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In this special standalone episode, host Tripp Collins steps out of the standard author interview format to share a story from his own field: ocean wave science. Learn how a 1913 storm in Casablanca, WWII Higgins landing craft, and two Scripps oceanographers led to the mathematical breakthroughs in surf forecasting that made the D-Day landings possible. Key Highlights:
If you prefer a visual experience, you can watch the video version on YouTube with historical charts, diagrams, and photos. Chapters: 00:00:00 - Introduction to this special episode on wave science history 00:00:49 - Context on YouTube visuals and inspiration from the movie Pressure 00:02:37 - The practical power of ocean wave prediction for ports, warfare, and surfing 00:03:29 - The 1913 Casablanca swell and early pressure chart analysis 00:05:16 - The Azores field office in 1922 and the first operational swell forecast 00:06:41 - Why early local forecasting methods failed when applied elsewhere 00:07:55 - WWII amphibious landings and the need for universal wave physics 00:09:08 - Early British empirical rules developed by Claude Suthens 00:10:20 - Walter Munk's journey from Austrian skier to Scripps oceanographer 00:12:51 - Army service and Munk's return to Scripps under Harald Sverdrup 00:14:17 - Operation Torch and Higgins boats: Floating shoeboxes in heavy seas 00:16:44 - Spotting the wave height discrepancy for the North Africa invasion 00:18:22 - Building a mathematical model for wind wave growth from weather maps 00:20:12 - Standardizing Significant Wave Height with landing craft coxswains 00:21:49 - Operation Torch in November 1942: Forecasting Casablanca surf 00:23:49 - Training weather officers at Scripps for Operation Neptune 00:24:46 - Balancing tides, moon phases, and surf limits for D-Day 00:26:41 - Maureen Flavin Sweeney's barometric warning and Eisenhower's 24-hour delay 00:28:25 - June 6, 1944: 133,000 Allied troops land on Normandy beaches 00:30:22 - The unpredicted storm 13 days after D-Day and the timing of the invasion window Full Unabridged VersionAccurate prediction is powerful. In the case of ocean waves, the power to predict wave height, period, and direction at some future time at any location could be an operational advantage when running a port, it could be a tactical advantage in wartime, and it could put you in position to get the cover shot of Surfer Magazine when you score a major swell. However, it was a long and twisty road building up the requisite intimacy with the physics before any kind of predictive power was achieved, and it started just after the turn of the 20th century. In 1913, the port of Casablanca was rocked by a massive swell. The French-occupied city was growing rapidly from a population of 12,000 in 1907 to 110,000 in 1921, and was one of the most important ports in the region. The damaging swell was not an isolated event, but the culmination of a series of swells that wrecked small craft and rendered the harbor inoperable for months. While a calamity as such was understood to be a natural act of God, the French government invested in the study of the swell events with the aim of reducing future harm. A man named Gain was assigned to this duty. He examined weather charts, which were synoptic scale maps of atmospheric pressure at sea level over the North Atlantic. The charts showed broad areas of high pressure and low pressure. Wind rushes from areas of high pressure into areas of low pressure, like air rushing out of a pressurized balloon, and the deeper the low, the faster the wind speed. Gain was able to link the appearance of low pressure systems on synoptic weather maps of the North Atlantic to swell events, perhaps the first to show that swell arriving in northwestern Africa originated from the North Atlantic. Further, he showed that different pressure patterns resulted in swells of different character. This information was the key to unlocking a warning system. The swell formed offshore, far to the west, and propagated towards the coast but would first encounter the Azores, a small island chain about 1,500 km west of Casablanca. Since the swell tended to arrive from the west, the idea was that the swell observed in the Azores would be the same that later impacted Casablanca. Indeed, this was the case. They set up a field office to make visual wave observations in the Azores. Swell observed in the Azores would then take 1–2 days to reach the coast of North Africa, time in which the office could warn Casablanca via telegraph of an impending event. Thus began the world's first operational swell forecast, and the year was 1922. A researcher summarized the state-of-the-art in 1943, “...with some experience one may become proficient in forecasting the phenomena, at least at Casablanca.” And that was the catch, it was a kind of empiricism that couldn’t be applied elsewhere. For example, even though Bermuda is 1,500 km to the east of the port of Charleston, South Carolina, observing swell in Bermuda is not helpful for predicting swell in Charleston. This is because low pressure systems tend to form off the U.S. eastern seaboard and move east. A storm in Charleston might later impact Bermuda, not the other way around. Therefore, the Azores-to-Casablanca forecast worked because of the typical atmospheric patterns in the North Atlantic. In the mid-latitudes, the prevalent flow is to the east which storms tend to follow, creating swell that also travels eastward. Yet, a universal method for surf height prediction was just what was needed as amphibious landings became an increasingly important tactical approach of the Allied Forces during World War II. To accomplish this task, our understanding in three areas needed significant advancement in (1) how waves develop under the influence of wind, (2) how waves propagate, and (3) how they transform over bathymetry. There were some hints about how waves develop. The Beaufort Force Scale was in wide use, which roughly gives a wave height as a function of wind speed, and by the turn of the 20th century scholars knew that space and time might also be important factors for growth of wave heights. On the latter two aspects Captain Charles Bates, a meteorological officer during WW2, later recalled the state-of-the-art leading up to the war “[contemporary] research did not adequately describe how a wave train decayed within distance from its generating area and then, in shallow water, changed into a plunging breaker.” In Great Britain, Instructor Commander Claude Suthons was assigned the task of transforming sparse data into rule of thumb. He studied the existing literature and, working by himself, was able to develop some relationships between the effective wave height data and the wind speed. Suthons produced graphs that linked a fetch and duration to a wave height and period. He also estimated a decay rate over space. It was an empirical solution, not a global understanding of how the systems work, but perhaps it could be calibrated for different locations. Under time constraints, he arrived at a practical, engineering-style solution. He characterized the behavior of a system using available observations and hoped nothing happened outside its scope. The American effort to predict surf was led by two European immigrants. Enter Walter Munk. As a young man, Munk’s primary interest was in outdoor sports, skiing in particular, which there was no shortage of opportunity for in his native Austria. His well-to-do family sent him to prep school in New York to distance him from the sport, in hopes he would fall in line and join the family banking business. Munk tried and failed as a banker in New York, and made his way to CalTech in Pasadena, CA to pursue a degree in physics. In the summer of 1939, the 21-year-old Munk followed a girlfriend to the serene coastal village of La Jolla, just north of San Diego. To afford his stay, he picked up a summer job at the Scripps Institution of Oceanography under director Harold Sverdrup, a 51-year-old Norwegian explorer and pioneering oceanographer. The inciting romance faded, but Munk became smitten with the ocean. Munk asked Sverdrup the following summer if, after graduating from Caltech, he could become a PhD student with him at Scripps. Sverdrup hesitated, saying he didn’t know of a single position in oceanography that would open up within the next twelve years. In the 1940s, Oceanographic institutes in America numbered three, Scripps in La Jolla, Woods Hole in Massachusetts, and University of Washington in Seattle, and the positions were so few that you had to wait for someone to die to create an opportunity. Sverdrup wasn’t just trying to dissuade an overenthusiastic youth that he didn’t think would make the cut, he was genuinely concerned that there would be little in the way of prospects for this young man’s future. Munk, for his part, was unfazed. Without hesitation, he replied, “I’ll take it”. These were early days of oceanography, and Munk liked to say that for some years he made up the whole of the student body at Scripps. There is perhaps no more idyllic place in America than La Jolla, and Scripps with its beachfront campus was a paradise. Munk had hit the jackpot, except all was not well back home in Europe. Austria had recently been invaded by Nazi Germany. Munk faced a difficult choice, but was compelled to volunteer for the U.S. Army and apply for American citizenship, his oceanographic studies deferred. While his oceanographic compatriots joined the naval reserves, Munk joined the Ski Battalion in Seattle, Washington, for reasons altogether obvious. After serving 18 months and growing frustrated with the lack of action, Munk was discharged at the behest of Sverdrup so that he could return to Scripps. German submarines were picking off U.S. merchant ships seemingly at will. Another Scripps professor, and future director, Roger Revelle was organizing the anti-submarine warfare effort and thought Munk could help. Munk barely had time to unpack his bags upon arrival to Scripps when Japan attacked Pearl Harbor, and just like that the U.S. had fully entered the fray and discharges from service were no longer possible. Had Munk still been with his ski company he would have deployed to Papua New Guinea, where the ability to ski was not an advantage, and according to Munk his company was “virtually wiped out”. At the very least, his deployment would have set his life on an alternative if not disastrous path, but as it was, Munk found himself in the company of oceanographers when the U.S. entered the war, and this may have made all the difference. Under an anti-submarine research detail, Munk was whisked off to the Pentagon. At the Pentagon, Munk learned about the plans for Operation TORCH, which was to be the first major offensive by the Allied Forces. The plan involved making amphibious landings in North Africa, with the newly built “Landing Craft, Vehicle, Personnel” boat, often called the Higgins boat after its designer, New Orleans based boat builder Andrew Higgins. The Higgins Boats were rectangular, rather like a miniature barge. They were transport vessels built for carrying loads of people and equipment to the shore from deeper water. The bow of a Higgins Boat articulates so that upon beaching, the bow is lowered and troops and equipment spill forth. That is, if Higgins Boat first manages to navigate safely to the beach. The beaching of the vessel required shallow draft and a relatively flat bottom, which was fine for heavy loads but was a poor design for navigating waves. The much larger “Landing Ship, Tank” actually had tanks that could flood, increasing the draft and improving handling in heavy seas. The Higgins Boat had no such mechanism for increasing stability. Captain Bates was later to describe them as such “...[the] blunt pop-open bows [of the Higgins Boat] made them extremely sensitive to wave action. To a large degree they looked like and behaved like floating shoe boxes.” Munk flew down to the Carolinas where the US Military was field-testing the Higgins Boats and was able to see them in action. Munk learned some key performance heuristics: the Higgins Boat operated well when the seas were 3–5 feet high. If, however, the waves exceeded 5 ft, the Higgins Boat had a tendency to broach, unintentionally veering 90 degrees. The broadside of the Higgins Boat would become exposed to the surf, and once perpendicular to the oncoming waves, breakers would crash over the side rail and flood the interior. The boats would continue to fill with seawater, with wave after wave breaking over the side, sinking them further. It was only a matter of time until the vessel foundered, spelling disaster for the men and equipment onboard. In short, Higgins Boats were an asset on calm days and a liability in rougher seas. Because of this, they did not conduct training exercises in seas greater than five feet. A question formed in Munk’s mind: how does the wave climate at the test site in Carolina compare to that of northwest Africa? Gathering what information was available, it turned out that while 5 ft waves were rare in South Carolina, 6 ft was the average winter wave height for the northwest coast of Africa, and wave height often exceeded 6 ft. Munk thought this was a catastrophe in the making: what would happen to the soldiers in these high seas? When the alarmed young scientist brought the deadly discrepancy to the attention of his superiors, he was casually dismissed, “They’ve probably thought of that” meaning mind your business, do what you are told, and don’t ask questions. Who was “They”? It is possible “they” referred to the British prediction method, but Munk came to believe that there simply was no “they”. Munk, still a student with low rank and non-existent reputation, was not in a position to challenge authority. All the same, he couldn’t shake the thought that the issue of large waves and the Higgins Boat was important, maybe crucial. For amphibious landings to succeed, they would need to know the wave height in advance. If they had wave information in advance of an operation, they could make “go” or “no-go” decisions that would improve the chances of a successful mission. He must have thought he could do it, that he could figure out the problem of predicting waves, because he set about doing it without explicit permission. In the modern world where the 10-day forecast for any beach on Earth is a click away, it is difficult to imagine but Munk had next to nothing to go off of. He would not have known about Suthons's method, because it was highly classified. Later publications suggest he knew of the Casablanca swell forecast because he used some of the observations from the Azores, but he may not have been aware of how the method worked because the details were published in French. Otherwise, little was known about wind wave development. Mariners might know the local signs of bad weather. Those unfortunate enough to meet a storm at sea would note the appearance of the sky and clouds or simply watch the glass barometer. As the mercury dropped, it signaled that the winds and the seas were picking up. Similarly, folks at the coast would simply look at the surf. What are the current conditions? Is it safe to launch a boat and fish for the day? If so, let’s hope the conditions don’t take a turn for the worse while we are out there. With no method for predicting waves and very little understanding about how seas developed in storms, Munk would have to invent the necessary implements whole cloth. And like the Casablanca office, Munk started with synoptic weather charts. Any synoptic scale wave prediction would need to start with these maps, as these were the only accessible large scale data. In this way, Munk could define areas where he knew winds would be blowing. He knew there had to be some relationship between growth of waves and areas of low pressure on the maps. After months of careful study, he was growing frustrated with his slow progress and his inability to influence the ranking officers. Munk reached out for help. He called his friend and mentor Harold Sverdrup, who dropped everything, took the next flight from San Diego to Washington D.C., and joined Munk at the Pentagon for 3 months of intense work. With Sverdrup by his side, the team made significant progress. Harold Sverdrup had time to contribute because secretive security concerns, initiated by disgruntled Scripps professors, prevented him from obtaining a clearance to work on the submarine problem. Working on the weather problem was only possible because of lobbying on Sverdrup's behalf by Revelle. Though scant, they found enough data to tune their method, but a problem remained. Some of the data were visual records from trained officers that consisted of wave height and wave period. Other data were novel pen records of waves, which charted the wave height at a single location over time with a resolution of seconds. From the records, they could measure the height and period of each individual wave. How were they to reconcile these two different types of wave observations? The answer was given by a coxswain. Each Higgins Boat had a coxswain, a captain and navigator, who was trained in estimating wave heights. Munk consulted with the coxswains training for Operation TORCH. From their reports, he was able to match the coxswains' observations with a statistic of the charted wave heights, but it turned out to be a very particular kind of average. He found the coxswains’ visual estimations were similar to the average of the ⅓ highest waves in a wave record, and he called this the “significant wave height”. Now, there was a single number that could be associated with a sea state. Sverdrup and Munk now had the means to use all the available data for their mathematical relationship between the weather charts and the wave heights and periods. It was their version of the engineering solution, an empirical relationship that showed how significant wave height increased with wind speed and length of fetch. Previous to Sverdrup and Munk, wave height had been characterized as only a function of wind speed, as in the Beaufort Force scale. Sverdrup and Munk’s innovation was quantifying relationships that accounted for the size, intensity, and duration of a storm. After the storm moves out of the area or dissipates, the waves can no longer grow. They have reached their maximum height and period. At this point, the waves transition from wind sea to swell. Swell is not influenced by the wind but propagates according to known physical laws of water waves. Their second major innovation, and perhaps less appreciated, was that by applying the dispersion relation, Sverdrup and Munk were some of the first to bridge the gap between the mathematically ideal waves and practical information about real ocean waves. The last bit of the Sverdrup and Munk method was what happens in shallow water, where swell interacts with the contours of the bottom, shoaling and refracting and eventually breaking, in short becoming surf. In developing their method, Sverdrup and Munk cemented the concepts of wind sea, swell, and surf into the canon of wave science. Every part of the method, from the inception of waves to their eventual shoaling and breaking on a beach could be arrived at from weather maps of surface level pressure, the familiar lows and highs, which were widely produced by military meteorologists. Now that Sverdrup and Munk were in possession of a workable method, it was time to put it into practice, but there were still the bureaucratic obstacles. It wasn’t just Sverdrup's ability to make progress on tough problems that Munk sorely needed, he also needed Sverdrup’s clout. Harold Sverdrup was a student of Vilhelm Bjerknes, one of the first people to apply physics to understand large scale fluid flow, in the process establishing dynamical oceanography and modern meteorology. Sverdrup spent eight years as the scientific director on the sailing ship Maud for Roald Amundsen’s expedition to the North Pole, before accepting the directorship of the Scripps Institute of Oceanography. At that time, Sverdrup was world renowned and a leading authority in oceanography. In short, he was someone who commanded respect and someone the top brass would pay attention to. Sverdrup’s influence got them a seat at the Operation Overlord planning table. With their new methods and influence over the schedule, they were instructed to produce a forecast. Their prediction indicated a small window of opportunity, otherwise the waves were too large to operate the Higgins Boats. They decided to run the operation in the narrow window. The predictions were accurate enough, the Higgins Boats made it to the beach, and the mission was a success. However, not everything went according to plan. While waves were small during the landings, they began to rise towards the first afternoon, as predicted. The landing craft, already on the beach and in the surf, suffered heavy losses. From Captain Bates: “By the end 1 of the assault's second day, 9 November 1942, 64% of the 378 landing craft and lighters deployed at Casablanca's Fedala beachhead had broached, stranded or sunk in breakers soon reaching six feet or more in height, a condition persisting for the next two months.” (Atkinson, An Army at Dawn, 2002).” For the Allied Forces, the subsequent loss of craft combined with the disastrous Operation Jubilee, a failed amphibious invasion of a northern French beach just two months prior, renewed interest in the surf prediction problem. The stakes became dire as an even larger landing was in the works, Operation Neptune. The Allied Commanders were betting everything on this operation and everyone, even at the highest levels, was aware that surf could make or break the next stage of the war. As Roosevelt noted in a message to Churchill dated 3 September 1942, "... bad surf on the Atlantic beaches is a calculated risk." It wasn’t just that the Higgins Boats needed to make it safely to the shore, but there was to be a 15-week logistical operation of transporting troops, equipment, and supplies over the beaches. The efficiency of the operation depended on the wave conditions, so an accurate prediction would be of tremendous tactical value. Munk and Sverdrup returned to La Jolla in May 1943. They began to workshop their method with meteorological officers, so-called Weather Warriors, who traveled to California for the training. Officer Charles Bates, already familiar with Suthons’s method for wave prediction, was in attendance. Munk has remarked that he learned so much from the students that at the end of a one-month course, they would have to totally rewrite the curriculum for the next month. And it went on like that, month after month. All in all, they graduated about 100 meteorological officers who were ready to apply the evolved Sverdrup and Munk method. These men and their new skills were shortly to become central in the new offensive effort brewing on the coast of England. By this time in the War, the Allied Forces had reached a crucial moment. A point that would turn the tide way or another. Operation Neptune, under the command of General Eisenhower, was to be a large-scale assault centered around an audacious invasion of coastal France. A tremendous buildup of troops, ships, aircraft, and equipment began in England in the spring of 1944, the largest of the war. The troops would travel by sea and air across the English Channel, ships would blanket the sea and planes would cover the sky. This grand military plan left no stone unturned when it came to understanding the risks involved. Large ships could not deliver troops and supplies to the beach directly. They had to be transported via Higgins Boats. There would be a myriad of landing craft for different purposes, but a typical Higgins Boat would be laden with 30 or more troops. These would be the life-blood of the battle. If the soldiers didn't make it to the battlefield, the battle would be lost before it could be fought. As Churchill stated in his diary, “The destiny of two great empires are seemingly tied up in some God damn things called [Higgins Boats].” Wave prediction was to be central to avoiding catastrophe. Since surf relied on weather, and weather cannot be predicted more than a few days in advance, a rough schedule was dictated by the seasons. The North Atlantic was notoriously rough and stormy in the winter, so they opted for the more placid Summer. The beaches of Normandy would not be complicated by swell from faraway sources, since they generally faced north and were protected by the Cotentin Peninsula to the west. Therefore, wave prediction was simplified to using the local wind speeds, fetches, and durations to give the wave heights and periods. Waves were not the only factor. A full-moon was desirable in order for pilots to hit targets and drop nearly 13,000 paratroopers in the predawn hours. The Germans, anticipating an amphibious invasion, deployed a dense network of obstacles in the intertidal zone that would disrupt the path of landing vehicles. The tidal range in Normandy is about 20 ft, alternately concealing or revealing 200-300 ft of beach. The Army wanted a high tide, which would minimize the length of beach an infantryman would need to clear. The Navy wanted to go at low tide so that the obstacles would be obviated, and hopefully obliterated, by a vanguard of Army Engineers armed with explosives. The compromise was to time the dawn invasion to coincide with an incoming tide. An incoming tide would help propel the Higgins Boats toward shore, where the tide would be low enough for engineers to blow the obstacles and open a navigable path. The length of the beach would decrease as the morning advanced. To recap the requirements: low tide, occurring just before dawn on a full moon, implying a larger than normal spring tide, in the mild summer season. This severely limited the potential dates. Supreme Allied Commander Eisenhower chose June 5th, 1944. In preparation, the Royal Navy initiated a Swell Forecast Section. The name “swell” was intentionally misleading, to hide the fact that they were considering landing on beaches protected from the Atlantic swell. The leader of the section, Lieutenant J.H.C. Fulford, RNVR, established a network of 58 wave observation stations covering a large, synoptic area off the coast of western Europe. Four of these stations were newly available analog wave sensors based on recently developed marine hydrophones, an early kind of pressure sensor, the rest were "Mark-I eyeball observations'', a military euphemism for visual observations supplied by His Majesty's Coast Guard. The coastal observers were instructed to record the height and period of every wave over the course of 3 minutes. The next step was to calculate an average and find the maximum. The average wave height and period and the maximum wave height were communicated back to the Admiralty by code. The Admiralty devised a statistic, halfway between the average and maximum wave height, that they referred to as the “effective wave height”, which, coincidentally, was remarkably close to Sverdrup and Munk's significant wave height. 54 visual stations, making 3 observations daily, resulted in 1,100 wave reports every week, with the hope that the volume of wave measurements would overcome shortcomings due to innate subjectivity. They tested both the British method of Suthons and the Sverdrup-Munk method, and the method of Sverdrup and Munk won out because it was more accurate, and it was “presented in a much more usable fashion”. It was decided that they would use Sverdrup and Munks method fine-tuned with their data and began producing operational forecasts. As June 5th approached, a joint team of officers from the Royal and American meteorological services made wave predictions based on synoptic weather maps. On June 3rd, the maps indicated the development of a gale in the North Atlantic that was propagating west. They awaited confirmation from weather observers. In Blacksod, Ireland, Maureen Flavin Sweeney, the postmistress, awoke at 1 am to make weather observations. It was her 21st birthday, and fullfilling her duty every hour at that point. Weather observation was then under the post office and Blacksod was the most westerly station in the UK, therefore being the first to register incoming weather systems. In the early morning hours, she measured a drop in air pressure, an uptick in the wind, and a slight drizzle; the first whispers of incoming inclement conditions. These observations were soon backed up by additional stations and all but confirmed an approaching gale. The gale was serious, and large waves were predicted in the English Channel. It became obvious that while the tide was optimal, the seas would be too high for the landing craft. However, the following day the seas were predicted to fall to 6 ft, just on the operational limit, and as the gale passed the seas would continue to fall the following days. Eisenhower weighed his options. Everyday, the tidal minima shifted by about 30 minutes. So low tide would occur 30 minutes later on June 6th. This was no longer ideal, but was still workable, while a delay to June 7th would imply a full hour shift in low tide no longer in line with dawn. The next pre-dawn low tide didn’t occur for another 14 days, but this would be a new moon, not great for the pilots, but most of all Eisenhower was terrified of losing the element of surprise. For Eisenhower, the best two options were either to go on as planned or delay 24 hours. He pushed back the invasion by one day. Once Eisenhower made the decision, a juggernaut had been set into motion and there was no turning back. With disaster on his mind, he anxiously drafted a resignation letter to President Truman. About 10 miles offshore of the French coast and well before sunrise, American and British troops began to load into Higgins Boats that hung like life-raft off the side of the large battleships. The Higgins Boats were lowered to deck level and, 30 at a time, soldiers clambered across a gangplank into the small boats. Once laden with crew, the Higgins Boat would be lowered into the ocean under the direction of a coxswain who manned the engine. As predicted, the wave height had dropped but remained balanced on the knife edge. The rough seas were a shock to many. They were unsettled by the wet and cold and struggled against sea-sickness, vomiting into bags and discarding them into the sea. It was a miserable start, but they were alive and this meant they had a chance. This was to be the first of many perils for most troops making amphibious landings, because almost all the 133,000 troops would make it to the beach. June 6th, 1944 became known as D-Day, and it was perhaps the most crucial turning point in the war against the Nazis. It is no exaggeration to say this moment, this single decision to delay the invasion, a decision weighted by waves, changed the world. Prime Minister Winston Churchill in a speech to the House of Commons said, “Operation Neptune was the most complicated and most difficult that has ever taken place. It involves tides, winds, waves, visibility both from the air and the sea standpoint, and the combined employment of land, air and sea forces in the highest degree of intimacy and in contact with conditions which could not and cannot be fully foreseen.” Foresight was exactly what the method of Sverdrup and Munk gifted the Allied Forces. For the rest of his long life, Munk remained humble about his role “We were not doing wave prediction but lucky extrapolation from inadequate data''. However, in 1965 Prof. Blair Kinsman of Johns Hopkins University gave Munk’s work the proper gravitas “There are some thousands of World War II Veterans alive today who would have been dead in the surf had Sverdrup and Munk not done their best with what they had”. Munk took great pride in this quote, and rightfully so. Eisenhower’s appreciation for the performance of the day can be summed up thusly: “Andrew Higgins ... is the man who won the war for us. ... If Higgins had not designed and built those LCVPs, we never could have landed over an open beach. The whole strategy of the war would have been different.” This story is incredible on its own, but what happened shortly after D-Day takes it from the realm of victory through ingenuity and ingeniousness and perhaps some luck to one approaching pure cosmic fate. While the conditions were not ideal, Eisenhower felt a distinct pressure to go on the 6th in order to maintain the element of surprise. Had they not gone on the 6th, the next opportunity was not for another two weeks, owing to the fact that the landings needed to happen on a particular phase of the fortnightly tidal cycle. Eisenhower was convinced that the ever snooping Germans would discover their plans in the intervening two weeks, and so he pushed in the chips on the 6th. While we can not know if they would have been found out if they had delayed, we do know the loss of Higgins Boats could have been catastrophic. A massive storm, entirely missed by the meteorologists, hit exactly 2 weeks after D-Day. Being based on the pressure maps produced by the meteorologists, the surf prediction would have indicated benign conditions. As it was, when the storm hit the newly installed infrastructure for transporting troops and supplies, known as the Mulberry harbors, was totally disrupted and many ships were destroyed and abandoned. Upon hearing about the havoc wreaked by the storm on D-Day +13, Eisenhower said “I thank the gods of war we went when we did.” As it was, Eisenhower’s resignation letter remained unsent. References Used in Text and Notes
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