In June 1940, Germany's leader
Adolf Hitler had triumphed in what he called "the most famous victory in history"—the
fall of France. British craft evacuated to England over 338,000 Allied troops trapped along the northern coast of France (including much of the
British Expeditionary Force) in the
Dunkirk evacuation (27 May to 4 June). British planners reported to Prime Minister
Winston Churchill on 4 October that even with the help of other
Commonwealth countries and the United States, it would not be possible to regain a foothold in continental Europe in the near future. After the Axis
invaded the Soviet Union in June 1941, Soviet leader
Joseph Stalin began pressing for a
second front in Western Europe. Churchill declined because he felt that even with American help the British did not have adequate forces to do it, and he wished to avoid costly frontal assaults such as those that had occurred at the
Somme and
Passchendaele in
World War I. Two temporary plans code-named
Operation Roundup and
Operation Sledgehammer were put forward for 1942–43, but neither was deemed by the British to be practical or likely to succeed. Instead, the
Allies expanded their activity in the Mediterranean, launching
Operation Torch, an invasion of
French North Africa, in November 1942, the
Allied invasion of Sicily in July 1943, and
Allied invasion of Italy in September. These campaigns provided the troops with valuable experience in
amphibious warfare. Those attending the
Trident Conference in Washington in May 1943 took the decision to launch a cross-Channel invasion within the next year. Churchill favoured continued Allied operations in the Mediterranean rather than an immediate cross-Channel invasion, as a plan had not yet been devised that was likely to succeed. General
George C. Marshall and the
Joint Chiefs of Staff favoured the cross-channel approach. However, historian
Maurice Matloff notes that "a number of misconceptions grew up in the postwar period about this Anglo-American debate over strategy," and that "it is a mistake to assume that the British did not from the first want a cross-Channel operation". Planners of both nations agreed that an invasion would have to be postponed until German forces were weaker, the required landing craft were available, and logistical infrastructure was in place. Marshall ultimately conceded the case for continued Mediterranean operations, as long as it did not impede the efforts toward a landing in northern France. President
Roosevelt's position was to postpone the decision a few months.
Alan Brooke, 1st Viscount Alanbrooke appointed British Lieutenant-General
Frederick E. Morgan as Chief of Staff, Supreme Allied Commander (COSSAC), to begin detailed planning. Alanbrooke commented on the operation, saying, "Well there it is, it won't work, but you must bloody well make it". The initial plans were constrained by the number of
landing craft, most of which were already committed in the Mediterranean and in the Pacific. In part because of lessons learned in the
Dieppe Raid of 19 August 1942, the Allies decided not to directly assault a heavily defended French seaport in their first landing. The failure at Dieppe also highlighted the need for adequate artillery and air support, particularly
close air support, and specialised ships able to travel extremely close to shore. The short operating range of British aircraft such as the
Supermarine Spitfire and
Hawker Typhoon greatly limited the number of potential landing-sites, as comprehensive air support depended upon having planes overhead for as long as possible. Morgan considered four sites for the landings:
Brittany, the
Cotentin Peninsula, Normandy, and the
Pas-de-Calais. As Brittany and Cotentin are peninsulas, the Germans could have cut off the Allied advance at a relatively narrow
isthmus, so these sites were rejected. The Pas-de-Calais, the closest point in continental Europe to Britain, was the location of launch sites for
V-1 and
V-2 rockets, then still under development. The Germans regarded it as the most likely initial landing zone and accordingly made it the most heavily fortified region; however, it offered the Allies few opportunities for expansion as the area is bounded by numerous rivers and canals. On the other hand, landings on a broad front in Normandy would permit simultaneous threats against the port of
Cherbourg, coastal ports further west in Brittany, and an overland attack towards Paris and eventually into Germany. The Allies therefore chose Normandy as the landing site. The most serious drawback of the Normandy coast – the lack of port facilities – would be overcome through the development and deployment of artificial harbours. The COSSAC staff planned to begin the invasion on 1 May 1944. The initial draft of the plan was accepted at the
Quebec Conference in August 1943. General Dwight D. Eisenhower was appointed commander of
Supreme Headquarters Allied Expeditionary Force (SHAEF). General
Bernard Montgomery was named commander of the
21st Army Group, which comprised all of the land forces involved in the invasion. On 31 December 1943, Eisenhower and Montgomery first saw the COSSAC plan, which proposed amphibious landings by three
divisions, with two more divisions in support. The two generals immediately insisted on expanding the scale of the initial invasion to five divisions, with airborne descents by three additional divisions, to allow operations on a wider front and to speed up the capture of the port at Cherbourg. This significant expansion required the acquisition of additional landing craft, which caused the invasion to be delayed by a month until June 1944. Eventually the Allies committed 39 divisions to the Battle of Normandy: 22 American, 12 British, 3 Canadian, 1 Polish, and 1 French, totalling over a million troops.
Allied invasion plan assault routes into Normandy "Overlord" was the name assigned to the establishment of a large-scale
lodgement on the Continent. The first phase, the amphibious invasion and establishment of a secure foothold, was code-named
Operation Neptune and is often referred to as "D-Day". To gain the required air superiority needed to ensure a successful invasion, the Allies launched a strategic bombing campaign (codenamed
Pointblank) to target German aircraft-production, fuel supplies, and airfields. Under the
Transport Plan, communications infrastructure and road and rail links were bombed to cut off the north of France and to make it more difficult to bring up reinforcements. These attacks were widespread so as to avoid revealing the exact location of the invasion. Elaborate
deceptions were planned to prevent the Germans from determining the timing and location of the invasion. The coastline of Normandy was divided into seventeen sectors, with code-names using a
spelling alphabet—from Able, west of
Omaha, to Roger on the east flank of
Sword. Eight further sectors were added when the invasion was extended to include
Utah on the Cotentin Peninsula. Sectors were further subdivided into beaches identified by the colours Green, Red, and White. Allied planners envisaged preceding the sea-borne landings with airborne drops: near Caen on the eastern flank to secure the
Orne River bridges, and north of
Carentan on the western flank. The initial goal was to capture Carentan,
Isigny,
Bayeux, and Caen. The Americans, assigned to land at Utah and Omaha, were to cut off the Cotentin Peninsula and capture the port facilities at Cherbourg. The British at Sword and
Gold, and the Canadians at
Juno, were to capture Caen and form a front line from
Caumont-l'Éventé to the south-east of Caen in order to protect the American flank, while establishing airfields near Caen. Possession of Caen and its surroundings would give the Anglo-Canadian forces a suitable staging area for a push south to capture the town of
Falaise. A secure lodgement would be established and an attempt made to hold all territory captured north of the
Avranches-Falaise line during the first three weeks. The Allied armies would then swing left to advance towards the
River Seine. The invasion fleet, led by Admiral Sir
Bertram Ramsay, was split into the Western Naval Task Force (under Admiral
Alan Kirk) supporting the American sectors and the Eastern Naval Task Force (under Admiral Sir
Philip Vian) in the British and Canadian sectors. The American forces of the
First Army, led by Lieutenant General
Omar Bradley, comprised VII Corps (Utah) and
V Corps (Omaha). On the British side, Lieutenant-General
Miles Dempsey commanded the
Second Army, under which
XXX Corps was assigned to Gold and
I Corps to Juno and Sword. Land forces were under the command of Montgomery, and air command was assigned to
Air Chief Marshal Sir
Trafford Leigh-Mallory. The
First Canadian Army included personnel and units from
Poland, Belgium, and the Netherlands. Other Allied nations participated.
Reconnaissance The
Allied Expeditionary Air Force flew over 3,200 photo-reconnaissance sorties from April 1944 until 6 June 1944. Photos of the coastline were taken at extremely low altitude to show the invaders the terrain, obstacles on the beach, and defensive structures such as bunkers and gun emplacements. To conceal the location of the invasion, sorties were flown along all European coastline. Inland terrain, bridges, troop emplacements, and buildings were also photographed, in many cases from several angles. Members of
Combined Operations Pilotage Parties clandestinely prepared detailed harbour maps, including
depth soundings. An appeal for holiday pictures and postcards of Europe announced on the
BBC produced over ten million items, some of which proved useful. The
French resistance provided details on Axis troop movements and on construction techniques used by the Germans for bunkers and other defensive installations. Many German radio messages were encoded using the
Enigma machine and other enciphering techniques and the codes were changed frequently. A team of code breakers stationed at
Bletchley Park worked to break codes as quickly as possible to provide advance information on German plans and troop movements. British military intelligence code-named this information
Ultra intelligence as it could only be provided to the most senior commanders. The Enigma code used by Field Marshal
Gerd von Rundstedt,
Oberbefehlshaber West (Supreme Commander West;
OB West), commander of the
Western Front, was broken by the end of March. German intelligence changed the Enigma codes after the Allied landings but by 17 June the Allies were again consistently able to read them.
Technology B (Gold) at
Arromanches-les-Bains in Normandy, as seen out at sea and on the beach in 1990 After the disastrous
Dieppe Raid in August 1942, the Allies developed new technologies for Overlord. To supplement the preliminary offshore bombardment and aerial assaults, some of the landing craft were equipped with artillery and anti-tank guns to provide close supporting fire. The Allies had decided not to immediately attack any of the heavily protected French ports and two artificial ports, called
Mulberry harbours, were designed by COSSAC planners. Each assembly consisted of a floating outer
breakwater, inner concrete
caissons (called
Phoenix breakwaters) and several floating piers. The Mulberry harbours were supplemented by
blockship shelters (codenamed "Gooseberries"). With the expectation that fuel would be difficult or impossible to obtain on the continent, the Allies built a "Pipe-Line Under The Ocean" (
PLUTO). Specially developed pipes in diameter were to be laid under the Channel from the
Isle of Wight to Cherbourg by D-Day plus 18. Technical problems and the delay in capturing Cherbourg meant the pipeline was not operational until 22 September. A second line was laid from
Dungeness to Boulogne in late October. The British built specialised tanks, nicknamed
Hobart's Funnies, to deal with conditions expected during the Normandy campaign. Developed under the supervision of Major-General
Percy Hobart, these were modified
M4 Sherman and
Churchill tanks. Examples include the
Sherman Crab tank (equipped with a mine flail), the
Churchill Crocodile (a flame-throwing tank), and the
Armoured Ramp Carrier, which other tanks could use as a bridge to scale sea-walls or to overcome other obstacles. In some areas, the beaches consisted of a soft clay that could not support the weight of tanks. The
Bobbin tank unrolled matting over the soft surface, leaving it behind as a route for ordinary tanks. The
Assault Vehicle Royal Engineers (AVRE) was a Churchill tank modified for many combat engineering tasks, including laying bridges; it was armed with a demolition gun that could fire large charges into
pillboxes. The Duplex-Drive tank (
DD tank), another design developed by Hobart's group, was a self-propelled amphibious tank kept afloat using a waterproof canvas screen inflated with compressed air. These tanks were easily swamped, and on D-Day, many sank before reaching the shore, especially at Omaha.
Deception In the months leading up to the invasion, the Allies conducted
Operation Bodyguard, the overall strategy designed to mislead the Germans as to the date and location of the main Allied landings.
Operation Fortitude included Fortitude North, a misinformation campaign using fake radio-traffic to lead the Germans into expecting an attack on Norway, and Fortitude South, a major deception designed to fool the Germans into believing that the landings would take place at
Pas-de-Calais in July. A fictitious
First U.S. Army Group was invented, supposedly located in
Kent and
Sussex under the command of Lieutenant General
George S. Patton. The Allies constructed dummy tanks, trucks, and landing craft, and positioned them near the coast. Several military units, including II Canadian Corps and
2nd Canadian Division, moved into the area to bolster the illusion that a large force was gathering there. As well as the broadcast of fake radio-traffic, genuine radio messages from 21st Army Group were first routed to Kent via landline and then broadcast, to give the Germans the impression that most of the Allied troops were stationed there. Patton remained stationed in England until 6 July, thus continuing to deceive the Germans into believing a second attack would take place at Calais. Military and civilian personnel alike were aware of the need for secrecy, and the invasion troops were as much as possible kept isolated, especially in the period immediately before the invasion. American general
Henry J. F. Miller was sent back to the United States in disgrace after revealing the invasion date at a party. The Germans thought they had an extensive network of spies operating in the UK, but in fact, all their agents had been captured, and some had become
double agents working for the Allies as part of the
Double-Cross System. The double agent
Juan Pujol García, a Spanish opponent of the Nazis known by the code name "Garbo", developed over the two years leading up to D-Day a fake network of informants that the Germans believed were collecting intelligence on their behalf. In the months preceding D-Day, Pujol sent hundreds of messages to his superiors in Madrid, messages specially prepared by the British intelligence service to convince the Germans that the attack would come in July at Calais. Many of the German radar stations on the French coast were destroyed by the RAF in preparation for the landings. On the night before the invasion, in
Operation Taxable,
617 Squadron (the famous "Dambusters") dropped strips of "window",
metal foil that German radar operators interpreted as a naval convoy approaching Cap d'Antifer (about from the actual D-Day landings). The illusion was bolstered by a group of small vessels towing
barrage balloons.
No. 218 Squadron RAF also dropped "window" near
Boulogne-sur-Mer in
Operation Glimmer. On the same night, a small group of
Special Air Service (SAS) operators deployed dummy paratroopers over
Le Havre and Isigny. These dummies led the Germans to believe an additional airborne assault had occurred.
Rehearsals and security Training exercises for the Overlord landings took place as early as July 1943. As the nearby beach resembled the planned Normandy landing-site, the town of
Slapton in Devon, was evacuated in December 1943, and taken over by the armed forces as a site for training exercises that included the use of landing craft and the management of beach obstacles. A
friendly fire incident there on 27 April 1944 resulted in as many as 450 deaths. The following day, an additional estimated 749 American soldiers and sailors died when
German torpedo-boats surprised members of Assault Force "U" conducting
Exercise Tiger. Exercises with landing craft and live ammunition also took place at the Combined Training Centre in
Inveraray in Scotland. Naval exercises took place in Northern Ireland, and medical teams in London and elsewhere rehearsed how they would handle the expected waves of casualties. Paratroopers conducted exercises, including a huge demonstration drop on 23 March 1944 observed by Churchill, Eisenhower, and other top officials. Allied planners considered tactical surprise to be a necessary element of the plan for the landings. Information on the exact date and location of the landings was provided only to the topmost levels of the armed forces. Men were sealed into their marshalling areas at the end of May, with no further communication with the outside world. Troops were briefed using maps that were correct in every detail except for the place names, and most were not told their actual destination until they were already at sea. A news blackout in Britain increased the effectiveness of the deception operations. Travel to and from the
Republic of Ireland was banned, and movement within several kilometres of the coast of England restricted.
Weather forecasting being briefed for the invasion, 4–5 June 1944 The invasion planners specified a set of conditions regarding the timing of the invasion, deeming only a few days in each month suitable. A full moon was desirable, as it would provide illumination for aircraft pilots and have the
highest tides. The Allies wanted to schedule the landings for shortly before dawn, midway between low and high tide, with the tide coming in. This would improve the visibility of obstacles the enemy had placed on the beach while minimising the amount of time the men had to spend exposed in the open. Specific criteria were also set for wind speed, visibility, and cloud cover. Eisenhower had tentatively selected 5 June as the date for the assault; however, on 4 June, conditions were clearly unsuitable for a landing, as high winds and heavy seas made it impossible to launch landing craft, and low clouds would prevent aircraft from finding their targets. By the evening of 4 June, the Allied meteorological team, headed by Group Captain
James Stagg of the
Royal Air Force, predicted that the weather would improve sufficiently so that the invasion could go ahead on 6 June. He met Eisenhower and other senior commanders at their headquarters at
Southwick House in Hampshire to discuss the situation. General Montgomery and Major-General
Walter Bedell Smith, Eisenhower's chief of staff, were eager to launch the invasion. Admiral Bertram Ramsay was prepared to commit his ships, while Air Chief Marshal Trafford Leigh-Mallory expressed concern that the conditions would be unfavourable for Allied aircraft. After much discussion, Eisenhower decided that the invasion should go ahead. Allied control of the Atlantic meant that German meteorologists did not have access to as much information as the Allies on incoming weather patterns. As the Luftwaffe meteorological centre in Paris predicted two weeks of stormy weather, many
Wehrmacht commanders left their posts to attend war games in
Rennes, and men in many units were given leave. Marshal
Erwin Rommel returned to Germany for his wife's birthday and to meet Hitler to try to get more tanks. Had Eisenhower postponed the invasion again, the next available period with the right combination of tides (but without the desirable full moon) was two weeks later, from 18 to 20 June. As it happened, during this period the invaders would have encountered a major storm lasting four days, between 19 and 22 June, that would have made the initial landings impossible.
German preparations and defences on the
Atlantic Wall in France, 21 March 1944 Nazi Germany had at its disposal 50 divisions in France and the
Low Countries, with another 18 stationed in Denmark and Norway. Fifteen divisions were in the process of formation in Germany, but there was no strategic reserve. The Calais region was defended by the
15th Army under (Colonel General)
Hans von Salmuth, and Normandy by the
7th Army commanded by
Generaloberst Friedrich Dollmann. Combat losses throughout the war, particularly on the
Eastern Front, meant the Germans no longer had a pool of able young men from which to draw. German soldiers were now on average six years older than their Allied counterparts. Many in the Normandy area were
Ostlegionen (eastern legions)—conscripts and "volunteers" from
Turkestan, Russia, Mongolia, and elsewhere. The Wehrmacht had provided them mainly with unreliable captured equipment; they lacked motorised transport. Formations that arrived later, such as the
12th SS Panzer Division Hitlerjugend, were, for the most part, younger and far better equipped and trained than the static troops stationed along the coast. In early 1944, OB West was significantly weakened by personnel and materiel transfers to the Eastern Front. During the Soviet
Dnieper–Carpathian Offensive (24 December 1943 – 17 April 1944), the
German High Command was forced to transfer the entire
II SS Panzer Corps from France, consisting of the
9th and
10th SS Panzer Divisions, as well as the
349th Infantry Division, 507th Heavy Panzer Battalion and the 311th and 322nd StuG Assault Gun Brigades. All told, the German forces stationed in France were deprived of 45,827 troops and 363 tanks, assault guns, and self-propelled anti-tank guns. It was the first major transfer of forces from France to the east since the creation of
Führer Directive 51, which no longer allowed any transfers from the west to the east. There were also transfers to the Italian front: von Rundstedt complained that many of his best units had been sent on a "fool's errand" to Italy, saying it was "madness ... that frightful boot of a country should have been evacuated ... we should have held a decent front with a few divisions on the Alpine frontier." The
1st SS Panzer Division Leibstandarte SS Adolf Hitler,
9th,
11th,
19th and
116th Panzer divisions, alongside the
2nd SS Panzer Division "Das Reich", had only arrived in March–May 1944 to France for extensive refit after being badly damaged during the Dnieper-Carpathian Offensive. Seven of the eleven panzer or panzergrenadier divisions stationed in France were still not fully operational or only partially mobile in early June 1944.
Atlantic Wall Alarmed by the raids on
St Nazaire and Dieppe in 1942, Hitler ordered the construction of fortifications all along the Atlantic coast, from Spain to Norway, to protect against an expected Allied invasion. He envisioned 15,000 emplacements manned by 300,000 troops, but due to shortages, particularly of concrete and manpower, most of the
strongpoints were never built. As the expected site of an Allied invasion, Pas-de-Calais was heavily defended. In the Normandy area the best fortifications were concentrated at the port facilities at Cherbourg and
Saint-Malo. A report by Rundstedt to Hitler in October 1943 regarding the weak defences in France led to the appointment of Rommel to oversee the construction of further fortifications along the expected invasion-front, which stretched from the Netherlands to Cherbourg. Rommel was given command of the newly re-formed
Army Group B, which included the 7th Army, the 15th Army, and the forces guarding the Netherlands. Nazi Germany's tangled command structure made it difficult for Rommel to achieve his task. He was not allowed to give orders to the
Organisation Todt, which was commanded by armaments minister
Albert Speer, so in some places he had to assign soldiers to do construction work. Rommel believed that the Normandy coast could be a possible landing point for the invasion, so he ordered the construction of extensive defensive works along that shore. In addition to concrete gun-emplacements at strategic points along the coast, he ordered wooden stakes,
metal tripods, mines, and
large anti-tank obstacles to be placed on the beach to delay the approach of landing craft and to impede the movement of tanks. Expecting the Allies to land at high tide so that the infantry would spend less time exposed on the beach, he ordered many of these obstacles to be placed at the high-tide mark. Tangles of barbed wire, booby traps, and the removal of ground cover made the approach hazardous for infantry. On Rommel's order, the number of mines along the coast was tripled. Given the Allied air supremacy (4,029 Allied aircraft assigned to operations in Normandy plus 5,514 aircraft assigned to bombing and defence, versus 570 Luftwaffe planes stationed in France and the Low Countries), booby-trapped stakes known as
Rommelspargel (
Rommel's asparagus) were set up in meadows and fields to deter airborne landings.
Mobile reserves Rommel, believing that the Germans' best chance was to stop the invasion at the shore, requested that mobile reserves—especially tanks—be stationed as close to the coast as possible. Rundstedt, General
Leo Geyr von Schweppenburg (commander of
Panzer Group West), and other senior commanders believed that the invasion could not be stopped on the beaches. Geyr argued for a conventional doctrine: keeping the Panzer formations concentrated in a central position around Paris and Rouen and deploying them only when the main Allied beachhead had been identified. Geyr also noted that in the
Italian Campaign the armour stationed near the coast had been damaged by naval bombardment. Rommel's opinion was that because of the overwhelming Allied air superiority, large-scale movement of tanks would not be possible once the invasion was underway. Hitler made the final decision: he left three divisions under Geyr's command and gave Rommel operational control of three tank-divisions as reserves. Hitler took personal control of four divisions as strategic reserves, not to be used without his direct orders. == Invasion ==