Erwin Rommel (1891-1944) in charge of spearheading defense operations in the region, even though the Germans did not know exactly where the Allies would strike. Hitler charged Rommel with finishing the Atlantic Wall, a 2,400-mile fortification of bunkers, landmines and beach and water obstacles.

In January 1944, General Dwight Eisenhower (1890-1969) was appointed commander of Operation Overlord. In the months and weeks before D-Day, the Allies carried out a massive deception operation intended to make the Germans think the main invasion target was Pas-de-Calais (the narrowest point between Britain and France) rather than Normandy. In addition, they led the Germans to believe that Norway and other locations were also potential invasion targets. Many tactics were used to carry out the deception, including fake equipment; a phantom army commanded by George Patton and supposedly based in England, across from Pas-de-Calais; double agents; and fraudulent radio transmissions.

Eisenhower selected June 5, 1944, as the date for the invasion; however, bad weather on the days leading up to the operation caused it to be delayed for 24 hours. On the morning of June 5, after his meteorologist predicted improved conditions for the following day, Eisenhower gave the go-ahead for Operation Overlord. He told the troops: “You are about to embark upon the Great Crusade, toward which we have striven these many months. The eyes of the world are upon you.”

Later that day, more than 5,000 ships and landing craft carrying troops and supplies left England for the trip across the Channel to France, while more than 11,000 aircraft were mobilized to provide air cover and support for the invasion.

By dawn on June 6, thousands of paratroopers and glider troops were already on the ground behind enemy lines, securing bridges and exit roads. The amphibious invasions began at 6:30 a.m. The British and Canadians overcame light opposition to capture beaches codenamed Gold, Juno and Sword, as did the Americans at Utah Beach. U.S. forces faced heavy resistance at Omaha Beach, where there were over 2,000 American casualties. However, by day’s end, approximately 156,000 Allied troops had successfully stormed Normandy’s beaches. According to some estimates, more than 4,000 Allied troops lost their lives in the D-Day invasion, with thousands more wounded or missing.

Less than a week later, on June 11, the beaches were fully secured and over 326,000 troops, more than 50,000 vehicles and some 100,000 tons of equipment had landed at Normandy.

For their part, the Germans suffered from confusion in the ranks and the absence of celebrated commander Rommel, who was away on leave. At first, Hitler, believing the invasion was a feint designed to distract the Germans from a coming attack north of the Seine River, refused to release nearby divisions to join the counterattack. Reinforcements had to be called from further afield, causing delays. He also hesitated in calling for armored divisions to help in the defense. Moreover, the Germans were hampered by effective Allied air support, which took out many key bridges and forced the Germans to take long detours, as well as efficient Allied naval support, which helped protect advancing Allied troops.

In the ensuing weeks, the Allies fought their way across the Normandy countryside in the face of determined German resistance, as well as a dense landscape of marshes and hedgerows. By the end of June, the Allies had seized the vital port of Cherbourg, landed approximately 850,000 men and 150,000 vehicles in Normandy, and were poised to continue their march across France.

By the end of August 1944, the Allies had reached the Seine River, Paris was liberated and the Germans had been removed from northwestern France, effectively concluding the Battle of Normandy. The Allied forces then prepared to enter Germany, where they would meet up with Soviet troops moving in from the east.

The Normandy invasion began to turn the tide against the Nazis. A significant psychological blow, it also prevented Hitler from sending troops from France to build up his Eastern Front against the advancing Soviets. The following spring, on May 8, 1945, the Allies formally accepted the unconditional surrender of Nazi Germany. Hitler had committed suicide a week earlier, on April 30.