How The Allies Planned Operation Overlord

It's the 6th of June 1944 and nearly 150,000 Allied troops storm Normandy. The infantry fight their way through the rough cold surf to reach the beaches and engage the German defenders up close. Tanks and warships provide heavy fire to blast through concrete imp placements and bunkers. Support troops follow up with the necessary equipment to keep the advance moving. The fighting is fierce, but by the end of D-Day, Allied forces are established on all five beaches and have begun to push inland. The victory of the first day of Operation Overlord was not only won on the beaches and by Allied paratroopers jumping the night before and by the months of bombing of French railways and bridges and the training and preparation that took place to attack the beaches of Normandy, but also work began years earlier with the making of plans of where and when to land troops for the Allied return to France. Also crucial to the success of the landings was stopping the Germans from finding out where the attack would be and stopping German reinforcements from easily reaching Normandy once the landings began. How did all this come together? In this episode, we explore how the Allies planned for D-Day, how the Allies limited the Germans ability to reinforce Normandy, the impact of the French resistance on the landings, and why the Allies chose the 6th of June 1944 as the date to launch Operation Overlord. The role of air power to clear the way in preparation for D-Day is often one of the most underappreciated elements of the invasion. As author Donald Miller wrote in his book, Masters of the Air, the German Vermart would fight a brilliant defensive battle in Normandy, but its fate was almost pre-ordained when Allied air power won the Battle of the Buildup before the invasion began. In order for D-Day to succeed, the invasion area needed to be sealed off so enemy reinforcements could not disrupt the landings or attack the beach head in force in the following weeks. To achieve this goal, the transportation plan was created, which is arguably the most successful bombing campaign of the Second World War. The transportation plan was the culmination of a much larger air operation to support Operation Overlord. On the 14th of June 1942, the British and American combined chiefs of staff issued the point blank directive, which called for a massive strategic bombing campaign against Nazi Germany. The objective of point blank was to win air superiority over Europe by destroying the German Luftvafa. But there were debates about which approach should be used for the campaign. The commander of Royal Air Force Bomber Command, Air Chief Marshall Sir Arthur Harris favored a strategy of area bombing German cities in nighttime raids. This plan was created with the intention of destroying German warf production and urban areas to negatively impact German civilian morale, thus causing a drop in production. Brigadier General Ira Akre, commander of the United States 8th Air Force, the American Strategic Boing Force based in Britain, believed that only precision daylight strikes against key industrial targets could bring the LUvfafa to its knees. Over the next year and a half, both strategies were put to the test. The combined bomber offensive saw the eighth air force bombing by day while bomber command struck at night. With both approaches having mixed results, the eighth air force suffered unsustainable losses during 1943 and failed to the German aircraft industry. But the daytime raids significantly weakened the Luftwaffer's fighter strength. As a consequence, German Minister of Armaments Albert Spare was forced to retool the Reich's war industry while fighter units were recalled from the Eastern Front and Italy to reinforce the home defenses. The RAF's area bombing campaign caused devastating destruction to the broader German economy. Of particular note was the firebombing of Hamburg in summer of 1943 which caused a drop in German civilian morale due to the high level of destruction on the German home front. However, the German populace proved more resilience than Harris expected and did not cause an outright surrender. By early 1944, Allied high command believed neither Harris nor Akre had the right strategy to end the war or support Operation Overlord. General Dwight D. Eisenhower was appointed Supreme Allied Commander in December of 1943, which gave him authority over Operation Overlord. However, this did not give him full authority over Anglo-American air forces, the command of which he saw as absolutely necessary to give the invasion the best chance of success. Eisenhower's friend and commanding general of the US Army Air Forces, General Henry Hap Arnold, supported Eisenhower, having control over all Anglo-American air forces for Overlord. Eisenhower's plan faced opposition from British Prime Minister Winston Churchill, who was reluctant to release British aircraft for use solely related to Overlord. He intended for Britain's bomber command to only support Overlord operations from time to time. Eisenhower spent the next four months pushing for control over the bombers of the strategic air forces. As a way to smooth over the inevitable disagreements, RAF Air Chief Marshall Sir Arthur Tedar was named the deputy commander of Overlord. The leader of the successful air war in the Mediterranean, Tedar's priority was to formulate a plan which would best support Overlord. Air Chief Marshall Sir Trafford Lee Mallalerie, commander of the Allied Expeditionary Air Forces, would execute the plan when the invasion came. Even with the appointment of Tedar, Churchill was still resistant to turn over bomber command to Eisenhower's Control for Overlord. This is John M. Curatollah, senior historian at the National World War II Museum and the author of Armies Afloat: How the Development of Amphibious Operations in Europe helped win World War II. This was the crescendo moment, the most pivotal events not only in the war, but I would argue in the 20th century, but that's a whole another argument. And the air failed to realize that it really kind of came not to blows, but it came to, you know, doctrinal strife between the air component and the LA force commander, i.e. Ike to the point where he has to make the argument, you know, either I get control of all assets or to use his quote, I will simply go home. You know, either I'm the allied force commander or I'm not. >> Churchill, faced with no choice, relented. Ted sought the advice of Sulli Zuckerman, a civilian researcher and anatomy professor. On the 10th of January 1944, Duckerman along with another AEAF planner, Air Commodore Edgar Kingston Mcccluffrey, produced their first draft of what would become the transportation plan. A pragmatist at heart, Zuckermanman argued that the best way to utilize the allies tactical and strategic air assets was to paralyze enemy movement in northern France. The heavy bombers would hit large targets such as railroad marshalling yards and repair shops, while tactical fighter bombers were better suited to strike bridges and locomotives. It was a straightforward, simple strategy intended to prevent enemy reinforcements from reaching Normandy and hinder resupply of the units already there. Furthermore, it would be much safer for the bomber crews to strike targets in France, where enemy air defenses were weaker and the bomber streams would have fighter cover. Eisenhower liked the transportation plan. He was acutely aware that his invasion forces would rely upon vulnerable sea lanes for resupply while the enemy could use the modern French and Belgian railway systems to bring up men and material. It would make the establishment of a firm beach head much easier in the critical first days after landing in Normandy if the air forces could pulverize those transportation networks. Once the allies had landed, they would be in a race against time to build up as much strength as possible before breaking out into the French countryside. If the Vermart was able to bring in enough reinforcements before this buildup was finished, they could keep the Allies bottled up on the beaches indefinitely. The disruption of the logistical network to Normandy was essential to winning this battle. Yet, Zuckermanman's proposal had its detractors. The transportation plan was poorly received by both air chief marshall Harris and General Carl Spatz, the new commanderin-chief of US strategic air forces in Europe who had taken over from Akre. >> One of the big problems that existed was was really internal from the standpoint of the strategic bombing campaign and the combined bomber offensive going [music] deep and going long to affect German industry and more importantly morale from an American standpoint. Army Air Forces wasn't interested in supporting using their 4G engine bombers for the landings in Normandy. And this got to be a contentious point between Ike and Spots who is you know head of US strategic air forces because they see this as a drain on their resources in terms of their primary mission and they really thought that the version of the strategic campaign lessened its effect and failed to realize in my opinion that the D-Day landings were the main effort for the allies. this had to happen. >> Harris stubbornly insisted that bomber command should not be diverted from what he saw as its main task, destroying cities, arguing, "It is clear that the best and indeed the only efficient support which bomber command can give to overlord is the intensification of attacks on suitable industrial centers in Germany. If we attempt to substitute for this process attacks on gun imp placements, beach defenses, communications, or dumps in occupied territory, it would lead directly to disaster. One of Harris's main concerns before the transportation had begun was that his bombers would not be able to hit marshalling yards at night, arguing that the target requirements cannot be fulfilled, and I am compelled to disavow any responsibility for the consequences which their non-fulfillment will entail. In response, the RAF dispatched bomber command to hit six marshalling yards in France as an experiment to see if Harris was right. From the 6th to the 24th of March 1944, the RAF launched 1,26 bombers against these targets. The results were stunning. All six marshalling yards were deemed to be destroyed by post strike reconnaissance. Only six bombers failed to return. Ultimately, Arthur Harris was a realist and by February had privately accepted that he would have no choice but to support Zuckermanman's plan. Ted was satisfied that despite his reservations, Harris would loyally carry out his orders. SP was also unhappy and took a different approach in submitting his own idea. Spans wanted to attack Germany's fuel industry, therefore forcing the Luftvafa to protect it and denying the Vermark the oil it would need to defend Normandy. He believed through the strategy of bombing the extremely vulnerable synthetic oil facilities, he could kill two birds with one stone. The Lufafa would have to come out and fight where it could be destroyed by escorting fighters while much needed oil production was destroyed. SP's plan became known as the oil plan. It was an attractive option because it would only require half of the USAF's bomber strength. The rest could be used in support of Zuckermanman's proposal. Spans's plan had significant backers, including General Arnold and Churchill. Eisenhower carefully considered the arguments for the oil plan, while Tedar and British Air Chief of Staff Charles Portal were skeptical. Ultimately, it was the reputation of bomber command and the eighth air force to exaggerate successes which led to the adoption of the transportation plan over the oil plan. Ted wrote a portal saying, "We've been led up the garden path before in reference to the many war-winning promises that both American and British bomber chiefs had made before. Neither Harris's strategy of area bombing nor the eighth air force's daylight missions had inflicted a mortal blow against the Lufafa. Eisenhower and the rest of his staff could no longer wait for decisive results after so many disappointments. On the 25th of March 1944, Supreme Allied Commander Eisenhower ruled for Zuckermanman. Spatz was disappointed, but his senior target officer, Richard Doy Hughes, later wrote, "If Eisenhower had asked him to drop his bombs in the Arctic Ocean on D-Day, he would have complied." SPATZ was also somewhat satisfied with a commitment from Portal and Eisenhower that the oil plan could be implemented in force after Overlord was a success. To further appease him, a handful of raids against German synthetic oil plants and the Pesh oil fields in Romania were authorized before D-Day. The transportation plan faced opposition from a familiar source. After receiving estimates that the transportation plan would lead to 160,000 civilian casualties, Winston Churchill worried that the campaign would lead to a legacy of hate towards the Allies from the French. After consulting the commander of the free French forces in the United Kingdom, Major General Pierre Koig, he told Churchill, "This is war, and it is to be expected that people will be killed. We would take twice the anticipated loss to be rid of the Germans." On the 15th of April, the final version of the Overlord Air Plan was adopted. The transportation plan was a go. The first official raid of the transportation plan took place on the 6th of March 1944 during the RAF's experimental phase in bombing marshalling yards, but the pace significantly picked up following the 15th of April. Air Marshal Lee Mallalerie had over 20,000 tactical and strategic aircraft which he unleashed on the French transportation network. Over the next two months, Bomber Command along with the US 8th and 9th Air Forces pounded railroad marshalling yards, repair shops, [music] bridges, and moving locomotives in one of history's most devastating displays of aerial bombardment. German military camps, airfields, ammunition dumps, and coastal batteries were also hit hard. In the weeks prior to the actual landings themselves, 84% of the eighth air force's missions are in direct support of the cross channel invasion. >> Although the strategic bombers expended the heaviest ordinance, the tactical air forces did just as much, if not more, damage to the enemy transportation system. The US 9th Air Force's Fighter Command, led by Major General Pete Cassada, ran rampant in the French countryside, hunting for moving trains and their rolling stock. Fighter bombers such as the American P47 Thunderbolt and the British Hawker Typhoon made quick work out of the vulnerable locomotives, often causing spectacular explosions when they targeted the steam engine with rockets or cannon fire. From the 20th to the 28th of May, the RAF's second tactical air force and the US AAF 9th Air Force launched Operation Chattanooga Chuchu, named after the popular wartime song, with the aim of destroying as many locomotives as possible. Over 1,200 aircraft bombed and strafed trains across northern France and Germany, bringing the French railway system to its knees. One of the reports is that that they're so effective in hitting trains that uh engineers stop showing up to work because it's shown to be dangerous work because the RAF and the Army Airore is out there looking for train movement around Belgium, France, and adjacent areas. >> While successful in destroying enemy transportation capabilities, the raid did take a toll on those living near the targets. Approximately 12,000 French and Belgian civilians were killed by the bombing, while thousands more were wounded or made homeless. Although it was almost 10 times fewer casualties than had been predicted by Churchill, it was a steep price to pay to prepare Western Europe for liberation. >> The French people did not blame the allies. Yes, you killed my family or you destroyed my farm, whatever the case may be. But many of them saw that as the price of liberation. >> German propaganda seized upon the heavy losses and French newspapers under German control printed headline stories about the bombing of civilians. A 20th of April headline from a Paris newspaper read, "Thusic evening's raid on Paris and its suburbs supersedes in horror any preceding massacres." The raids aided German propaganda minister Joseph Gerbles, who was determined to force a rift between the Allies by accusing them of terror bombing French and Belgian civilians. The Allies kept a close eye on these developments, hoping to avoid the legacy of hate feared by Churchill. Eisenhower and Lee Mallalerie agreed to drop leaflets over some targets warning civilians to evacuate. But not all urban areas received advanced warning. Pilot John Prior of the RAF's 617 Squadron later wrote about how he tried to avoid civilian casualties as much as possible. It made us see things in a different light, conscious of how accurate we had to be. Any target we missed meant we could be hitting the French people. Despite the heightened concern over accurate bombing along with radio broadcasts and leaflet drops urging civilians to leave, the French and Belgian people would continue to suffer under the bombs. When Operation Overlord finally went ahead on the 6th of June 1944, the transportation plan had been an undeniable success. By D-Day, at least 75% of all the railways within 170 mi of Normandy were unusable. In total, Allied aircraft dropped a total of 71,000 tons of bombs on the French rail network. From the 20th of May to the 5th of June, the final intensive phase of the campaign, tactical fighter bombers destroyed at least 475 locomotives and cut the French rail system at 150 different points. By the last week of May, nearly every single rail crossing over the river Sen had been closed. Losses were astoundingly light when compared to the first years of the air war. Of the 21,949 sorties dispatched to bomb transportation targets from the 9th of February to D-Day, only 51 aircraft were shot down and another 29 damaged. This was a loss rate of [music] 0.2%. The air campaign included a measure of deception to aid in the success of Operation Overlord to confuse the enemy as to where the invasion would come. For every time Normandy was bombed, the Pardala area would be hit twice. It also succeeded in curtailing construction of the Atlantic Wall, Germany's extensive network of coastal defenses and fortifications. Without any large shipments of good quality steel or concrete, the German tote organization was forced to use inferior material while other construction projects were abandoned entirely. At least 49 coastal batteries were hit while the destruction of radar installations, wireless telegraphs, and navigation stations paralyzed enemy communications. The constant bombing of the railway network forced 18,000 men of the tort organization to cease construction of new coastal defenses and instead repair the damaged marshalling yards. When the Allies landed in Normandy, they were not able to break out of their beach head immediately, but they had decisively won the Battle of the Buildup. The German leadership would certainly agree with this assessment. Commanderin-chief of the Western Front, Field Marshall Ged Von Runstead, later told interrogators that the invasion only succeeded due to our inability to bring up our reserves at the proper time. The commander of the German army high command, Bilhelm Kaisle, gave a similar response. Nobody can ever prove to me that we would not have repelled the invasion had not the superiority of the enemy air force in bombers and fighters made it impossible to throw these divisions into the fight. When taking into consideration the mission objective and outcome, the transportation plan can be considered one of the most successful bombing campaigns of the Second World War. In terms of of combat, that's good enough. You weren't able to reinforce during those precious few weeks where the allies only had a tow hold. And so the transportation plan in my opinion works good enough. When you look at the transportation plan, you know, in its aggregate, I don't think it necessarily has the effect they expected it to do. But I will also make the argument that it works good enough and that it provides enough tactical delay. It provides enough problems for the Germans that they have to really uh revise some of their plans that they have. Uh with regard to that >> the transportation plan did not just rely on allied aircraft to the logistic network that the Germans would need to reinforce the Normandy beaches. The French resistance played a role not only in hindering German movement throughout France but also in aiding the landings themselves. The top secret codereing project at Bletchley Park known as Ultra gave the Allies a distinct advantage over their adversaries. They were able to break German codes and were therefore able to intercept German communications. However, not everything about the enemy could be learned through Ultra, which only referred to decryptions of German radio and teleprinter communications. The Allied intelligence services needed help from those in occupied Europe to ensure that D-Day would be successful. Following the German victory in the Battle of France in 1940, much of the country came under German occupation while the puppet Vichi regime controlled the rest. But German and Vichi political control did not mean full support from the French population. Resistance against the German occupiers began immediately following the 1940 armistice and only intensified throughout the war. The French resistance played a key role in the preparations for the Normandy landings. The various resistance groups in Normandy, although not one homogeneous group, provided critical intelligence on German defensive positions and sabotaged infrastructure to prevent the enemy from moving reinforcements in. >> In the first few months of the transportation plan, the French [music] resistance will knock out about 800 locomotives, whereas the RAF and the Air Force knocks out like 400. But after the transportation plan gets in [music] place, those numbers will reverse. and the army airore will be taking out more locomotives than the French resistance. But this is some of the things the French are doing. >> French resistance groups received much aid from the British Special Operations Executive or S SOE based in the United Kingdom. SOE used three methods of communicating [music] with the resistance radio, aircraft, and pigeons. Specialized radio transmitters were often smuggled into France and used to coordinate actions between SOE and the various resistance groups. These would sometimes be brought into the occupied country by sea, but mostly by air. Aircraft such as the Westlander would leave southern England and arrive in France at night to drop supplies or land at makeshift air strips, bringing in people and equipment. The US8th Air Force also played a role here through the so-called carpet bagger missions. The American 801st Bombardment Group flew modified B-24 Liberators which could drop larger amounts of supplies as well as undercover agents. By June of 1944, the Allies flew over 850 supply missions every month to support the French resistance. However, these means of communication were not always available or reliable. Weather would often prevent missions from taking place, and downed pilots ran the risk of being captured and tortured by the Gestapo. Furthermore, the Gestapo along with the ABV, German military intelligence, would often listen in on radio communications. The Advare did this through Operation Donor, a special program in which specialized directionfinding units intercepted resistance radio messages and then hunted them down with the help of a centralized control station. This forced resistance radio teams to constantly move their transmitters to avoid detection. But at least 10% of these resistance teams were discovered by German intelligence. When conditions prevented communication by aircraft or radio, homing pigeons were employed instead. Throughout the war, the British National Pigeon Service bred and raised 200,000 pigeons, which were remarkably good at their jobs. One particular pigeon traveled 1,090 mi from Gibralta to London in 28 days, a record distance for a pigeon in the Second World War. Pigeons were also simple to use. A message would be tied to their leg and the animal, when released, would return to its roost. One of the pigeon's most important functions was to facilitate communication between Allied intelligence and the French resistance. Beginning in 1941, British intelligence began dropping homing pigeon containers across Western Europe. Drawings and architectural plans for the Atlantic wall defenses were sent back to London via Pigeon, where Allied intelligence would match these drawings with reconnaissance photographs. Also, small questionnaires inquiring about German defenses and local forces were included with the containers for civilians in occupied countries to fill out. These pigeons often fell into German hands and a counter intelligence effort began as Abbe officers would fill out the questionnaires with false information. From 1942 to 1944, 16,54 pigeons were dropped into occupied Europe and 1,842 were returned to the United Kingdom. It is unknown to this day how many returned with useful information versus bogus information. Unfortunately, the Germans figured out the importance of homing pigeons to the resistance. >> They would employ hawks to go after the pigeons or they would also issue shotguns to uh some of the troops too to take down any carrier pigeons that might be flying around. >> One of the pigeons shot by the Germans could have made a difference had it reached Britain. Failing to spot the 352nd Infantry Division had major consequences for the landings. The division was one of the few mobile Vermont units in Normandy and had been transferred from their staging area around the town of Sanlow to the Normandy coast 3 months prior to the invasion. The local resistance was well aware of this movement and sent out several homing pigeons to warn the Allies. However, German anti-pigeon patrols and the arrest of several resistance members doomed this effort. Despite the difficulties in using birds to carry vital information, the use of pigeons for planning D-Day is one of the more unheralded episodes of the Second World War. How the French resistance gained the information about the defenses in Normandy was a complicated and risky process that put many lives at stake. The resistance cells in Normandy were loosely organized and their contribution to the invasion varied. According to historian Steven Zaloga, some groups specialized in espionage, others in political agitation and some in direct actions, military raiding. The alliance network was one of the most active. It was led by Lust. Alliance had three cells in Normandy which operated in Verville Shumeare on the future Omaha Beach, Porto Basan at Gold Beach and the city of Bayer less than 10 mi inland of the landing beaches. Throughout the war around 20 civilians assisted the Alliance resistance cell and an estimated 180 individuals helped the resistance in Normandy. Despite the German occupation forces sealing off the coast to civilians, other than to those who lived there and those delivering mail, vital intelligence was still gathered about the beach defenses. The alliance group was able to gain access to the restricted coastal area due to many of its members being postmen enabling them to scout the beach defenses. Also, French construction firms did most of the work on the Atlantic Wall, and French Moroccan workers passed on vital information to the resistance. The Alliance Cell scouted most of the major German fortifications on the western end of Normandy, including the artillery batteries at Maisy, Longare, and Point Duh Hawk, along with the defenses on Omaha Beach itself. French laborers constructing the defenses also provided valuable information to the resistance and carried out small acts of sabotage. As one example, French workers would often pour quick lime into cement mixtures which would make the German concrete fortifications brittle and prone to collapse. Alliance worked with another network loan civil military or OCM based in Bayer. The OCM focused primarily on intelligence gathering as their resources were too limited to undertake military operations. The network gathered information concerning German equipment, fuel depots, the size and origin of units, the locations of minefields, and details of fortifications. The information gathered was turned into maps for the allies to use. Gon Merkadair, a former soldier in the foreign legion, was a member of the OCM. As a former professional cyclist, he was able to get permission from the Germans to cycle around Normandy obstinately for training purposes, but he was really gathering intelligence and passing messages. As he continued to work with the OCM, Meadair was asked to organize the entire internal network in the Bessan region, particularly in Corsul, Porton, Bessan, Grant, Messi, Aramash, and Iseni. One of Meadair's responsibilities was to take the information gathered and make extremely detailed maps. This program was cenamed Bigot to guide the Allied invaders after landing. In October of 1943, Robert Deon, the head of the OCM network, left Bayer under the risk of arrest by the Gestapo. From December 1943 onward, there were no more new recruits as the danger was too great. The Gestapo was looking for a certain individual cenamed Messier, who was none other than Guill Meade. He nevertheless continued his activities and was never caught by the Gestapo. He met Allied troops when Bayer was liberated. Disaster struck the Alliance cell on the 14th of March 1944 when a liaison officer from the cell was arrested by the Gestapo in Paris. German counter intelligence quickly zeroed in on the resistance in Normandy and began rounding up suspected underground members. The leader of the alliance cell in Verville, Desiree Lumierre, was aware that the resistance was now living off borrowed time, and his small group increased the tempo of their actions. More pigeons were sent out detailing the buildup of German forces in the area, including the arrival of the 352nd Infantry Division in the Omaha Beach sector. According to author Steven Zoga, at least one pigeon detailing the move of the 352nd Infantry Division may have made it to London. On the 3rd of June 1944, a report possibly containing information from the French resistance delivered by Pigeon gave a warning that the 352nd division had likely been moved to the coast to reinforce the divisions already manning the defenses. Questions over the validity of the source of the information may have limited the circulation to higher commanders. Further evidence suggests that even if senior commanders had known that the 352nd division had been discovered in the Omaha Beach sector, it was far too late to make any major changes to the plan. The forward inertia of planning ensured that the attack would have to go ahead as scheduled. On the 5th of May 1944, Lumiere and his group were arrested and imprisoned in the local Gestapo headquarters. They were among the 73 prisoners murdered at the K prison on the 6th of June 1944. Alliance members Antoine Duche, Robert Dwin, G Sol, and George Tomin were also murdered. Osia members Henri Liar and his son Alexis Liar were also killed. Some of the executed were arrested after a locomotive was derailed on the 1st of May 1944. The youngest victim of the massacre, Colbear Marie, was only 17 years old. He wrote a plea on a handkerchief in his own blood for his mother to save him. Although the German counter inelligence efforts were able to round up many members of the resistance in Normandy and had success in stopping pigeons from reaching Britain, plenty of the information made it to Allied intelligence to influence the events on D-Day. The architectural drawings which made it across the channel were extremely detailed and Allies planners were able to mark individual obstacles and fortifications with pinpoint accuracy. Although reconnaissance flights were useful in locating enemy defenses, they could not determine the contents of bunkers and blockhouses, nor the thickness of concrete. It was the drawing smuggled out of France which gave the planners an idea of the thickness of certain concrete bunkers, which ones contained machine guns or anti-tank guns, and how many men would be inside. The French resistance in Normandy suffered many losses by the time the allies landed, but they had provided essential information on the state of German defenses and the units defending the coastline. Their sacrifice ensures the allies had the best possible intelligence on enemy fortifications and certainly saved many lives on D-Day. the resistance really does kind of provide some of that grassroots harassment, but more importantly the intelligence piece on that. But one of the things that's really significant when you get to the Normandy invasion is that the resistance can provide all kinds of really useful information about German dispositions, strength, locations, construction, infrastructure. you know what the Germans have laid here and built in this part of France to aid the allies in terms of targeting and that is significant. >> But despite all preparations, training and pre-invasion attacks on the infrastructure in France, there was one thing the Allies could not control, the weather. Almost nothing was left a chance as the allies embarked upon the largest amphibious invasion in history. The work of the French resistance and the allied air forces with the transportation plan allowed the allies to control many of the factors in the upcoming assault. There was however one key factor they could do nothing about the weather. The weather on the 6th of June was far from ideal. The landing craft and duplex drive swimming tanks were tossed around by rough seas, many sinking before they reached the shore. To make matters worse, the overcast weather limited close air support and hampered the pre-invasion aerial bombardment. The Allies managed to establish a firm beach head by the end of D-Day despite these difficulties. But why did they choose to land in these subpar conditions? To understand why the allies went ahead on the 6th of June, many crucial decisions were made prior to the invasion. Planning for Operation Overlord began following the Casablanca Conference in January of 1943. Allied leaders confirmed their commitment to a cross channel invasion of German occupied France, but clashed on the timing and strategy. In March, Lieutenant General Frederick Morgan of the British Army was assigned as Chief of Staff Supreme Allied Commander or COSAC. He drafted the initial invasion plan with the expectation that the operation would commence on the 1st of May 1944. Morgan's initial plan formed the basis for the eventual invasion. It identified Normandy as the primary landing point, called for a massive deception operation, and advocated for the use of artificial harbors along with airborne landings. However, Supreme Allies Commander, General Dwight Eisenhower, and General Bernard Montgomery, commander-in-chief of Allied ground forces, believed not enough men were committed to the initial assault. Morgan's plan called for only three seaborn divisions and two airborne brigades to make the attack. Eisenhower and Montgomery revised the plan to six seaborn divisions and three airborne divisions in order to ensure proper weight of numbers and firepower. However, the decision forced the delay of overlord by a month in order to requisition more landing craft. This would not have been a problem except May of 1944 had been a month of perfect weather conditions. Early June would not be the same. The date for the invasion was set for the 5th of June. With everything in place to launch Operation Neptune, the amphibious assault portion of Overlord, the only variable left was the [music] weather. General Morgan and the rest of the Allied planners had set strict conditions on which days the invasion could be launched. First, a full moon to allow for illumination at night for aircraft, especially the vital airborne drops. This would also provide the highest and lowest possible tides. Second, low winds and calm seas to make it easier for the landing craft and duplex drive tanks to wade ashore. Third, clear skies devoid of cloud cover to allow Allied aircraft to provide support to the landings. Fourth, 17 hours of daylight to allow as many troops to come ashore during the day. And fifth, an inshore wind to blow smoke away from the areas targeted by the pre-invasion naval and aerial bombardment. Mother nature gets a vote not only in terms of the title variations but also in terms of larger meteorological effects. Wind which will affect seaate rain which of course will affect visibility. Same thing with cloud ceilings and those kind of things specifically with regard to targeting. The man responsible for determining whether these conditions could be met was Group Captain James Stag of the Royal Air Force, General Eisenhower's Chief Meteorological Officer. Eisenhower described Stag as a daer but canny Scott, who fully understood the responsibilities he had been given. Stag was not a meteorologist by trade, nor a soldier. He had originally worked as a geoysicist before the war and was given the title group captain in the RAF's Volunteer Reserve to lend him the necessary military authority. From his post at Sodic House, Supreme Headquarters Allied Expeditionary Force, Stag spent months pouring over meteorological data sent to him from various weather posts located around the Atlantic Ocean. But here's a time when you only really have weather observations and you have to take these weather observations in aggregate and put together this puzzle piece of what the weather patterns look like. >> On the 1st of June, general imbarcation for the invasion began with men and material being loaded onto transport while Royal Navy and US Navy warships prepared to sorty from Scapper Flow in the Ornne Islands in the north of Scotland. Throughout April and May, Eisenhower had been continually testing Stag and his weather team by demanding three-day forecasts, which were then checked against reality. So far, Stag and his men had passed these tests. But on the eve of D-Day, he began to receive conflicting data. Deep depressions had been detected forming in the North Atlantic, which would indicate rough seas, but the different American and British meteorological departments disagreed on what this meant for the invasion. On the afternoon of the 1st of June, Stag informed Major General Harold Bull, Eisenhower's assistant chief of staff, that the situation is difficult and complex. With everyone in southern England on edge, Bull lost his temper. For heaven's sake, Stag, get it sorted out by tomorrow morning before you come to the Supreme Commander Conference. General Eisenhower is a very worried man. The decision on whether to proceed with the invasion rested solely upon Eisenhower's shoulders. The Supreme Commander had three basic options. Launch the operation, launch after a 24-hour provisional postponement, or cancel and await developments after 2 weeks. The 24-hour postponement was considered by many to be the riskiest option, as this meant that the ships already headed for Normandy would have to return to port. The warships leaving Scappa Flow would have to do the same. But this could only be done once without needing to refuel. Above all else, the chances of the invasion fleet being spotted by enemy reconnaissance aircraft or patrol ships would increase exponentially. Eisenhower was concerned that a postponement would cause the soldiers in the first waves to lose their fighting edge. He did not want them stuck aboard the cramped transport ships for too long. At the 10:00 a.m. morning conference on the 2nd of June, Stag was forced to repeat that he did not have any new developments on the weather, much to the chagrin of Eisenhower and his staff. The decision to postpone or cancel the invasion had to be made by the following evening or it would be too late to recall the ships already on route to Normandy. Stag once again canvased his staff and once again found a deadlocked consensus. The British meteorological teams were nervous about the prospect of storms. While the Americans were optimistic that the operation could proceed. Snag later remembered, "Had it not been fraught with such potential tragedy, the whole business was ridiculous. In less than half an hour, I was expected to present to General Eisenhower an agreed forecast for the next 5 days, which covered the time of the launching of the greatest military operation ever mounted. No two of the expert participants in the discussion could agree on the likely weather, even for the next 24 hours. At the 9:30 p.m. conference on the 2nd of June, Eisenhower began the proceedings with, "Well, Stag, what have you got for us this time?" Trusting his gut, Stag responded, "The whole situation from the British Isles to Newf Finland has been transformed in recent days and is now potentially full of menace." He proceeded to describe a bleak picture of the weather for the 4th to the 5th of June. The officers present could not believe this forecast, some glancing out of the window at the picture perfect day. you're just a group captain and here are these guys that are, you know, field marshals and generals that have differing opinions and to stick to your gun in terms of of the human dimension piece of this, you know, and I think that kind of speaks to the group captain's, you know, character itself, but to go with what he thinks is right, not what the room temperature is, if you get my drift on that. When asked by Eisenhower if the situation would improve on the 6th or 7th of June, Stag responded plainly, "If I answered that, sir, I would be guessing, not behaving as your meteorological adviser." The Supreme Commander adjourned the conference without making a decision, waiting until the following day for more data. Stag's intuition proved to be correct. On the morning of the 3rd of June, barometers began to fall across the North Atlantic, while the weather posts in Ireland reported gale force winds and low cloud cover. Armed with this knowledge, he recommended Eisenhower postpone the invasion. With a heavy heart, the order went out for a provisional postponement. The warships and convoys were turned around while destroyers were sent out to retrieve any landing craft without radios and shepherd them back to port. Operation Neptune rested on a knife's edge. If the weather did not improve in the next 48 hours, the invasion would have to be pushed back 2 weeks when the tidal conditions would be right again. Morale and secrecy were in jeopardy after so much careful planning. Stag awoke on the morning of the 4th of June to another beautiful day with no wind. The horrified chief meteorological officer wondered if he had forecast wrong and could not face his fellow officers at breakfast. However, he felt some measure of relief when the predicted storm rolled in later in the afternoon. battering Sodic House with rain and high winds. Despite the suddenly wretched weather, Stag soon received welcome news. At the 9:30 p.m. conference, he faced the leadership as a new man. Gentlemen, since I presented the forecast last evening, some rapid and unexpected developments have occurred over the North Atlantic. there would be a gap in the bad weather on the evening of the 5th of June lasting for up to 36 hours. Stag cautioned Eisenhower that the weather would not be ideal but it would be good enough for an amphibious landing. A spirited discussion followed. Admiral Bertran Ramsay, the naval commander of the Allied Expeditionary Force, made it clear that they had to decide in the next 30 minutes if the invasion would go ahead or else his warships would [music] have to be recalled again. Air Chief Marshall Sir Trafford Lee Mallalerie, the air commanderin-chief, expressed concern that the bombers and fighter bombers would have bad visibility and proposed cancellation. Finally, Eisenhower turned to Montgomery and asked, "Do you see any reason why we should not go on Tuesday?" Montgomery responded immediately, "No, I would say go." Eisenhower pondered for a second before saying, "I'm quite positive we must give the order. I don't like it, but there it is. I don't see how we can possibly do anything else." He ended the conference and ordered Stag to report again at 4:15 a.m. the next morning to confirm the weather. The chief meteorologist Julie returned early on the morning of the 5th of June with a confident report. The weather forecast had held and his recommendation stood. With wind and rain continuing to batter Southern House, Eisenhower once again pulled his staff. Montgomery was impatient to get on with it while Ramsay deferred to Lee Mallalerie. The air chief was still uneasy but finally said he was willing to proceed. The Supreme Commander smiled and confirmed his decision. Okay, let's go. The room erupted into cheering and the aids at hand quickly dashed out of Savic house to relay the orders. A relieved Stag returned to his bedroom to grab some muchneeded sleep. Months prior, General Morgan had teased him by saying, "Good luck, Stag. May all your depressions be nice little ones, but remember, we'll string you up from the nearest lampost if you don't read the omens right." The weather prediction held and Operation Neptune went ahead as planned. As predicted by the meteorological team, the conditions were not ideal, but were good enough for the invasion of France to be a success. Stag and his staff were proven right in more ways than one. Had Eisenhower canceled the landings and gone ahead 2 weeks later between the 18th and 22nd of June, they would have run into the worst storm in 40 years along the Normandy coast. The surge and wind were so powerful that it destroyed one of the two artificial harbors supporting the invasion. One member of Stag's staff, New Zealander Lieutenant Commander Lawrence Hogbin, later recalled, "On the 17th of June, all six of us produced a forecast for the 19th for almost perfect conditions, but the invasion would have been a complete catastrophe." The images conjured up by D-Day are often the fighting on the landing beaches and beyond. Allied soldiers struggling through surf, the bloodshed, the glider assault on Pegasus Bridge, and the airborne landings. The invasion succeeded because of the courage of young men, but also because of months of planning, trial, and hard choices. >> You know, I don't know if it's luck. I think you have competent people in positions of power who make right decisions. When I think that's indicative of the allies throughout the war, not that it always worked. That's not what I'm saying. But I think in the aggregate and I think Stag is one of those guys. >> The transportation plan crippled German mobility over the course of three months. The French resistance despite terrible losses delivered vital intelligence which saved the lives of Allied soldiers. Group Captain Stag's brave weather forecast under pressure gave Eisenhower the narrowest of windows to launch the invasion. Together, these elements remind us that victory in Normandy was never inevitable. It was engineered through coordination, debate, compromise, and no small amount of luck. More than 80 years later, the planning for Overlord still offers lessons. that air power can be an essential element in deciding a ground campaign, that intelligence often comes from unexpected places, and that even the most powerful leaders must trust specialists when the stakes are highest. The assault on the beaches of Normandy tell the story of sacrifice, but the planning behind the assault tells the story of foresight. Without that foresight, the 6th of June 1944 would not be remembered as a great victory for the Allies and the beginning of the end of the war for Nazi Germany. Thanks again to John Curatollah, senior historian at the National World War II Museum in New Orleans in Louisiana and author of Armies Afloat: How the Development of Amphibious Operations in Europe helped win World War II.