# World War II/D-Day - The Allied Invasion

The invasion of Normandy, codenamed 'Operation Overlord', began on June 6, 1944, with the landing of airborne and amphibious troops in Normandy. The initial landing phase of this operation was the largest amphibious operation in history. The invasion culminated in Operation Cobra on July 24.

## Preparation
### Early Planning

Proposals for opening up a 'second front' as early as Autumn 1942 were being considered by the U.S. Joint Chiefs of Staff. An alternate plan, drawn up by then-Brigadier General Dwight D. Eisenhower, proposed a landing before April 1943. While this plan never came to fruition, it brought Eisenhower's organisational and diplomatic skill to the attention of senior political and military leaders in both America and Britain, leading to his rise to Supreme Allied Commander in Europe in less than two years.
Planning for an invasion of occupied France began in earnest after the Casablanca and Tehran Conferences in 1943. The costly failure of the Dieppe raid in December the previous year had ruled out a direct assault on a seaport. The need for air support and proximity to the U.K. narrowed the choice of landing sites to the Pas de Calais and Normandy. While attacking Normandy would pose logistical problems, Pas de Calais was heavily defended, and the rivers and canals in the area would prevent a breakout from the beachheads. As a result, Normandy was chosen to be the landing site.
In March 1943, Frederick E. Morgan, a British Lieutenant General, was appointed Chief of Staff to the Supreme Allied Commander, or COSSAC. During June and July, the COSSAC staff worked on a plan for a full-scale attack on Western Europe. This plan, named Operation Overlord, was presented to the British Chiefs of Staff Committee in mid-July and to the U.S. Joint Chiefs of Staff later that month. This plan envisaged a landing in Normandy, the use of prefabricated Mulberry harbours, the deployment of American forces on the right and British troops on the left, an airborne operation to secure the flanks and seize strategic points and a diversionary operation in the south of France (Operation Dragoon). The plan stated that the operation was to be launched on May 1, 1944.
The COSSAC's plan was accepted at the Quebec Conference in August 1943 but it was several months before a Supreme Allied Commander was appointed. In November, General Eisenhower was appointed Supreme Allied Commander in Europe in preference to U.S. Army Chief of Staff General George C. Marshall. Shortly after, Field Marshal Bernard Montgomery was appointed Commander in Chief of the Ground Forces and Commander of the 21st Army Group. Eisenhower and Montgomery first saw the Overlord plan in December 1943. While the key features of the plan were accepted, Montgomery though that the landing would not succeed unless it was significantly expanded (the original plan called for the landing of three divisions by sea and two brigades by air; it was revised to five divisions by sea and three by air), at the expense of the invasion of southern France. The expansion also delayed the landings by little over a month.
In April and May 1944, Field Marshal Montgomery presented his strategy for the invasion of Normandy. It would involve a ninety-day battle in which the Allied forces would pivot on the town of Caen. In the first forty days, a lodgement in Normandy including Caen and Cherbourg would be created. Once Normandy was secured, there would be a breakout towards Brittany and the Atlantic ports on one flank, and a an assault on Paris on the right.

### Operation Fortitude

One of the most crucial elements of the Allied plan for the landings in Normandy was Operation Bodyguard, a deception plan intended to mislead the Germans as to where and when the attack would come. Bodyguard was divided into a number of components, the most important of which was Operation Fortitude, which, in turn, was divided Fortitude North and South.
Fortitude North was designed to trick the Germans into thinking that an Allied invasion would come in Scandinavia, thus tying down German units there. A fictional army, the British 4th Army, was created, and headquartered in Edinburgh Castle. Double agents were used to feed information about the arrival of troops in the area to the Germans. Fortitude North also involved simulated radio traffic between nonexistent army units. However, the use of false radio traffic failed to achieve anything as the Germans were not monitoring the radio traffic. Commando attacks, designed to look like preparations for a full-scale invasion, and naval activity, increased in Scandinavia. British diplomats began negotiations with neutral Sweden to obtain concessions that would have been beneficial to an invasion of Norway, such as the right to fly reconnaissance missions in Swedish airspace. A secondary effect of diplomatic pressure on Sweden was that the export of crucial ball bearings to Germany was halted.
Fortitude South was intended to convince the Germans that the invasion of France would come at Pas de Calais (this was a logical choice from a geographical standpoint: Pas de Calais is the closest part of France to England), would be executed by the 21st Army Group (which was actually part of the invasion of Normandy) and the American 1st Army Group (which did not exist, and was supposedly under the command of General George S. Patton), and would be preceded by a diversionary attack at Normandy. Fortitude South involved a massive amount of false radio traffic, increased activity around Dover (intended to look like preparations for an invasion), the placement of dummy vehicles and landing craft near Dover and a supposedly pre-invasion bombing campaign against targets near Pas de Calais. The most important part of Fortitude South was the use of double agents loyal to the Allies, including captured German agents, to feed misinformation to the Germans. One particularly important double agent was Juan Pujol Garcia, codenamed Garbo by the British. Operating the Portugal while pretending to be in the U.K., Garbo developed a network of nonexistent agents who were supposedly working for him.
Even after the landings in Normandy, the Allies maintained that the main attack would come in Pas de Calais, tying up German troops which could have been used as reinforcements.

### Preparations for the Landings

Two armies, the British 2nd Army and American 1st Army, were used in the Normandy landings.
The British 6th Airborne Division was to be delivered by parachute and glider to the east of the River Orne to protect the left flank of the attack. The 2nd Army was also responsible for three beaches; from east to west, they were Sword, Juno and Gold. The 2nd Army included some 83 thousand troops, of which approximately a quarter were Canadian.
The American 1st Army included the 101st and 82nd Airborne Divisions. The former was to be dropped Vierville-sur-Mer to support the landing at Utah Beach; the latter was initially tasked with dropping in the middle of the Cotentin Peninsula to ease access to the Peninsula and prevent the Germans from reinforcing it, but, due to the presence of German forces in the drop zone, their mission was changed to guarding the right flank of Utah Beach. Units of the 1st Army would land at Omaha Beach and Utah Beach further west. The 1st Army consisted of about 76 thousand men.
The naval part of the operation, often regarded as a masterpiece of military planning, was under the command of Royal Navy Admiral Sir Betram Ramsay, who had been in charge of the evacuation of British troops from Dunkirk several years earlier, as well as the naval part of the landings in North Africa and Sicily. Almost seven thousand ships were involved, including 1200 battleships and over 4 thousand transports. The vast majority of these ships were British. Of the nearly 200 thousand naval personnel, about sixty percent were British and half that number American, with the rest coming from other countries. The warships were tasked with guarding the transports against submarines, surface ships or attacking aircraft, as well as supporting the landings with a shore bombardment.

### German Preparations

Throughout 1942 and 1943, the Germans had believed that there was very little possibility of a successful Allied invasion of western Europe. While strong fortifications protected the major ports, German preparations for an invasion were otherwise limited. In late 1943, Generalfeldmarschall Gerd von Rundstedt, commander of Oberbefehlshaber West or OB West, the German Army Command in the West, seeing the buildup of Allied forces in Britain, requested reinforcements. Fresh troops were duly sent.
At around the same time, Generalfeldmarschall Erwin Rommel, renowned for his successes in North Africa and regarded as one of the best commanders in the Wehrmacht, arrived in northern France to inspect the Atlantic Wall, as the coastal defences of Western Europe were called. After his inspection, Rommel asked Hitler for command of the defenders of northern France, Belgium and the Netherlands. These units were formed into Army Group B and put under Rommel's command. Rommel realised that the Atlantic Wall only protected the major ports. Thus, he had bunkers and pillboxes built, steel obstacles placed the high-water marks at the beaches and low-lying areas flooded. Booby-trapped stakes (known as Rommelspargel or 'Rommel's asparagus') were set up further inland to deter or disrupt airborne landings.
In addition to static fortifications, Rommel wanted to use the Panzer Group West to defend the coast. However, there was a disagreement on the use of mobile forces. While Rommel wanted to put them close to the coast to use them in a counterattack against the invaders while they were vulnerable, General Leo Geyr von Schweppenburg, the commander of the Panzer Group, wanted to concentrate them in Paris use them in a massive counterattack against the main Allied beachhead. Hitler imposed a compromise: most of the armored and mechanised units would be scattered across France and the Low Countries, while Rommel was given Panzer divisions, of which only one could reach the beaches in one day.

### Exercise Tiger

Allied forces rehearsed their roles in the Normandy landings for months prior to the actual invasion. Exercises began in December 1943.
Exercise Tiger was a full-scale rehearsal of the attack on Utah Beach that occurred in April 1944. Thirty thousand American troops were to participate in the mock landing at Slapton Sands on the coast of Lyme Bay in southern England. Nine German E-boats sighted the convoy of eight landing ships off the coast and attacked. Two landing ships were set on fire, of which one made it back to shore, and another sank shortly after being torpedoed. The remaining ships and their escorts retaliated, and the E-boat attacks ceased. A further landing ship was damaged by friendly fire. In the attack, 638 servicemen were killed. The surviving landing ships proceeded to land on Slapton Sands. General Eisenhower had ordered that the beach be shelled with live ammunition to simulate combat conditions. There was white tape on the beach which the troops were not supposed to advance beyond until the live shelling had stopped; however, some disregarded these orders and 308 men were killed.
Due to embarrassment and fear of leaks, survivors were sworn to secrecy. Ten missing officers had Bigot-level clearance, which mean that they had knowledge of the invasion plans. Fearing that they had been captured alive, the invasion was almost called off. Their bodies were later recovered. The casualty count was not released until after the Normandy landings.

### Weather

The window of opportunity for a successful invasion was limited. A full moon was required, both for a spring tide and light for the aircraft pilots. Thus, there were only a few days each month on which an invasion could happen. Eisenhower selected June 5 as the date for the invasion, that is, D-Day. (While the term 'D-Day' is most often associated with the Normandy landings, as a general military term it refers to the day on which an operation is to begin.) However, on the night June 3, the weather was bad. High winds and low cloud made it unsuitable for a landing. It was forecast that the bad weather would continue for three or four days. At a meeting of senior Allied commanders, Eisenhower decided to postpone the invasion until June 6. If weather did not improve somewhat within forty-eight hours, the invasion would have to be postponed for two weeks. Not only would this have decreased the morale of the Allied troops, who were already being loaded onto the ships, the invasion would have run into what Churchill called "the worst Channel storm in forty years". Early in the morning of June 4, it was agreed at another meeting that the postponement would stand.
Meanwhile, the Germans, confident that the Allies would not launch an invasion in adverse weather conditions, relaxed. Some troops stood down, and many senior officers left, some of them for wargames. Rommel was attending his wife's birthday.
Late on June 4, a meeting of the senior Allied commanders was convened again. Weather forecasts indicated that on June 6, the weather would improve slightly. Air Chief Marshal Trafford Leigh-Mallory, the commander of the air forces, expressed his concern that visibility would be insufficient for the air operations to proceed. However, the other commanders agreed that the operation should go ahead on June 6. At a morning conference the next day, the final decision was made. Overlord was on.

### Coordination with the French Resistance

The leaders of the French Resistance, most of whom were in the U.K., organised a massive sabotage campaign to increase the chances of a successful landing. The Resistance would attack railway lines, ambush roads and destroy other buildings of tactical significance, such as telephone exchanges.
The BBC regularly broadcasted short messages in French to the Resistance. While these messages were seemingly meaningless, the few significant messages, masked by hundreds of meaningless ones, either instructed the resistance to commit a certain act of sabotage or gave them information. For example "Bercent mon coeur d'une langueur monotone" ("soothe my heart with a monotonous languor"), the second line of Paul Verlaine's poem Chanson d'Automne, notified the Resistance that the invasion was imminent. Nazi intelligence had actually discovered the meaning of "Bercent mon coeur d'une langueur monotone", but when military commanders in France were notified, the warning was not heeded as a false alarm had been raised in the past.

## D-Day
### Airborne Operations

The purpose of the airborne operations just prior to the main amphibious landings was to allow the Allied troops to come ashore without being threatened by German counterattacks before they had consolidated their beachheads. The paratroopers were tasked with demolishing bridges that the enemy could use for a counterstroke against the beachheads, and with securing bridges that the Allied forces might have to pass. They would also clear landing zones for the gliders, most of which would come later carry heavy equipment such as jeeps.

#### British Operations

There British airborne forces comprised one division, the 6th Airborne, which in turn was composed of the 5th and 3rd Parachute Brigades.
D-Day opened with a glider assault by units of the 5th Parachute Brigade against the bridge across the Caen Canal (later renamed the Pegasus Bridge) fifteen minutes after midnight. After briefly exchanging fire with a few sentries, the paratroopers were able to secure the bridge. Shortly after this, another glider assault commenced with the objective of seizing a bridge across the River Orne. Despite a navigational error by a pilot which led to one of the three gliders landing eight miles (13km) east of its intended target, the bridge was secured without further misadventure. These two bridges were the only routes by which the Germans could launch a flank attack at Sword Beach; they were also crucial for the Allied attack on Caen. The heavy cloud cover and poor navigation meant that many of the pathfinders were widely scattered; only one team was dropped correctly. Another was wiped out by RAF Avro Lancasters that had missed their target. Thus, the rest of the brigade was also scattered. The 7th Battalion managed to run into the defenders of the two previously mentioned bridges. After setting up defences, they managed to hold the bridges against a number of German counterattacks. One one occasion, the Germans deployed a tank, which was subsequently destroyed with an anti-tank weapon. On another, the Luftwaffe attempted to bomb the bridge, but the bomb failed to detonate. The 12th and 13th Battalions were tasked with capturing Las Bas de Ranville and Ranville to secure the bridgehead; despite heavy mortar and artillery fire, they completed their mission.
The first unit of the 3rd Parachute Brigade to land was the 9th Battalion. Due to the wide dispersal of the paratroopers, only a quarter gathered at the drop zone when the commander, Lieutenant Colonel Otway, decided to begin the assault on their primary objective, the Merville gun battery. After breaching the defensive perimeter with Bangalore torpedoes, the battalion attacked, but the defenders, who had been alerted to the threat by the explosions, inflicted heavy casualties. Despite a fifty percent casualty rate, they managed to reach the battery and destroy it, although one of the guns was not permanently put out of action. After capturing the village of Le Plein, the battalion was unable to complete any further objectives. The 8th Parachute Battalion was tasked with destroying two bridges at Bures and another at Troarn. With the exception of a brief firefight, their day was anticlimactic, as they found that all three of the bridges that had been tasked with destroying were already demolished. The 1st Canadian Parachute Battalion was tasked with destroying a bridge at Robehomme and another at Varaville. They ran into no resistance on their way to Robehomme, but the sappers tasked with destroying the bridge were not present. They arrived several hours late. Another detachment of the Battalion moved towards Varaville to destroy the bridge and several other objectives, but ran into almost a hundred defenders who had fortified the town. Nevertheless, they managed to persuade the Germans to surrender with concentrated mortar fire.

#### American Operations
### The Landings
#### Naval Bombardment

Prior to the beginning of the actual amphibious landings, there was a naval bombardment beginning at 0550, which targeted not only pillboxes, bunkers etc. on the actual beaches, but also targeted coastal batteries and areas further inland to disrupt German troop movements. Some landing craft were equipped with howitzers and rockets, among other artillery, to act as fire support in conjunction with the larget ships. After the event, the German commander Field Marshal von Rundstedt would comment that the battleships were "quickly mobile, constantly available artillery" and that they "play[ed] an important part in the battle within their range" as they prevented any movement of tanks. However, despite their immense firepower, the impact on the beaches was unimpressive; many bunkers still remained.

#### Sword Beach

The easternmost landing beach was Sword Beach, assaulted by units of the British 3rd Division (and units attached to the division) under the command of Major-General Thomas Rennie. Sword Beach stretched five miles (8km) from Ouistreham to Aubin-sur-Mer, although landings would occur on a sector 1.8 miles (3km) long between Hermanville-sur-Mer and Colleville-sur-Orne (later renamed Collevillle-Montgomery) which was divided into Queen White and Queen Red sectors. The 8th Brigade, 1st Battalion of the South Lancashire Regiment and 2nd Battalion of the East Yorkshire Regiment would form the first wave. Three battalions of the 185th Brigade, supported by the Staffordshire Yeomanry, would march on Caen, while the 9th Brigade was tasked with protecting the right flank of the beach and linking up with the 3rd Canadian Infantry Division landing at Juno Beach. Finally, the 1st Special Service Brigade (i.e. commandos), commanded by Brigadier Simon Fraser, Lord Lovat, would capture Ouistreham and link up with the 6th Airborne paratroopers at Bénouville.
Forming the first wave were a number of tanks and demolition teams. Some of the tanks ran into the path of the landing craft carrying the demolition teams, but quick manoeuvering prevented a potential disaster, and most of the tanks reached the beach safely. The first tanks and troops ashore were immediately greeted with German fire, which was fortunately rather moderate. Ten minutes later, units of the 1st South Lancashire Regiment and 2nd East Yorkshire Regiment landed, along with a number of French commandos attached to Lord Lovat's brigade. The German defenders were suppressed without much trouble, and by 0800 the British troops had advanced beyond the beaches. In another five hours the commandos had linked up with the paratroopers on the Caen Canal and Orne. However, the troops on Sword were unable to link up with the Canadians on Juno.
At 1600, German tank forces and mechanized infantry units from the 21st Panzer Division launched the only German counterattack of any significance on D-Day. After being joined by the 192nd Panzergrenadier Regiment, they managed to reach the beaches between Sword and Juno after four hours, but the division's ninety-eight panzers were stopped by anti-tank weapons, airstrikes and Allied tanks.
At the end of the day, the 3rd Division had landed twenty-nine thousand troops in Normandy at a cost of about 630 casualties, but had failed to join up with the Canadians in Juno and to seize the town of Caen: they were stopped three miles short of it by German panzers. Although Sword and Juno would be joined in a few days, the capture of Caen would finally take place some six weeks behind schedule.

#### Juno Beach

Juno Beach spanned six miles (10km) from Saint-Aubin-sur-Mer to Courseulles-sur-Mer and was just west of Sword Beach. It was assigned to the 3rd Canadian Infantry Division and attached units, under the command of Major-General Rodney Keller. Juno was divided into two main sectors: Mike in the west and Nan in the east. The 7th Canadian Infantry Brigade would assault Mike with the Royal Winnipeg Rifles, The Canadian Scottish Regiment and the 1st Hussars. They were to then take Courseulles and move inland. Nan was assigned to the Regina Rifle Regiment of 7th Brigade, as well as the North Shore Regiment and the Queen's Own Rifles of Canada of the 8th Canadian Infantry Brigade. The 8th Brigade was to capture Bernières and the western edge of Saint-Aubin. By the end of D-Day, the 3rd Division was supposed to have secured the high ground to the west of Caen, the seaside towns of Courseulles, Bernières, Saint-Aubin and Beny-sur-Mer and the Bayeux–Caen railway line.

#### Utah Beach

Behind the advanced assault of airborne soldiers came the primary invasion of three American infantry divisions, the 4th, 29th,and 1st Infantry Divisions on beaches codenamed Utah and Omaha, with two British Divisions and one Canadian on beaches marked Sword, Gold, and Juno. With the placement of infantry on mainland France, the battle of Normandy had begun. A battle that in the end would involve the liberation of France, Belgium, the Netherlands, Italy, Denmark and Norway amongst others and bring the Nazi control of western Europe to an end.