Top Secret Maps Reveal The Massive Allied Effort Behind D-Day

As dawn broke on June 6, 1944, in northern France, the Allies began an invasion in the works for years: D-Day, the start of Operation Overlord that turned the tide against Nazi Germany.

THE ALLIED INVASION of German-occupied France that began in the early hours of June 6, 1944, was long in the making. By gaining supremacy in the Atlantic in 1943, the Allies had cleared the way for a huge buildup of American troops and equipment in Great Britain. Between January and June 1944, nine million tons of supplies and 800,000 soldiers crossed the Atlantic from the United States to bolster the invasion, designated Operation Overlord.

 

THE COMMANDERS


First Lt. Wallace C. Strobel and the paratroopers of the U.S. 101st Airborne Division listen to General Eisenhower before the departure for Normandy.
PHOTOGRAPH BY JOHN PARROT/STOCKTREK/ALBUM


The Allies' meticulous plans to invade Normandy in 1944 were overseen by Dwight D. Eisenhower, appointed supreme commander in Europe the year before. In addition to a formidable military record, the future 34th president of the United States inspired his troops with his warmth and rousing addresses. Second in command was Britain’s Field Marshal Bernard Law Montgomery, who defeated German forces, under the command of Erwin Rommel, in North Africa, a major turning point of the war. Hitler later entrusted Rommel with defense of France’s channel coast, where, as D-Day dawned, he and Montgomery once again faced one another as the war’s dramatic endgame began.

Left: British Field Marshal B.L. Montgomery pointing to Normandy in a 1945 painting by Frank O. Salisbury
Right: German field marshal Erwin Rommel inspecting the Atlantic defenses in France, in 1943 or 1944.
PHOTOGRAPH BY GRANGER/ALBUM (LEFT) AND PHOTOGRAPH BY AFP/GETTY IMAGES (RIGHT)

Meanwhile, Allied pilots exploited their hard-won superiority over the diminished German Luftwaffe by blasting French railways and bridges to keep their foes from rushing reserves to Normandy when troops landed there. Anglo-American commanders battle tested in North Africa and Italy, including American Dwight D. Eisenhower and Bernard Montgomery of the United Kingdom, prepared to lead invasion troops against their old foe, German general Erwin Rommel, assigned to strengthen French coastal defenses while the bulk of the German Army struggled to hold back resurgent Soviets on the Eastern Front. (See also: Memories of D-Day come alive on the beaches where it happened.)

A confidential folder of the type used for the Allied planning of Overlord.
PHOTOGRAPH BY KENNETH W. RENDELL, INTERNATIONAL MUSEUM OF WORLD WAR II

The German wall

Planning for Operation Overlord began in London more than a year before the invasion took place. Allied staff officers led by Lt. Gen. Frederick Morgan debated where to pierce the Atlantic Wall, German coastal fortifications extending from Norway to the southwest coast of France. The shortest route to Germany lay across the Strait of Dover (Pas-de-Calais), but landing around Calais meant attacking the strongest sector of the Atlantic Wall.

Morgan and staff decided instead to land on the coast of Normandy, which lay farther from Germany but was less heavily fortified. Their original plan, drawn up in strict secrecy, called for three divisions to come ashore on a narrow front on D-Day. But when Eisenhower and Montgomery arrived in London in early 1944 to serve respectively as supreme commander and field commander of the Allied Expeditionary Force destined for Normandy, they altered the invasion plan based on amphibious operations in Italy. (See also: Excerpt: Rare World War II maps reveal Japan's Pearl Harbor strategy.)

PIERCING THE WALL
The German defensive barrier known as the Atlantic Wall included two areas that met the requirements for a massive Allied invasion—beaches that were accessible to landing craft, tanks, and other vehicles and were not too far from British ports or from Germany, the ultimate objective. Suitable beaches around Calais were only 48 kilometres from the port of Dover and 322 kilometres from the German border, but their proximity to the Reich meant that they were well defended. The other promising landing site—between the fortified ports of Le Havre and Cherbourg in Normandy—was farther from Germany but was chosen because beaches there were less heavily defended.
MAP BY NG MAPS

Five divisions would land on D-Day on a broader front, supported by three airborne divisions and followed by an immense influx of men and material. The huge commitment of landing craft and other resources to Normandy meant that a second invasion of France along the Mediterranean coast, which was meant to coincide with Overlord to prevent Germans in the south from being shifted to Normandy, would instead take place a few months after Overlord unfolded.

Germany’s defense

German commanders did not ignore the potential threat to Normandy. Rommel—in charge of Army Group B under Field Marshal Gerd von Rundstedt, German commander in chief in the West—laced beaches there with mines as well as obstructions that would force landing craft to disgorge troops at low tide, leaving them more exposed to enemy fire. Rommel wanted panzer divisions deployed at likely landing sites in Normandy to repulse invaders before they established a beachhead and were reinforced. “Everything we have must be on the coast,” he insisted.

Rundstedt disagreed, and Hitler decided to hold most German armoured forces in reserve under his own control until the invasion took place. Only one panzer division guarded the Normandy coast beforehand. An elaborate Allied deception campaign called Operation Bodyguard—which included simulating phantom divisions and feeding false reports to Berlin from German agents under British control—led Hitler to view landings at Normandy as a diversion, which would be followed by a massive Allied thrust across the Strait of Dover.

DEFENDING THE COAST
Rommel (front row, third from left) inspecting a beach near Calais in April 1944, made sure that obstacles laid there were also installed on the Normandy coast. His request to defend that coast with armoured divisions to meet invaders head-on was denied.
PHOTOGRAPH BY PRISMA BY DUKAS PRESSEAGENTUR GMBH/ALAMY STOCK PHOTO

Dawning of D-Day

The invasion of Normandy was preceded by daring coastal and aerial reconnaissance that yielded detailed charts of the five landing zones: Gold, Juno, Sword, Utah, and Omaha beaches.

Omaha Beach, the largest of the of the D-Day attack zones, was subdivided into areas which were code-named Charlie, Dog (divided into Green, White, and Red sections), Easy (divided into Green and Red sections), and Fox (divided into Green and Red sections).

Ensign Joseph Vaghi, a beachmaster at Omaha Beach, carried this top secret map to show where troops and equipment would deploy along the coast.
PHOTOGRAPH BY COLLECTION OF JOE VAGHI

Foul weather forced Eisenhower to postpone Overlord until June 6. Two more weeks would pass before the moon and tides were again favourable for paratroopers landing inland before dawn and soldiers landing on the beaches at daybreak.

The decision to proceed on the sixth, during a predicted lull in the storm, caught German commanders by surprise. But some Allied landing craft and amphibious tanks sank in swells, and men who stayed afloat were seasick. Nausea mingled with dread as they disembarked under fire. “Many were hit in the water and drowned,” recalled Sgt. Bob Slaughter of the U.S. 29th Infantry Regiment. “There were dead men in the water and live men acting dead, letting the tide take them in.”

War photographer Robert Capa accompanied the first wave of troops as they faced enemy fire and captured some of the most searing images of D-Day.
PHOTOGRAPH BY ROBERT CAPA INTERNATIONAL CENTER OF PHOTOGRAPHY/MAGNUM PHOTOS/CONTACTO

Nearly 3,000 Americans were killed or wounded on Omaha Beach, most of them in the first few hours. As shellfire from Allied warships began silencing enemy gunners on the cliffs, however, soldiers rallied and pushed inland through ravines toward Colleville-sur-Mer. Americans who landed at Utah Beach faced little resistance, and British and Canadian troops advanced several miles inland from their beaches and withstood a late-day counterattack by the 21st Panzer Division.

A map of Utah Beach, based on aerial photos, was used to plan landings there.
MAP BY LIBRARY OF CONGRESS, CT002437A

When Rommel returned that night to Normandy—after celebrating his wife’s birthday during the storm he thought would preclude an invasion—his worst fears were realised. He had warned a fellow officer that their only chance was to stop the enemy in the water. Now nearly 160,000 Allied troops had landed.

Expanding the beachhead

Following D-Day, the Allies had to transport troops and supplies to Normandy in vast amounts without access to a deepwater port. Germans assumed that their foes would require such a port, which lent credence to Allied deceptions portraying the Normandy landings as a diversion, to be followed by a big push aimed at a deeper port like Calais.

OVERLORD AND BODYGUARD

Operation Overlord was shielded from the Germans by Operation Bodyguard, inspired by Churchill’s remark that truth in wartime should always be “attended by a bodyguard of lies.” That meant simulating preparations for landings elsewhere to keep German forces dispersed.
The tactical deceptions underpinning Bodyguard included dropping dummies by parachute, such as this one, to distract Germans from incursions by real paratroopers.
PHOTOGRAPH BY KENNETH W. RENDELL, INTERNATIONAL MUSEUM OF WORLD WAR II

While the German 15th Army remained in place around Calais to defend against that anticipated thrust, the Allies reinforced their Normandy beachhead by constructing artificial harbors called mulberries, using components prefabricated in British ports and towed across the English Channel.

Mulberry A, completed off Omaha Beach in mid-June and linked to shore by a pontoon bridge, was wrecked a few days later by one of the worst storms to hit the coast that season. Mulberry B, constructed off Gold Beach near Arromanches, withstood that storm and helped boost Allied strength in Normandy to one million men by early July.

SUPPLY LINE
Landing craft disgorge tanks and trucks at Omaha Beach on June 8, 1944, under barrage balloons whose mooring cables deterred enemy aircraft.
PHOTOGRAPH BY U.S. NATIONAL ARCHIVES

Reinforcements for the troops who landed on D-Day were essential because expanding the beachhead proved even tougher than establishing it on June 6. Inland from the beaches lay the forbidding bocage, consisting of low fields surrounded by dense hedgerows that sheltered German snipers, machine gunners, and anti-tank units. Not until June 27 did American troops seize the deepwater port of Cherbourg, which German demolition teams rendered useless until later that year.

Another important objective, heavily defended Caen, was not taken on D-Day, as Montgomery planned, and held out against repeated attacks. On June 13, the British Seventh Armoured Division tried to outflank Caen but was repulsed at Villers-Bocage by elements of the First and Second SS Panzer Divisions.

Allied bombers blasted Caen on July 6, killing many French civilians but few Germans, who withdrew south of the city and resisted tenaciously as Montgomery tried to punch through their defenses. Although held in check, his forces kept several German armoured divisions tied down while American troops prepared to launch Operation Cobra from Saint-Lo^, west of Caen, and break out of the beachhead.

SPY GEAR OF THE FRENCH RESISTANCE

Tools and arms were supplied to agents or French Resistance fighters known as the maquis pictured near Paris in August 1944.
PHOTOGRAPH BY ORONOZ/ALBUM

Beginning of the end

Although the landings on D-Day were less costly than Allied leaders feared, American forces destined for Omaha Beach paid a dreadful price before securing that sector. Casualties mounted as invasion forces advanced inland and met with fierce resistance. Not until late July did they break out, aided by devastating air raids that gouged holes in enemy lines through which armour advanced, including tanks of Patton’s U.S. Third Army. On August 15, a second Allied invasion designated Operation Dragoon unfolded on the French Mediterranean coast. Resistance groups took up arms, and some began liberating Paris before Allied troops entered the city in late August.

WATCH THIS VETERAN FLY IN THE SAME WWII PLANE HE JUMPED FROM ON D-DAY

The offensive in France and the Low Countries coincided with a massive onslaught by the Red Army, whose troops advanced into German-occupied Poland before invading Germany proper by entering East Prussia. Hitler refused to concede defeat and launched a desperate counterattack at year’s end against the Western Allies, whose advance had stalled as they ran short of supplies and came up against the formidable West Wall (Siegfried Line) along the German border.

The resulting Battle of the Bulge, won in January 1945, delayed their advance across the Rhine until March while vengeful Soviets closed on Berlin. “We may be destroyed,” Hitler had remarked earlier, “but if we are, we shall drag a world with us—a world in flames.” On April 30, with Berlin in flames and about to fall to the Russians, he committed suicide. A week later, Germany surrendered unconditionally.

This article is excerpted from Atlas of World War II, published by National Geographic Books. Copyright 2018
PHOTOGRAPH BY NATIONAL GEOGRAPHIC

 

Neil Kagan and Stephen G. Hyslop have partnered on many history books, including Eyewitness to the Civil War, Atlas of the Civil War, Eyewitness to World War II, and The Secret History of World War II.

 

Lead Image: Following months of top-secret planning, U.S. Army troops wade ashore from a landing craft to Omaha Beach, Normandy, on June 6, 1944: D-Day.
PHOTOGRAPH BY GRANGER/ALBUM

Related Articles

Discuss this article

Newsletter

Never miss a Nat Geo moment

Your email address
Submit
We use our own and third-party cookies to improve our services, personalise your advertising and remember your preferences. If you continue browsing, or click on the accept button on this banner, we understand that you accept the use of cookies on our website. For more information visit our Cookies Policy AcceptClose cookie policy overlay