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Part 1, The Buildup


The Allies had been considering a decisive return to “Fortress Europa,” since 1942, the delay of time directly commensurate with the scale of the challenge.


In December 1941, after the Japanese attack on Pearl Harbor and the subsequent entry of the United States into the war, pressure began to build for Washington D C to press for a prompt invasion of Europe, preferably before the end of 1942. General George C Marshal, the US Army Chief of Staff, desperately needed action for his troops to justify Washington’s “Germany first” policy while simultaneously silencing the US Navy, which sought more troops and equipment for the Pacific theater of operations. From 1942, Marshal authorized Operation “Bolero,” a buildup of US forces in Britain for the eventual return to Europe. But the British, especially Prime Minister Winston Churchill, were apprehensive about a cross-channel invasion in 1942 or even 1943 – a prospect made all the more uneasy by the disastrous Dieppe raid of August 1942, a testbed case for a cross-channel assault which led to most of the landing forces being killed or captured.

ABOVE A contemporary painting by Barnett Freedman. shows the interior of the busy Headquarters Room in Southwick Park, Portsmouth during preparations for the D- Day landings. The wall map encompasses southern England, the English Channel and northern France, with various annotations being added. IWM ART LD 4638

That failure had strained the Anglo-American alliance, unhelped by the fact that the Americans were forced to contribute troops and resources to what they considered to were “sideshow operations” in the Mediterranean theater which was so dear to Churchill’s heart. The resentment was fueled by American suspicions that such sideshows were for the benefit of Britain and its plans to re-establish its Mediterranean empire once the war was over. Nevertheless, during the Casablanca conference of January 1943, the question of a cross-channel invasion of France was settled. The invasion would take place sometime after 1 May 1944 and would be codenamed “Overlord."

Two months after the conference, British Lt-General Frederick Morgan was appointed Chief of Staff to the Supreme Commander (although no one had been appointed to this role yet). On Morgan’s shoulders lay the daunting task of formulating preliminary plans for the invasion.  


At their London headquarters in Norfolk House, St James Square, Morgan and his staff began to tackle some of the more pressing problems of a cross-channel invasion. First, they had to select the landing area. Then they had solve the daunting problems of transport, supply and support. Normandy was chosen because it was well within fighter range and it was less well defended than the much closer Pas de Calais area – the first choice. In addition, if the port city of Cherbourg, in the Cotentin peninsula, could be captured early, then the issue of supply could be considerably resolved.

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“Ike? Nice chap. No General.” Bernard Montgomery

The icy relationship between British General Bernard Montgomery (left), commander of the British 21st Army Group, and his superior, the five-star US General Dwight D Eisenhower is evident in this photograph. The men had a less than amicable relationship primarily due to Montgomery's belief that Eisenhower was more a administrator than a strategist. Certainly, Eisenhower's acute strengths in management had driven his promotion through the ranks. IWM ART LD 4638

By when the plans were completed by the end of the year, US General Dwight D Eisenhower had been chosen as Supreme Commander. Almost immediately, in January 1944, planners ran into a problem in the form of British General Bernard Montgomery, victor of the North African campaign. After having returned to England by ship on January 2, fresh off his Mediterranean conquests, “Monty” did not have a high opinion of “Ike” as the American supreme commander was known. “Nice chap,” he said. “No general.”


Next, Montgomery stirred up trouble by insisting that Morgan’s plan was flawed. It was not an unfair estimation. Morgan’s plan called for an invasion force of three divisions to land on three beaches and use the combined firepower of their units to force a breakthrough. But Montgomery saw this narrow point of operation as a liability rather than strength. Within three days of his arrival, he was promoting his own of strategy of landing six divisions on five beaches stretching all the way from the seaside town of Ouisterham in the east, to the base of the Cotentin Peninsula in the west, an area that would eventually become “Utah” beach. Montgomery also wanted a force of three airborne divisions landing at night behind the coast, to protect the flanks, to capture important installations and to sow confusion within the enemy. Finally, Montgomery replaced the entire staff of the 21st Army Group with his own staff from the British Eighth Army, which he had led to victory in North Africa.


On paper, Montgomery’s tweaks were sensible. Allied High Command formally accepted Montgomery's updated plan on January 23 and by April, the strategy was being polished. The Americans were to land on the western flank, while the British-Canadians landed on the east. This was logical, for if the Americans captured Cherbourg, Brest and the Loire ports, then replacements and supplies could be sent direct from the United States without the delays inherent in an England stopover.

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​A meeting of the Supreme Command, Allied Expeditionary Force, in London on 1 February 1944. Left to right, front row: Air Chief Marshal Arthur Tedder Deputy Supreme Commander, Expeditionary Force, General Dwight Eisenhower, Supreme Commander, Expeditionary Force and General Sir Bernard Montgomery, Commander  of the British 21st Army Group. (Back row): Lt-General Omar Bradley, commander US 1st Army, Admiral Sir Bertram H Ramsay, Allied Naval Commander-in-Chief (Expeditionary Force), 

Air Chief Marshal Sir Trafford Leigh-Mallory, Allied Air Commander in Chief (Expeditionary Force) and Lt-General Walter Bedell Smith, Chief of Staff to Eisenhower.

Meantime, forces in England were activated for operations. Two mobile brigade combat groups were placed on standby in Kent and Sussex to deal with German commandos who could potentially land to disrupt the build-up. Not that the Germans would make such an attempt. By now, Britain was an island bulging at the seams with men and equipment crammed in every available base and field. Since 1942, Marshal had dispatched thousands of US troops to Britain, as well as vast amounts of supplies. The island groaned under the weight of 2,000 camps and airfields populated by 950,000 US troops and 600,000 British, commonwealth and Free Force servicemen organized into 20 US and 16 British, Canadian, and Polish divisions. On top of the thousands of American GIs already in Britain, another 37 US divisions were to slated to arrive in Europe, either to decamp in Britain or land directly in Europe after the invasion.


Whole sweeps of the horizon in the southern England were covered with row upon row of tanks, artillery guns, armored cars, aircraft and tents or Nissen huts housing battalions of men. People driving in the southern counties came upon an airfield every five miles, housing entire groups of bombers or fighters. Farmers’ fields were home to a strange harvest – field guns and howitzers, while half-cylindrical steel containers sheltering piles of ammunition lined the grassy shoulders of the country roads. A joke went around that only the thousands of barrage balloons floating up in Britain’s skies kept it from sinking beneath the waves.          


In addition, every formation needed camps in Britain, trains to move them, areas for training and supplies. Each armored division required the equivalent of 40 ships to reach France, almost 386,000 ship tons compared to 270,000 tons for an infantry division. The American initial landing force would comprise of 130,000 men, with another 1,200,000 men following behind by D+90. With them would also go 137,000 jeeps, trucks and half-tracks, 4,217 tanks and full-tracked vehicles and 3,500 artillery pieces. Some five million tons of supplies were needed to feed and supply these troops.

US troops help entertain British children in Britain before D-Day.

Despite being "oversexed and over here," American troops quickly 

bonded with the British.

An American soldier helps children skip rope in a town in the south of England lined as US Army equipment lines the street, headed for Normandy. Getty Images

Yet, despite their careful attention to detail, Allied planners overlooked one crucial factor: the challenges posed by the French bocage on military operations. That the fighting in Normandy would largely devolve into close-combat style battles dictated by the hedgerow, was improperly investigated, and would create formidable headaches later.


US Army engineers of the Office of the Chief of Engineer (OCE) Intelligence Division who had been given the task of preparing 1:25,000 scale battle maps covering 16,000 square miles of northern France, even omitted fine details in their maps such as hedgerows to meet their deadlines for D-Day. In recompense, they included a photomap of the area with each map.

Normandy Bocage

Typical bocage country, a maze of hedgerows, sunken roads and overgrown foliage. Unknown

More egregiously, allied troops were untrained for the the kind of close-range fighting they would find in Normandy. One example was the British 7th Armored Division, the famed “Desert Rats” who had earned their name in the North African campaign. This division was still training in the flatlands of East Anglia.


Neither the fact that the Germans were masters in defense nor that they had the capacity for fierce resistance, especially in the closed-knit areas of the bocage, was properly considered. As a senior staff officer later said: “We simply did not expect to remain in the bocage long enough to justify studying it as a major tactical problem.”


The final invasion plan called for four Allied corps to land troops on five beaches. On the far left at “Utah” beach, the US VII Corps would send in the US 4th Infantry division; at “Omaha,” the US V Corps would be led ashore by the American 1st and 29th Infantry Divisions; at “Gold,” the British XXX Corps would send in the 50th British Division. At “Juno,” the British I Corps would be led in by the 3rd Canadian Division, and at “Sword,” by the 3rd British Infantry Division. Following the landings, the US 1st Army, comprising the V and VII Corps, had to drive up and “capture Cherbourg with minimal delay.” The emphasis was to secure the area north of the Douve river and east of the Merderet river to protect the landing zone. The US 82nd Airborne Division was to secure the western edge of the peninsular invasion zone, particularly the town of St. Mere-Eglise, while the 101st Airborne Division was to secure the beachhead by seizing four roads leading from the beach across the inundated area.


The US 4th Infantry Division would establish the beachhead at "Utah" and drive on Cherbourg with the US 90th Infantry Division, which was scheduled to land on D+1. However, the 90th’s 359th Regimental Combat Team was attached to the 4th Infantry for D-Day operations.


The British Second Army meantime, comprising I and XXX Corps would take Caen to tie down and batter German forces coming from Northern France and the Low Countries. Later, reinforcements, primarily in the form of the US Third Army commanded by the firebrand US Lt-General George S Patton would arrive from England and drive south, clearing Brittany, seizing Nantes and St Nazaire, to cover the southern flank.


“Overlord” was meant to be a masterfully orchestrated assault. But from the outset there were problems. 


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Air power before “Overlord” was a prickly problem. Not that there was any shortage of men and machines. The Allies had access to a seemingly endless line of squadrons equipped with heavy bombers to light bombers, fighters to fighter-bombers, reconnaissance machines to transports. Usage was the problem.

For one, wrangling the heavy bombers of the Royal Air Force’s (RAF) Bomber Command had been prickly proposition as much as its commander, Air Marshal Arthur “Bomber” Harris, was intractable. As one of the so-called Allied “Bomber Barons” who believed that air power alone and the pummeling of cities could bring the Germans to heel, Harris was loathe to reallocate his command to supporting the ground forces tasked with carrying out the invasion. The American 8th Air Force, which was also flying out of Britain under the command of US Lt-General Carl Spaatz, was a different animal but no less slaved to its raison de’etre of air superiority over all other considerations.

A plan was needed to coalesce Allied air power into combined operations by the army and navy against the Germans in Normandy. In February 1944, Montgomery along with Admiral Bertram Ramsay, commander of the Allied expeditionary naval forces, and Air Chief Marshal Leigh-Mallory, came up with a joint plan detailing the role of the three services (air, ground, sea) before and during the invasion. The air component of "Overlord" called for the air forces to knock out the German Luftwaffe and destroy communication links in France. The Allies had four air forces for this task: Harris' Bomber Command, the British 2nd Tactical Air Force (TAF), the American 8th Air Force and the American 9th Air Force.

Hawker Typhoons

Hawker Typhoon Mark IBs of the British Royal Air Force's 175 Squadron watched by armorers at work on another Typhoon of 245 Squadron. This aircraft formed the backbone of the British 2nd Tactical Air Force. IWM CL 449

The “Preparatory Phase” ordered the intensification of attacks on the Luftwaffe, both in the air and the ground.

Divided into two stages, the Preparatory Phase’s first stage called for “concentrated attacks against servicing, repair, maintenance, and other installations, with the intention of reducing the fighting potential of the enemy air forces,” while the second stage were designed to ‘render unserviceable all airfields within 210 km (130 miles) of the assault beaches, the purpose being to drive the Luftwaffe back to a distance where it would have lost the advantage of being based near the front, from where they could have struck back at the landing forces and at airfields in southern England.

The second phase called for isolating the battlefield by interdicting road and rail networks. Once the invasion began, Allied air forces would concentrate on battlefield interdiction and close air support. However, to keep the “Overlord” landing areas secret, deceptions had been planned to encourage the Germans to devote much of their attention in the Pas de Calais region. Allied strike planners therefore had to schedule vastly more operations across the range of likely landing sites rather than just at the true sites in Normandy. For example, rocket-armed Typhoon fighter-bombers of the 2nd Tactical Air Force attacked two radar installations outside the planned assault area for every one they attacked within.

Allied heavy bombers began cratering France and Germany, while the RAF’s fighter-bombers and American B-26 Marauders went after smaller strategic targets: V-1 Flying Bomb launch sites and radar bases in France, Belgium and Holland.

A Free French pilot, Flight Lt Pierre Closterman recalled one such attack site in April: “Like a fan spread out, all the Spitfires turned on their backs one after the other and dived straight down. This time the flak came up straight away. Clusters of tracers began to come up towards us…Shells burst to the left and right, and just above our heads a ring of fine white puffs from the 20 mm cannons began to form, scarcely visible against streaky cirrus clouds. I had only just begun to get the target in my sights when the first bombs were already exploding on the ground – a quick flash followed by clouds of dust and fragments.”  

Meanwhile, swarms of low-flying Bristol Beaufighters and DeHavilland Mosquitoes ranged over the North Sea, mauling German supply ships bound out of Norway and filled with precious iron-ore. The rocket-armed RAF fighters created a ring of fire stretching from Norway to Holland, and soon nothing could sail in daylight without risking blazing cannon-fire and the murderous rocket-strikes. And the RAF wasn’t alone in these interdiction missions. From early May, long-range US P-51 Mustangs and P-38 Lightnings were given the task of smashing the French rail network east of Paris, while the region over the landing areas became the hunting ground for squadrons of American P-47 Thunderbolts.

Beginning in April and continuing with increased vigor in May, allied fighter-bombers went after the Luftwaffe’s airfields and bases in Western Europe, with the ultimate aim of neutralizing all airbases within 210 kilometers (130 miles) of the invasion beaches. During the month of May, 36 major airfields from Brittany to Holland were hit once or repeatedly, but these were not the only targets open to attack. Locomotives, motorized transports, and even bridges were not safe.

Bombed Marshalling Yard

A low-level oblique aerial photograph of smashed rolling stock at the marshalling yards at Juvisy-sur-Orge, France. The yards hut by bombers on the nights of 18/19 April and 7/8 June 1944, in support of the Allied invasion of Normandy. IWM CL 4170

Marshalling yards became sponges for medium bomber raids, and between March 1 and June 5, thirty-six such assembly yards in Belgium and northern France were hit in 139 attacks. The important yard at Creil, near Paris was hit so severely on May 24, that nearly 60 percent of it lay in shambles. Then in a series of raids in May bizarrely named (but perhaps aptly) “Operation Chattanooga Choo-Choo,” American Thunderbolts went after trains, rolling stock, and rail bridges. Rail bridges on the Seine and the Meuse rivers were given first priority. By June 4 the 10 rail bridges between Rouen and Conflans were decisively knocked out, as were all but one of the 14 road bridges.

Rolling stocks were subject to punishing treatment. On 21 May, the most active day for this type of work, some 500 aircraft claimed 46 locomotives as destroyed and another 32 damaged. In addition, a further 30 trains were claimed as damaged. By the end of the month, more than 500 locomotives had been damaged and thousands of passenger cars, boxcars and flat cars lay by the rails, blown to pieces. Rail traffic in France dropped to 35 percent of its March capacity. 

The foundation for these types of operations had been built back in November 1943, when the Allied Expeditionary Air Force (AEAF) was formed and took charge of all air forces designated for support of the Allied assault in June 1944. The stocky Leigh-Mallory was given command of the formation and effectively held overall control of the 2nd Tactical Air Force and the American 9th Air Forces as well elements of the American 8th Air Force. Other subordinate units, such as No 38 Group handled the transport of airborne forces, while the 34th (Reconnaissance) Wing, along with its Spitfires and Mustangs flew over the landing areas and inland, photographing German defenses. Meantime, the RAF’s light bombers of No 2 Group were employed in medium-level pattern bombing against radar sites, airfields and rail yards, whereas its Mosquitoes concentrated on very highly defended vital targets.

The Germans, secure in their bunkers, never expected such a coordinated attack and had no answer for it. There were just too many rail tracks to watch, too many bridges to patrol and too many important locations to defend. The Allied flew more than 200,000 sorties in this preparatory period, dropping about 200,000 tons of bombs dropped on targets in France and Germany. But the cost was high, and about 2,000 Allied aircraft were shot down with the loss of more than 12,000 fliers, excluding an equal number of French and Belgian civilians – victims of the bombing.

That the attacks were effective is beyond doubt. As one German report testified on June 3: “Paris has been systematically cut off from long distance traffic, and the most important bridges over the Seine have been destroyed one after the other. It is only by exerting the greatest effort that military traffic…can be kept moving.” Also, by June, the Luftwaffe in the west had been reduced to a force of 173 fighters to throw against the invasion. In contrast, the combined strength of the Allied air forces amounted to 10,000 combat aircraft, half of them fighters.   

But if this is any positive reflection on the British and American command community, the reality was far different. In the months before the invasion, the level of mutual dissatisfaction rose to such a level that it caused major problems for Eisenhower and his deputy, Air Chief Marshal Arthur Tedder. The problem? All three important subordinate commands had gone to Englishmen – Sir Bernard Montgomery on land, Sir Bertram Ramsay at sea, and Sir Trafford Leigh-Mallory in the air.


Air Chief Marshal Sir Trafford Leigh-Mallory's task was to assist the preparation of and provide the air support for Operation "Overlord." However, his role became diminished due to his inability to get along with his American colleagues. This forced Air Chief Marshal Tedder, Deputy Supreme Commander, to discharge these duties instead. Leigh-Mallory faded from the scene after he was killed in a plane crash in November 1944. Imperial War Museum (IWM)

The stout and aggressive Leigh-Mallory was especially problematic. He had come into the limelight during the Battle of Britain when he had commanded the RAF's No 12 Group protecting the area north of London and the midlands. As an advocate of massed fighter attacks on German bombers (“Big Wing”), he had brushed many the wrong way by repeatedly committing large unwieldy forces against the Germans while not achieving favorable results for the effort expended.

His personal standing was not helped when he took over the commands of Air Vice-Marshal Keith Park and Air Marshal Dowding, the true victors of the Battle of Britain, after they were ousted by those in the Air Ministry who favored Leigh-Mallory. Now in 1944, he was not only unpopular among the British but also among the Americans, who saw him as gloomy, hesitant and conservative. In late 1943, Brigadier-General James “Jumping Jim” Gavin of the 82nd US Airborne Division, who had returned from airborne operations in Sicily to help plan "Overlord," was asked by Leigh-Mallory to describe airborne operations.

“Now I want you chaps to tell me how do this airborne business,” Leigh-Mallory had said. But after listening to Gavin and his staff for a while, he then remarked flatly: “I don’t think anybody can do that.”

Gavin exploded: “What do you mean nobody can do that? We just got through doing it in Sicily!”

Meantime, since March 1944, the US 8th Air Force had been fighting a series of prolonged battles with the German Jagdwaffe (Fighter force) over the Reich. With the RAF flying fighter sweeps over Normandy and south of the Seine river, and with American P-51 Mustangs prowling over eastern France and Germany, the Luftwaffe began to lose the war of attrition.

However, the claims of destruction meted out to the German Luftwaffe proved so fantastic that many in Allied circles proved unwilling to accept them. This skepticism prompted the broaching of elaborate plans to cover the landings, in anticipation of a huge battle for air supremacy over the beachheads.


One SHAEF (Supreme Headquarters Allied Expeditionary Force) estimate assumed that between 300 and 400 German fighter aircraft would contest the landings.  Leigh-Mallory, in typical overcompensation, feared that the Germans would strike at “Overlord’s” weakest links – the invasion fleet at Britain’s south ports.

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