Why did the American's mulberry harbor not hold up after D-Day?
07.06.2025 13:04
Had our five critics had that aspect of the Mulberry situation consciously in mind, I think that they would have raised the issues that I have raised here, before writing their own answers.
“In a representative example, LST-543 discharged its cargo on D-Day [June 6], came back across the Channel on June 7, loaded up again at Southampton on the eighth, delivered that cargo on the tenth, recrossed the Channel on the thirteenth, and made another delivery on the fifteenth.” The delivery we see here thus must be on the eighteenth – the day before the storm.
That dirt embankment in my own 1963 photo from my own house in Mystic when I was 8 years old? That’s my own Mulberry floating pier, my own bridge on the River Kwai. That’s the precedential personal image I had in mind before I ever heard of Mulberries or the River Kwai.
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So: why did the British take the trouble to complete floating piers at Mulberry B?
Thus have we gone from studying logistics into learning about popular mass psychology. That was unexpected!
I have not discovered what the planned D-Day deadline was for operation of the British floating piers. The British did not have any of their floating piers operational by the time the storm hit on June 19. And by what date did the British have a sufficient number of tugboats and lighters at their own beach to enable them to execute the “by the book” plan for construction?
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The next day, the Americans launched a major offensive that within a week forced-back the Germans a substantial distance. Supplies from the Mulberry B floating piers could not have gotten to the front fast enough to be part of this 0- and in any event would have been British supplies not available for this offensive:
The five critics judge this project like two civilian firms, each hired to construct the same pre-fabricated kind of bridge across a gorge, separated by five miles. Who built the best bridge?
Now, that’s comparative, and does not tell us the amount of material in place; Mulberry B was overall bigger than Mulberry A, and it appears that the British floating piers were to be much longer than the American floating piers. So there might have been a comparable amount of floating-pier-material in-place at the British piers as at the American piers by June 19, yet not comprising the same percentage-of-completion.
The British wanted to abandon Mulberry B in mid-October. But the US, looking at European coastal waters swarming with full cargo ships from America that had no place to unload, saw Mulberry B as a way of unloading some Liberty Ships, primarily of ammunition. At pages 58-60, “Logistical Support of the Armies” tells us:
She has her own website, as part of “LST Scuttlebutt,” titled “Run for your Life! – the Epic of the USS LST 510.” “Run for your Life” is not exactly the concept her current owners want you to be thinking about when you’re aboard her – it refers to her collision in the fog with a Liberty Ship – but your kids will love it.
The major difference is that Cherbourg, the best (though damaged) port in the area, along with most of its peninsula, was not in Allied hands on June 18, but was by July 24; and by July 31 St. Lo and a large area south of it was taken away from the Germans.
That I-95 highway has been in operation for 60 years since then. And no one in 2024 remembers, or can care, whether that stretch opened in one month or another in 1964, or indeed, whether it opened in 1964 or in 1974.
The ferry carries her battle-ribbon from World War II (you can see on the lower-left orange life preserver the name “Cape Henlopen”):
A major reason for building the floating piers was to land vehicles by driving them from the LSTs to the above-high-water line on the beach. That’s what the Americans did on June 16, 17, and 18. The first vehicles using a floating pier at the British beach started on July 24 – five weeks after the Americans had accomplished that feat. Below must be the “LST pier” on the map above:
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But the military context – especially offensive, attack-oriented operations – is completely different.
Over at Utah beach to the west – which was never planned to have a Mulberry – 109,134 long tons of cargo came in, in addition to Omaha’s supply, during all of June. Utah would, by mid-November, deliver 163,529 vehicles, 801,000 soldiers, and 726,014 long tons of cargo – without any floating piers ever planned.
And the larger point to make is that in assessing constructions whose purpose is military logistics, the military purpose of the construction, including the timing, must always be kept in mind – by everyone who is motivated to become a competent analyst of, and advisor for the future, regarding military operations. This is being a professional in educating oneself in military matters.
If the tugs and lighters weren’t at the beach – and they too would all have had to have come over from Britain – the SeaBees can’t be blamed for failing to do what they did not have the tools to do – even if it was in the “book” to do those things.
Prior to this storm, one source tells us, “By June 18, with its third dock still uncompleted, Omaha Beach had landed 197,444 troops, 27,340 vehicles and 68,799 long tons of supplies.” All this material was available to the troops in the field to fight the Germans back deeper into France. But almost all of it came via over-the-beach techniques, not using the floating pier.
“[I]t is appropriate to include a note on the British Mulberry … since that installation operated on U.S. account for about a month. … By mid-October Mulberry B had assumed more importance to the Americans than to the British, for it had been decided to discharge U.S. Liberties [ships] there. The first unloading of U.S. ships had actually begun on the 13th. … [T]he sole value which the Mulberry now had even for the Americans was that it relieved the shipping backlog …. Unloading of Liberties necessitated the use of pierheads and entailed a risk of losing part of the Whale bridging making up the pier at Arromanches in case bad weather suddenly broke up the port. … [On Nov. 2] one pier and pierhead were left for U.S. use. … Mulberry B ceased operating on 19 November, the same day on which discharge at Omaha Beach came to an end. The cargo which U.S. forces received through the British Mulberry was actually negligible in quantity, for the total intake in the five-week period was a bare 20,000 tons, consisting chiefly of ammunition from ships lightened at Omaha.” This last phrase means that ships came into Omaha beach, transferred ammunition to lighters off that beach, which then motored over to Mulberry B (which was not very far away) to put it onto trucks at the pierheads.
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Towing the Mulberry components from Britain to Normandy appears to have been a structural weakness in the overall Mulberry plan. A 2004 US Naval Institute Press article “Bringing Order out of Chaos: Rescuing Force Mulberry” begins “one weak thread threatened to unravel the astonishingly innovative artificial harbors, called Mulberries …. It had to do, of all things, with tugboats.” In mid-April 1944, six weeks before the invasion, American Navy Captain Edmond Moran, who came from a family long in the tugboat industry, was put in charge of collecting heavy-duty tugs and smaller tugs, and training the skippers and crews as best he could in towing the large components that collectively made an entire harbor.
As I write, the next available date you can travel on LST-510 (Cape Henlopen) is June 21, 2024:
The British shut-down operations at Mulberry B in mid-November, thus operating the floating piers for four months. The U.S. Army book “The European Theater of Operations: Logistical Support of the Armies,” volume II, Sept. 1944 to May 1945, has a wealth of information for logistics-nerds, about the vast oversupply of US cargo ships, in the hundreds, in September and after, coming straight from America to continental Europe and then having to wait, like warehouses with engines, for weeks before they could be unloaded. The reason for delay was the lack of deep-water ports with cranes to unload large heavy items such as boxed vehicles, railroad locomotives, and other things packed in the US for safe shipment, but not making a stop in Britain to be offloaded and repacked for easy unloading.
Below is a photo of what must be the western of the two roadways from the “stores piers” in the map above (judging by its angle into the town, and no visible pier to its west, the right in this photo):
This LST beaching system made the Mulberry floating pier concept irrelevant at Normandy – and not just for the Americans, but also for the British (who designed the Mulberry floating pier system) as we will now see.
Why does he think this way? Because he is “civilian conditioned.” Part of it is his civilian-oriented experience in India, but part of it is his being British – where competent performance is the moral ideal.
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We do know that it took a much longer time after D-Day, as compared to the Americans, before the British made their floating piers at Mulberry B operational.
In the military context, first moment of delivery matters.
There is, I think, an aspect of this fictional engineering colonel’s kind of attitude in our five earlier critics. Had they been thinking in military, not civilian, terms about this question, thinking not so much “is this a perfect build” but “what is necessary to throw-back the Germans between June 6 and June 18, 1944,” I think their whole approach to the question would have been different.
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“The Navy acceded to Army requests to let LSTs unload by “drying out,” i.e., beaching on a falling tide and offloading until the rising tide refloated them. This expedient contributed greatly to the ability to offload these valuable ships quickly. … By the end of June, over 432,000 troops, 70,000 vehicles, and 289,000 tons of cargo had arrived over the beaches (respectively these were 71.8, 64.5, and 80.5 percent of the planned movements). … The loss of the artificial port [due to the storm] did force the Americans into greater reliance on deliveries over the beaches, but the transfer rates for Omaha and Utah beaches far exceeded expectations.”
I conclude with another thought on the subject of warfare logistics, which also relates to psychology.
Note that the original plans for the Mulberry harbors was for 5,000 tons per day. The Americans delivered three times that amount via LSTs, without Mulberry floating piers.
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Look again at the June 18 lines when Mulberry A’s two piers were ready to operate (prevented on June 19 by the storm):
Here is the battle-line as of June 18:
The British-constructed floating piers just weren’t ready in time.
It takes a dramatic turn at the end for him suddenly to realize that his proper context for action is military, not civilian, and that he never should have built anything competent here, for an enemy, and now it is his duty to destroy the excellent thing that he made.
The 1947 US Government “Building the Navy’s Bases in World War II,” volume II, says at pages 116-117: “at Omaha the construction work was about 85 percent completed when the storm hit, while at Arromanches [the British Mulberry site] the work had made far less progress.”
But rather than diverge off into such speculations, we first must complete our practical examination of the Mulberry floating piers.
What was needed was called “alongside berths” where a real ocean-going cargo ship (not an LST, even though it too was ocean-going) could tie-up alongside and use either its own deck-mounted cranes, or port-based cranes, to unload.
But instead they have seen it as a comparison of two civilian firms building comparable bridges for use by a civilian society living in a peaceful land.
The US Corps of Engineers book “The War Against Germany,” at chapter XVI, page 344, tells us that after the storm “All LSTs dried out on the Fox beaches at Omaha, where there was less wreckage. By using every available LCT [the much smaller landing craft tank], LCM, and DUKW [the amphibious “duck”] to ferry material from ship to shore, the brigades began to realize a potential for moving supply and troops across an open beach that the planners apparently had not recognized. … Tonnage figures exceeded the planned daily tables consistently between 24 and 30 June.”
The colonel of the bridge-battalion sees that the Japanese are building an incompetent bridge – so he (the fictional character, not the real-life inspiration) jumps in to build a proper one – which is aiding his own military enemy.
I keep thinking of the great book and movie, Bridge On The River Kwai. I know that the book and movie are totally unfair to the real British engineering officer who inspired them, because he did not make the mistake that his fictional version (played by Alec Guinness) does.
By the evening of June 18, the “western” of the three planned American piers also was ready to begin operations on June 19.
And as the Americans named their Saturn V rocket-launch site after the President who inspired the effort – the Kennedy Space Center – so too did the British name Mulberry B after the Prime Minister who inspired the effort – Port Winston.
Only the capture and renovation (after very effective German destruction) of real ports would serve.
But there does become a defect to this viewpoint, when directed not to civilian operations where reliable longevity of the product into the future is what matters, but to offensive, attack-oriented military operations such as the Mulberry piers.
In the military context, what matters is the delivery of the service as early as when needed, for the short period needed.
The battle lines are so advanced by July 24 that in no way can it be said that Mulberry B’s floating piers aided the success of the invasion at its most critical time: the month of June. As these battle-lines show, the British had already captured Caen by July 24 without the aid of a single vehicle delivered over any floating piers. And by July 31, the Americans had swept significantly further south.
But the British did not let “Mulberry slowness” stop them: the British delivered 144,000 vehicles by July 24 without using the Mulberry floating piers. They must have used beached LSTs and used the other techniques that the Americans did.
Obviously, all bridge elements trapped in Britain on June 16 and 17, whether or not they then sank during towing on June 19, could not have been assembled “by the book” at Mulberry B before the storm hit on June 19.
Consider the example of two beach-front lots, on each of which a different contractor is supposed to build a prefabricated house by a date certain. Contractor A, cutting some corners, builds a house on lot A by the deadline, which the user finds suitable. Contractor B, having followed the rules to the letter, has hardly built anything on lot B by the same deadline. A storm comes and covers lot A with the debris of a destroyed house – but lot B has no debris – because there was no house on it in the first place. There’s less destruction on that lot because there was nothing on it to be destroyed.
And if there was no “by the book” assembled British pier in-place by June 19, it is speculation to assert that an American “by the book” installation would have been sufficient to preserve the American piers against this freak storm.
The Americans had not waited for the pier to be finished before bringing-in supplies by large “landing ship, tank” bow-opening ships (“LST”). Initially the US Navy did not want to use the procedure of beaching the LSTs a bit after high tide, and thus leaving them stuck in place for 12 hours until floating off at the next high tide, while there was a chance of German air attack and artillery fire:
Six weeks after the deadline, Contractor B, following all the rules, finishes the house on lot B – and no equivalent storm ever comes along afterwards to test it. And then Contractor B taunts Contractor A “if you’d built your house my way, it would still be standing, but instead your lot got covered with ruins.” It’s like two undergraduate students in college, one of whom takes a graduate-level test and gets a D, and then the other student says “if I’d taken that test, I’d have passed with a C.”
The delay may have been due to sunken deliveries of road material, more than due to a slower “by the book” construction approach.
Some LSTs are still in service 80 years after participating in D-Day – including one that still carries Americans and American vehicles: LST-510, which delivered cargo and men on June 6, 1944. LST-510 continued in Britain-to-Normandy service through January 1945. Put into the “mothball fleet” for 15 years, she was sold for ferry service in 1960, then spending 23 years crossing Chesapeake Bay and then between Delaware and New Jersey, before being sold for ferry service across Long Island Sound in 1983 – but still bearing her Delaware name of MV Cape Henlopen. She has served on that line for the past 41 years, and counting. Her operators are currently commemorating her 80th anniversary D-Day service on their website:
In the civilian context, it doesn’t matter very much precisely when each bridge goes into operation. Once the bridges are open, and traffic is flowing across both, no one remembers that one opened a month later than the other one.
What matters to him more than anything else is: is this bridge being built competently? Are its footings sound, its deck level? It is immoral to build a bad bridge, to build a bad anything. Humans must always do a first-rate job.
It may be that the slowness of completing the British floating piers stemmed from the realization by the British, as well as by the Americans, soon after the storm, that they did not actually need the floating piers – and thus, the British may have dropped them lower in their priorities. That would have been the smart move, frankly.
The same point is valid if we turn from vehicles to soldiers. Here is the chart on personnel as of July 24:
How did the British overcome the towing sinkings that would have prevented completion of their floating piers? As one of the storm-damage photos above shows, the components of the American floating piers were intact, shifted out-of-line but not destroyed. The Americans moved these materials after the storm to the British beach (which was not very far away to the east) to replace the materials sunk while in tow.
The Kwai situation is: a British military bridge-building battalion has been in India for decades before World War II, building bridges for civilian purposes. Then, being shifted to Singapore, they are captured by the Japanese. The Japanese take them to a camp in the jungly north, and assign them to build a bridge – this is the expertise of these British soldiers – which the Japanese will use to aid their military operations against the British in Burma (now Myanmar) and India – against the very people the battalion is part of.
The charge of slip-shod work arises from the fact that three days after the American center floating Mulberry pier went into operation, a freak storm beginning on June 19 through 22 wrecked the floating piers so badly that the Americans decided to abandon the project and rely solely on over-the-beach LST deliveries.
And when you board her, take these photos with you, from her wartime service – including when she collided bow-to-bow with a Liberty Ship in February 1945. That’s the same ship you’re on now:
Essentially, the Mulberry concept was bypassed and made obsolete by the LSTs. The LSTs were a joint British-American design, with 1,050 LSTs built in America; Canada and Britain built 80, and the Americans allocated 113 of their builds to Britain under Lend-Lease.
And even if we knew that information, we still do not have a fair comparison available to us, because all sources say that the storm was materially weaker at the British site than it was at the American site.
Did the SeaBees of the 108th have the tools necessary to execute the British plan “by the book” by June 18? This poses the question of how many small “at the beach” tugboats and lighters would be necessary in order to execute the “by the book” construction plan. The five prior answers complain that the Americans placed only half of the special “kite anchors” designed to keep the floating pier straight – but how many tugs and other lighters were necessary to do that?
Luckily we find a short summary of the D-Day activity of the very LST in the above two photos, LST-543, in Craig Symonds’ book “Neptune” at page 317:
But that was civilian – and the Mulberries and the Kwai bridge were military. And thus they require a different basis for analysis than does US Interstate Highway 95. We must avoid being that Kwai colonel played by Alec Guinness, who erred by harming his own morally-worthy people by applying civilian principles to a military fighting situation.
The US Navy SeaBees of the 108th thus had a deadline to meet: June 18.
Other sources say that half of the pier sections intended for Mulberry B sank in tow in the English Channel. The website of The British Friends of Normandy Trust says “2½ miles of roadway … sank offshore.”
The book “The Big ‘L’: American Logistics in World War II,” in Barry Dysart’s chapter 7, pages 376, 377, and 378 tells us
An Imperial War Museum website says that by June 25, “Mulberry B Begins to operate as a harbor,” but “as a harbor” can cover any type of supply delivery, including over the beaches. The comment cannot mean that the floating pier itself was in operation just three days after the storm, despite the sinking of miles of roadway in the Channel and the fact that no items from the American beach could have gotten there by June 25.
The Eisenhower Presidential Library website tells us that by June 30 over all the beaches, British as well as American, 148,000 vehicles had landed. The Britannica website gives even more by June 30: “nearly 200,000 vehicles.” But not one of these came via a British floating pier. Here, from an official SHAEF report, is a chart of the vehicle-landings from the British floating piers, by dates:
I have long admired the British culture for establishing, as a moral goal for each individual, competence and commitment to do, personally, the best, soundest management and engineering and construction of everything they undertake to do. It is the ideal that every people should have – certainly totally the opposite of those cultures where every bridge is seen as an opportunity for looting-away the money assigned to build the bridge, and thus stripping the people of any bridge at all.
We assess civilian projects on how well they work and how long they work.
Here is the original plan for Omaha Beach at Normandy, with an expected capacity of 5,000 tons of supplies and 1,440 vehicles per day. No similar system was planned for the other American beach, Utah, to the west. The D-Day plan called for all three floating piers to be operational by “D + 12,” meaning June 18.
The D-Day plans also included a “Mulberry B” at one of the British beaches:
Today, June 16, 2024, as I begin writing this (posted June 17) is the 80th anniversary of the first vehicle delivery over any “Mulberry” floating pier in the D-Day invasion of Normandy – by the Americans at Omaha Beach, in “Mulberry A.”
I very much like the fact that it does offend them! There are far too many cultures where the criticism would be entirely the opposite – criticizing the 108th battalion of the US SeaBees for not stealing all the materials and selling them for their personal profit to hide in Swiss bank accounts.
In military affairs, that civilian-oriented thinking is not the way to evaluate logistic performance.
There’s an old saying among those who study military operations, that professionals study logistics. So let’s do a little professionalism today.
The British Friends of Normandy Trust says that Mulberry B “was not completed until July 20” but before that was delivering an average of 6,750 tons per day in July and August. They also note somewhat ruefully in comparison that American deliveries at Omaha and Utah, not using any floating piers, reached “a daily average of 15,000 tons.”
The SeaBees of the 108th met that deadline: the center of the three floating piers was operational on June 16, two days early, while the western pier was complete by sundown June 18.
And this is the viewpoint of our five critics-of-the-US-SeaBees, regarding the Mulberry A floating pier. They see, accurately, corner-cutting, break-the-rules behavior, and it offends them.
All accounts say that there was less destruction on the British beach than on the American beach – but how much pier-length had the British gotten into place by June 19, to be at risk of being destroyed? How much material was there to be destroyed?
Not even the British Mulberry had been planned to be so robust as to serve that function. The Mulberries from the outset had been imagined as an “urgent-invasion” cargo service for smaller vessels coming from Britain. And by September – indeed, by late August, just a month after the British floating piers got into operation – that was no longer adequate to provide what the fully-landed huge continental land armies needed as they swept the German armies out of France, Belgium, and the Netherlands.
The primary purpose may have been for the positive psychological effect on the British people – in much the same way as America in the 1960s used the Apollo moon-landing project: to inspire the people by showing what large, exciting new projects they can design, build, and put into operation. Mulberry B makes an impressive photo from the air.
Nobody criticizes the engineering construction of the LSTs.
Below, we see the “center” of the three planned American Mulberry piers in operation, getting vehicles and supplies to the fighting front on June 16, 17 and 18. Note that the LST requires tugboat guidance for the pinpoint accuracy necessary to connect to the pierhead (the Americans called the pierhead element a “Leibnitz” or “Lobnitz,” but the British called it a “spud”). Managing LSTs into and out of these pierheads, one after the other, would result in lines of LSTs waiting their turn to discharge, and several tugs, and a port-management system for coordinating the LSTs and the tugs with reports from pierhead managers of when to bring-in the next ship:
Meeting the deadline required the SeaBees to skip several important parts of the assembly instructions, as the other five answers say. But this was the trade-off necessary to get the floating piers into operation by the deadline of D+12: swiftly enough to aid the most important part of offensive mechanized army operations – forcing German forces away from the coast – which was the whole point of building the piers.
These post-storm deliveries were accomplished by running LSTs over the tidal flats while the tide was falling, leaving the LSTs to settle gently “dry” and be unloaded, before the rising tide would bring-in the water and refloat them to leave:
Where was the battle line on July 24, the first day of significant vehicle deliveries from the British floating pier at Mulberry B? Here is the map:
I have a personal example: when I was in 2nd and 3rd grade, in Mystic Connecticut, 1963 & 1964, a section of future Interstate 95 was being constructed right along the backyard of our rented house. I used to play on its construction graders and bulldozers after the workmen left for the day. The house is still there, it is just east of the Hoxie Overlook on the south, eastbound side. Here is the photo I took in June 1963, out our back window, of the I-95 highway under construction in my backyard. The gnarled trees are the remains of an exhausted apple orchard. If you are going east and skip the Hoxie overlook, you will drive over this section immediately before crossing the river:
I have not been able to find out just what total length of floating pier that the British had completed before June 19 – using “by the book” British instructions for assembling these British-designed piers – to compare to the two operational American-assembled British-designed piers that were destroyed.
The purpose of the project is to become an improving part of the ongoing civilian society.
“Storm-proofing” the cross-channel towing either was overlooked or impossible. The “cretefleet” blog (referring to concrete, meaning ships that bring construction materials), using the code-name for the truss-bridge-sections (“whales”) tells us that no towing could be done on June 16 and 17 because of rough seas, so on June 18 a large group of tows set forth – and got caught the next day in the same storm that wrecked the American Mulberry harbor:
I thought that an appropriate way I could spend this anniversary day to honor the people who assembled it – a US Navy construction battalion or “SeaBee” unit, the 108th battalion of the 25th Regiment – would be for me to research what they did, and vindicate them if possible from the accusations in all five prior answers to this question that these specific US Navy SeaBees – individuals whose names are knowable – were slip-shod in failing to construct the floating pier in accordance with the British design and instructions.