Preparations for D-Day

By the end of April 1944 preparations for the invasion of France had entered their final phase, and on 30 April, the last day of the month, they were in full swing across the whole south of the country. Southern England had become one vast military camp: tents and huts stood in woods and parks, rows of tanks, lorries and guns lined the roads, and hundreds of warships and landing craft lay moored in harbours and estuaries from Cornwall to Kent. The Supreme Commander of the Allied Expeditionary Force, General Dwight Eisenhower, and the commander of the invasion’s ground forces, General Bernard Law Montgomery, had a little over a month left. The date of the landing, hidden under the code name “D-Day”, was known only to a small circle of officers, but the scale of the preparations could no longer be concealed – only their purpose could.

The road to April 1944

The Western Allies had decided on a landing across the English Channel in 1944 in May 1943 in Washington, and in November, at the Tehran Conference, Franklin Delano Roosevelt and Winston Churchill promised Joseph Stalin that the second front would be opened in May 1944. A draft plan had been prepared in London by Lieutenant General Frederick Morgan’s COSSAC staff. From January 1944, when Eisenhower arrived in London and Montgomery took command of 21st Army Group, the plan was thoroughly reworked: instead of three divisions, five were to land in the first wave, on a wider stretch of the Normandy coast, with three airborne divisions on the flanks. A bigger landing required more landing craft, which had to be built or brought from the Mediterranean. That was why the date was moved from May to the beginning of June – an extra month of production in American and British shipyards yielded several hundred more vessels. In February SHAEF headquarters was formally established and the operation took its final shape: “Overlord” meant the whole campaign in Normandy, and “Neptune” its naval and assault phase.

In the spring of 1944 all these decisions had to be turned into men, equipment and orders. April was the month in which this machine ran at full throttle – and in which the high command increasingly thought not about what was still lacking but about how to avoid betraying what was already in place.

An army on an island

The most visible sign of the preparations was the men. Since 1942, under Operation Bolero, one American division after another had been arriving in Britain, along with air force units and supply services. In the spring of 1944 the pace quickened still further: according to American figures, by May there were already some 1.5 million US servicemen in the British Isles. Most of the Americans, destined to land on the western beaches, were billeted in camps in south-west England – in Cornwall, Devon, Somerset and Dorset – while British and Canadian units were further east, between Southampton and Newhaven, and on the east coast. Alongside them, French, Norwegian, Dutch and Belgian troops awaited their turn, as did the Polish 1st Armoured Division of Brigadier General Stanisław Maczek, which was to cross to France in a later wave.

Convoys of lorries took to the country lanes, and fields and heaths were turned into dumps of ammunition, fuel and equipment. The American supply services stockpiled millions of tons of stores in England – from tanks and locomotives to rations and medicines. Quays and hards for loading vehicles were built along the coast, and field hospitals ready to receive the wounded from France grew up beside the camps.

The troops trained in conditions as close to the real thing as possible. In April large-scale landing exercises with live ammunition were held on the beaches of Devon, near the village of Slapton, which had been evacuated earlier. One of them ended in disaster: on the night of 27/28 April German E-boats attacked a convoy taking part in Exercise Tiger, and several hundred American soldiers and sailors were killed. The tragedy at Slapton Sands was immediately hushed up. Early in May came the last great dress rehearsal, Exercise Fabius.

The staffs, meanwhile, were refining the plan. On 7 April, at St Paul’s School in London, which housed the headquarters of 21st Army Group, Montgomery presented to the army, corps and division commanders the detailed course of the land operation, and in the weeks that followed the orders filtered down ever further, to battalion and company commanders.

Harbours of concrete and a pipeline under the sea

The experience of the Dieppe Raid in 1942 had convinced the Allies that they could not take a strongly defended French port at the first attempt. Yet large supply ships needed deep water and quays with cranes. The solution was to be two artificial harbours, code-named Mulberry – “A” for the Americans off Omaha and “B” for the British off Arromanches. Their framework consisted of old ships deliberately scuttled (“corncobs”) to form sheltered anchorages (“gooseberries”), and huge reinforced-concrete “Phoenix” caissons, towed across the Channel and sunk as breakwaters. Inside were to be floating piers and roadways on pontoons that rose and fell with the tide. In the spring of 1944 some 37,000 workers built the components of the harbours in secret in docks, shipyards and on beaches all over Britain; the finished caissons were temporarily sunk off the south coast, to be raised and towed away at the right moment.

An equally bold idea was PLUTO (“Pipe-Line Under The Ocean”) – a pipeline on the bed of the Channel that was to supply the armies with fuel without exposing tankers to attack and storms. The British Petroleum Warfare Department developed two types of pipe: a flexible one, similar to a telegraph cable, and a rigid one of welded steel tubing, wound on floating drums the size of a building, called “Conundrums”. The pipeline, however, came too late to play a part in the first weeks of the invasion – the first line, from the Isle of Wight to Cherbourg, began working only in September 1944, and most of the fuel later arrived by a shorter route from Dungeness to Boulogne.

Landing craft were the hardest thing to come by. Normandy alone required several thousand warships and landing vessels, including several hundred large tank landing ships (LSTs) – and yet those same vessels were indispensable at Anzio and in the Pacific. In April Churchill complained in a letter to General George Marshall that the destinies of two great empires seemed to be tied up in “some god-damned things called LSTs”. American shipyards, including those on rivers far inland, worked flat out, and every vessel capable of crossing the Atlantic was sent to England that spring.

Secrecy

Preparations on such a scale could not be hidden from Britain’s own citizens, but the rest of the world could be cut off from them. From 1 April 1944 visitors were banned from a coastal belt 10 miles (about 16 km) deep, stretching from the Wash in the east to Land’s End in Cornwall. The zone was guarded by checkpoints, and in the most sensitive places even carrying cameras and binoculars was forbidden. Earlier, in March, the British had suspended travel to neutral Ireland, where a German legation was still operating.

On 17 April the British government resorted to a measure without precedent in diplomatic relations: foreign missions in London – except those of the United States and the USSR – lost the right to send cipher telegrams and uncensored diplomatic bags, and their staff were not allowed to leave the country. The restriction also hit allies, including the governments-in-exile and General Charles de Gaulle’s French Committee of National Liberation, which took deep offence. At the end of April ordinary travellers were also stopped from going abroad, and censorship was extended to soldiers’ letters.

Access to the greatest secret – the place and date of the landing – was restricted to officers with the highest clearance, designated by the code word “Bigot”. The last step was planned for the end of May: the troops assigned to the first waves were to enter guarded marshalling camps near the embarkation ports. These were marked on maps by elongated oval shapes, which gave them their popular name, “sausages”. Once the gates were shut no one could leave or contact the outside world, and the soldiers learned the details of their tasks from maps on which the place names had been changed.

The army that never was

Since the preparations could not be hidden, the Germans had to be persuaded that they served a different purpose. That was the aim of Operation Fortitude, part of the wider Allied deception plan Bodyguard. Its northern part was to feed German fears of a landing in Norway; its southern part – Fortitude South – was to convince them that the main blow would fall on the Pas-de-Calais, the stretch of the French coast closest to England, and that a landing anywhere else would be merely a diversion.

The instrument of this deception was the First United States Army Group (FUSAG), a formation that genuinely existed as a headquarters but consisted largely of fictitious divisions “stationed” in south-east England, opposite Calais. It was originally headed by General Omar Bradley, but “command” soon passed to General George Patton. The Germans considered him the most dangerous of the Allied commanders, so it was hard to believe that he would play no part in the invasion. Patton, who was in reality preparing the Third Army for battle, visited units and made public appearances, and his careless speech at Knutsford on 25 April very nearly cost him his post.

The phantom army was built above all over the airwaves – radio stations transmitted the messages of non-existent headquarters – and through double agents turned by British counter-intelligence. The most valuable of them was the Spaniard Joan Pujol García (“Garbo”), whom the Germans trusted so much that his invented network of 27 informants became one of their main sources of knowledge about England. Dummy landing craft in the estuaries of the east coast played a smaller part, because German reconnaissance aircraft hardly ever reached the British Isles any more. On the other side of the Channel, Field Marshal Erwin Rommel, who since December 1943 had been strengthening the Atlantic Wall, and the Commander-in-Chief West, Field Marshal Gerd von Rundstedt, argued over where to place the panzer divisions. Rommel did not rule out a landing in Normandy, but most of the German high command, with Adolf Hitler at its head, expected the main blow on the Pas-de-Calais.

Bombers under Eisenhower’s orders

April also settled the dispute over the heavy bombers. The commanders of the strategic air forces – Air Chief Marshal Arthur Harris of RAF Bomber Command and General Carl Spaatz, commanding the US Strategic Air Forces in Europe – believed that the war could be won by raids on German cities and industry, and were reluctant to switch to tasks connected with the invasion. On 14 April, however, direction of their operations passed to Eisenhower, who exercised it through his deputy, Air Chief Marshal Arthur Tedder. The tactical air forces, grouped in Air Chief Marshal Trafford Leigh-Mallory’s Allied Expeditionary Air Force, were already under his command.

The bombers’ main task became the so-called Transportation Plan: destroying railway junctions, marshalling yards and repair workshops in France and Belgium, so that the Germans could not rush their reserves to Normandy. Because the bombing had to cover the whole of northern France and not just the area around the future beaches, it did not give away the landing site. It came at a price, however: on the night of 20/21 April the raid on the La Chapelle yards in Paris killed several hundred civilians, and Churchill and part of the British Cabinet feared that such a campaign would turn the French against their liberators. Eisenhower insisted that without it the invasion might fail, and in the end he had his way. At the same time Allied aircraft attacked German airfields, coastal radar stations and flying-bomb launch sites, and photographic reconnaissance covered the entire coast from the Netherlands to Brittany.

Moon, tide and weather

The day of the landing was decided by nature. The planners wanted to land shortly after dawn, on a low but rising tide – so that engineers could destroy the beach obstacles while they were exposed and the landing craft would not be stranded. The airborne landings needed a bright, moonlit night. Only a few days a month met all these conditions; in early June they fell on 5, 6 and 7 June, and the next suitable opportunity – without a full moon – came only around 18–20 June. At the end of April the final date had not yet been announced; in May Eisenhower provisionally fixed 5 June as the day of the invasion.

The greatest unknown remained the weather over the Channel, unpredictable even in summer. A team of meteorologists led by Group Captain James Stagg of the RAF was to supply the forecasts on which it depended whether thousands of ships would put to sea. This proved decisive: on 4 June, with strong winds and low cloud, Eisenhower postponed the operation by a day, and that evening Stagg predicted a brief improvement in the weather that allowed the landing to begin on 6 June.

Place in the war

April 1944 was the last full month of preparations for the largest amphibious operation in history. The Western Allies had turned Britain into a springboard for an army of more than two million men, built equipment never seen before and – thanks to strict secrecy and Fortitude – preserved surprise as to where the blow would fall. For the Soviet Union, which for three years had borne the main weight of the land war against Germany, it was at last proof that the promised second front was coming.

On 6 June 1944 the Normandy landings opened a campaign that within three months liberated most of France. The Mulberry harbour at Arromanches served the Allies for ten months, although the American harbour off Omaha was wrecked by a storm on 19 June. The Fortitude deception worked for longer than anyone had expected: for several weeks after the landing the Germans kept the Fifteenth Army in the Pas-de-Calais, waiting for Patton’s second, “real” blow. The price of the preparations and of the fighting in Normandy was also paid by French civilians – the victims of the railway bombing of spring 1944 and of the Normandy towns destroyed that summer.