* Mulberries: The Allied Secret Weapon At Normandy, June 1944

One of the major aims of the great Allied cross-English Channel invasion of German Occupied France on D-Day June 6, 1944 was the securing of the port of Cherbourg on the Cotentin Peninsula in Normandy.

To that end, Allied Supreme Commander Gen. Dwight D. Eisenhower committed three airborne divisions—the British 6th, and the US 82nd and 101st—to drop over Normandy on the night of June 5-6, 1944.

Cherbourg finally fell to the Allies on D+20 on June 27th, but it had been severely demolished by the Germans before its surrender, thus rendering it useless to the invaders as a point of resupply for many weeks.

Ike had foreseen this possibility, however, as he pointed out in his superior postwar memoirs, Crusade in Europe.

“One of the most difficult problems---which invariably accompanies planning for a tactical offensive---involves measures for maintenance, supplies, evacuation, and replacement.

“Prior to the late war, it had always been assumed that any major amphibious attack had to gain permanent port facilities within a matter of several days, or be abandoned. The development of effective landing gear by the Allies---including LSTs, LCTs, ducks, and other craft---did much to lessen immediate dependence upon established port facilities. It is not too much to say that Allied development of great quantities of revolutionary types of equipment was one of the greatest factors in the defeat of the plans of the German General Staff.

“Nevertheless, possession of equipment and gear that permit the landing of material on open beaches does not by any means eliminate the need for ports. This was particularly true in (Operation) Overlord. The history of centuries clearly shows that the English Channel is subject to destructive storms at all times of the year, with winter by far the worst period.

“The only certain method to assure supply and maintenance was by the capture of large port facilities. Since the nature of the defenses to be encountered ruled out the possibility of gaining adequate ports promptly, it was necessary to provide a means for sheltering beach supply from the effect of storms. We knew that even after we captured Cherbourg, its port capacity and the lines of communication leading out of it could not meet all our needs.

“To solve this apparently unsolvable problem, we undertook a project so unique as to be classed by many scoffers as completely fantastic. It was a plan to construct artificial harbors on the coast of Normandy.

“The first time I heard this idea tentatively advanced was by Adm. (Louis) Mountbatten, in the spring of 1942. At a conference attended by a number of service chiefs, he remarked, ‘If ports are not available, we may have to construct them in pieces and tow them in.’ Hoots and jeers greeted his suggestion, but two years later it was to become reality.”

Continuing, Eisenhower stated, “Two general types of protected anchorages were designed. The first---called a ‘gooseberry’---was to consist merely of a line of sunken ships placed stem to stern in such numbers as to provide a sheltered coastline in their lee on which small ships and landing craft could continue to unload in any except the most vicious weather.

“The other type---‘mulberry’---was practically a complete harbor. Two of these were designed and constructed in Great Britain, to be towed piecemeal to the coast of Normandy. The principal construction unit in the mulberry was an enormous concrete ship, called a ‘phoenix,’ boxlike in shape and so heavily constructed that when numbers of them were sunk end to end along a strip of coast, they would probably provide solid protection against almost any wave action.

“Elaborate auxiliary equipment to facilitate unloading and all types of gear required in the operation of s modern port were planned for and provided. The British and American sectors were each to have one of the mulberry ports. Five gooseberries were to be installed.

“Experience in Mediterranean warfare had demonstrated that each of our reinforced divisions in active operation consumed about 600-700 tons of supplies per day. Our maintenance arrangements had to provide for the arrival of these amounts daily. In addition, we had simultaneously to build up on the beaches the reserves in troops, ammunition, and supplies that would enable us, within a reasonable time, to initiate deep offensives with the certainty that these could be sustained through an extended period of decisive action.

“On top of all this, we had to provide for bringing in the heavy engineering and material needed to reestablish and refit captured ports, to repair railways, bridges and roads, and to build airfields. A further feature of the logistic plan---and a most important- --provided for the speedy removal of wounded from the beaches and their prompt transfer to the great array of hospitals in England.”

In his 1959 work---The Far Shore ---Rear Adm. Edward Ellsberg added details: “It was to be the Navy’s job to land (Gen. Bernard) Montgomery and the British before Caen, (Gen. Omar N.) Bradley and the Americans at Omaha and Utah beaches at the base of the Cherbourg Peninsula.

“Montgomery, closest to Paris, was then to delude German Field Marshal Erwin) Rommel into thinking the British were striving desperately to break through and be on their way to not-so-distant Paris.

“But actually, he was not to get away from Caen and his supplies---merely to attract to his British front all the Germans he could, and thus leave Bradley as uninhibited as possible while Bradley and the Americans drove for the first real objective, the port of Cherbourg, at the northern tip of the Cotentin Peninsula. Cherbourg was to be taken by D+17.

“Meanwhile, Operation Mulberry, consisting of two artificial harbors to be brought by the Navy from Selsey Bill (in England) to the Normandy beaches, was to handle ashore all the fighting equipment and supplies needed to hold off Rommel while Bradley was taking Cherbourg.

“It was hoped that, by D+47---a month after its capture---Cherbourg would be reasonably usable as a port. Till then, Mulberry must carry the load---or all was lost.

“Immediately after taking Cherbourg, Bradley on D+22 was to turn southward down the Cotentin Peninsula, punch a hole through the German lines somewhere around Avranches, and then hold off Rommel while (Gen. George S.) Patton, freshly brought from England, and his Third Army were poured southward through the gap into Rommel’s rear…

“On D+42, we were to tow from England around the by then immobilized Brest Peninsula, and start setting up the equipment for a harbor independent of the Mulberries in the (English) Channel---and very different---Between Quiberon Bay on the Atlantic and Operation Mulberry on the Normandy beaches, we could keep the invasion armies supplied through the long months ahead, till Cherbourg, Brest, L’Orient, and St. Mazaire, rehabilitated no matter how badly sabotaged before surrender could finally take over the load permanently…

“Operation Mulberry was at best expected to keep the invasion going…Ultimately, when all the regular French ports were back in service, we’d trade our temporary ports----the Mulberry harbors and Quiberon Bay---for the latest 1944 eight cylinder model of supply, those four captured and restored French ports, and star driving across the Siegfried Line with all our supply problems over…

“With America’s vast resources of production at last flowing freely into France through four real ports, not just through makeshifts, there could be only one answer as to the outcome of Operation Overlord.

“…Operation Mulberry was the first rung of the ladder into France, Quiberon Bay was the second, the four French ports were the third---and then we were over the top, and ready to fight in earnest. I became promptly submerged in hurriedly making a port out of some of the undeveloped real estate fringing the Quiberon Bay waterfront.

Later, “I shoved off…in a staff car, headed south for Selsey Bill and the Mulberries, and now I was looking at them. Gradually, my shock at the unimaginable magnitude of the Mulberry units before me subsided.

“More soberly, I began to fit the pieces I saw before me into the picture they were to make when floated to the far shore---a picture of two vast artificial harbors miraculously to be unfolded under fire before befuddled Nazi eyes on the bare sands of Normandy.

“First and worst of the obstacles came the Channel tides---they were tremendous---from high tide to low, a rapid fall of over 21 feet. The net effect of so terrific a change in sea level was that at low tide on those flat beaches the waterline rushed seaward a quarter of a mile twice each day, moving the shoreline far out from the beach, leaving only wide stretches of bare sands where before a ship might comfortably have floated.

“That Normandy shoreline was like a drop of quicksilver---you couldn’t hold a finger on it in any one spot long enough to let you unload a cargo there.

“Next came the tidal currents. The vast quantities of seawater involved every six hours in the changing ocean levels surged in and out the Channel like swiftly flowing rivers running alternately west and east along the coast as the tides ebbed and flowed---baffling currents of amazing strength, of themselves enough to drive a seaman out of his mind struggling to handle his vessel onto or off the beach.

“Finally the shoreline itself, wherever momentarily it might be, unprotected by any natural promontories or outlying islands, was exposed freely to the full sweep of the seas bearing in from the open Channel. And the Channel was a restless body of water, notorious, historically in fact and fiction for roughness the year round.

“Small craft---let alone larger vessels—in anything but fine weather, would find unloading cargo on those unprotected, surf-beaten sands an unsolvable problem. Those were the major obstacles—in any seaman’s eyes making the beaches untenable fir any long-continued cargo handling, even of light materials, let alone of heavy guns and tanks---unless you held a protected seaport on them.

“Foe each of these insurmountable obstacles to any use of those open beaches, Operation Mulberry was to provide in an unprotected seaport what was needed to surmount them. There, lying off the Selsey sands, shortly to be moved to France, were the answers before me, idiotically purposeless though the whole thing seemed.

“Most important of those answers, of course, was the need for the shelter from the open seas and the never-ending surf. For that, a massive breakwater was required. Massive breakwaters in open coasts take years to build up from the sea floor---everyone knows that, but there, despite what everyone knows, were two massive breakwaters, designed to be installed on the sea floor in France, ready for use in a matter not of many years, but of a few days.

“There before me were the Phoenixs….Phoenixs, code name for the heart of this entire operation---about a hundred of them---those majestic concrete blocks protruding from the surface, staring me in the face like awash warehouse tossed about in insane disarray by some unsubsided flood…

“Phoenixs were the gigantic sections from which shortly to be formed the breakwaters to be. Each Phoenix section was of itself capable of being made as buoyant as a ship.

“It was first to be floated up off the bottom on the English side where temporarily it rested awaiting D-Day, and then to be towed a hundred miles across the Channel to Normandy, there once again and finally to be sunk, but this time ranged end to end with its mates in predetermined line a mile off the beachheads, to make an enclosed and sheltered harbor of the area chosen for invasion.

“Each of these amazing Phoenixs was 200 feet long, 60 feet high, 60 feet wide—a tremendous chunk of hollow reinforced concrete divided into watertight compartments and displacing 6,000 tons—as heavy as the average Liberty ship, as high as a six-storied building, as long as many a city block. Sunk end to end in two long strings off the French coast, these Phoenixs were to form two separate breakwaters, each two miles long, one on the intended American front, one before the British front---20,000 feet altogether of breakwater.

“They were to be sunk a mile offshore in water 30 feet deep at low tide. Then, even at high tide, about 10 feet of their upper structure would protrude sufficiently above the surface to break the waves and shield the artificial harbor inside them from the Channel seas.

“Thus, they would provide inside them the quiet water in which cargo unloading, whether onto pier heads or from small craft beached on the protected sands, could go on day and night undisturbed by surf or waves. “To get sufficient depth for ships inside, even at low tide, the breakwater line had to be planted nearly a mile offshore. There then would be draft enough inside the breakwater line to nearly provide a berthing space along each inner Phoenix wall for seven Liberty ships while they were unloaded, as well as sheltered anchorage for unnumbered smaller craft.

“Next, as the problem to be countered after that of shelter, came those troublesome currents. Something had to be done to break them up. It was provided. A relatively short cross breakwater of more Phoenixs was to be laid at the western end of each harbor, running from the inshore sands outward and perpendicular to the main breakwater, which it was to join at the seaward end.

“That cross breakwater, short though it was, would act like a cork at one end of the harbor, throttling off the dangerous alongshore rivers.

“Finally, but by no means least, there was the pier head problem---a really acute headache. To keep up with the enormous tonnage of supplies necessary with the limited number of vessels available, there must be a fast vessel turnaround on the far shore. That meant that all the unloading of tanks and heavy guns would have to be off the bow ramps of LSTs…but on the Normandy coasts, there were those precipitous tides and their constantly shifting water levels.

“With a water level 21 feet lower at low tide than at high, there arose instantly a complication to our unloading anything onto a pier, except briefly at high tide.”

Continuing, the admiral wrote, “Any normal pier head built at the right level to unload an LST at high tide would at low tide tower so high above that LSTs bows that its ramp could not possibly reach up to the pier head, nor if it could, could any vehicle possibly mount so steep an incline. To this dilemma, there was no answer---except to provide an abnormal pier head.

Operation Mulberry provided exactly that answer---the Lobnitz pier head---an abnormal monstrosity, if ever there was one! The Lobnitz, a tremendous structure, was a vertically moving pier head held at a fixed level above the changing surface of the sea. Regardless of the stage of the tide, it always kept itself at just the right height above the water for unloading LSTs onto it.

“Those Lobnitzs, half a score of them, aimlessly interspersed amongst the sunken Phoenixs, were those factory like contraptions with that forest of protruding tall black towers, always in groups of four, reaching skyward from them like chimneys.

“Those square towers, (four per Lobnitz, one at each corner) just now rising high into the air, were actually four tremendous steel legs to be rammed downward through the Lobnitz hull firmly into the ocean floor at the chosen pier head site, to anchor it there.

“On those stout legs, the movable pier head itself, always controlled by intricate machinery inside its rectangular steel hull, thereafter rose and fell with the changing tides. Always it maintained its deck at constant height above the changing waters, never immersed deeply enough to gain buoyancy sufficient to allow it to float free, always keeping weight enough on its four legs to hold them pressed firmly down into the bottom sand, anchoring the Lobnitz solidly into position.

“And, finally, those scores of massive steel arches, intermingled with all else, looking like sections of highway bridges irrationally afloat on the water, crazily pointed every which way? What might they be? “Those, which I now knew went by the code name of Whales, frankly were sections of highway bridges, each one an 80 foot highway truss floating on all but invisible pontoons, joined together finally on the Normandy beachhead into 3,000 foot lengths, they were to form floating bridges running seaward from just above the high water mark on the beach sands to the point where, well inside the protecting breakwater, but over half a mile out to sea, the Lobnitz pier heads were to be placed.

“Over half a mile out to sea---quite a distance! So far out from the high tide line, that out there, even at the lowest of low waters in that extraordinary fall of the tide, there still remained at each floating pier head water enough to berth end on two floating LSTs. So far out that, for 24 hours round the clock, night or day, regardless of the stage of the tide, regardless of weather, there would come rolling ashore over those floating highway bridges from the Lobnitz pier heads a continuous stream of the tanks, the bulky self propelled guns, the combat loaded trucks bearing the priceless ammunition and supplies—a continuous stream of all the vast tonnage of heavy equipment which only the piers, the cranes and the dock facilities of a major seaport could be expected to cope.

“And for the lack of which facilities in our hands on the French coasts, the German General Staff knew no invasion could possibly be staged successfully.

“There was Mulberry ready to go-over a million tons of it, to form the two artificial seaports destined for the far shore. Thoroughly scrambled in arrangement on the Selsey sands to disguise its purpose, there it rose from the sea---apparently some madman’s nightmare of purposelessness on a titanic scale.

“What did the Nazis, photographing it from high flying planes, think it was?” he asked. “Most likely another British attempt, on a vaster scale than any before, to hoax them? Some new secret weapon, perhaps? Or, God forbid, its actual use? No one or our side knew, but there was endless guessing.

“…Was Mulberry ready to go? Would it ever go? Hastily, I calculated: 100 sunken Phoenixs’ 6,0000 tons displacement each; 600,000 tons of sunken Phoenixs nestling in the mud in the ocean floor off Selsey Bill, all to be torn free of the bottom when the signal to go was given, ready for tow to the far shore, all in the few scant days allowed before and after D-Day.

“Before me lay the equivalent of raising a hundred sunken cargo ships in hardly any time at all---the equivalent in tonnage of raising 10 sunken Normandies” (a prewar French ocean liner)---“with the time allowed for the job not the two long years that wartime task took all the salvage forces that could be mustered in New York harbor to lift one Normandie only, but a few days only for lifting all 10 of them!

“Quite an operation, and to be sandwiched in between two inexorable deadlines---one for starting, one for completion---two deadlines, by the exigencies of war squeezed so closely together that the time between them allowed for the lifting job was sliced to such a thinness as to be practically imperceptible as any filling at all in the sandwich---the biggest lifting job in salvage history, I don’t doubt.”

How successful were the Mulberries in actual practice in Normandy? According to author Douglas Botting in The Second Front, “In the days after the landings, work forged ahead on the assembly of the two artificial harbors, Mulberry A for the Americans at St. Laurent and Mulberry B for the British at Arromanches.

“The whole project was majestic,’ Churchill said, and indeed it was. In a period approximately eight months, some 20,000 British workmen had fashioned two million tons of steel and concrete into 600odd sections that were towed piecemeal across the Channel by more than 100 tugs and assembled into two enormous floating ports.

“At 4:30 PM on D+10, and LST landing craft dropped its ram onto the first completed pier runway of Mulberry A. Two days later, 24,412 tons of supplies and ammunition rolled ashore from the two Mulberries, but then the capricious weather intervened.

“ON the morning of D+13, gale force winds and heavy surf began to pound the Normandy coast, driving landing craft against the piers and tearing sections of the piers from their moorings and crashing them against each other By daybreak on D+16 (June 22nd), Mulberry A was a useless mass of twisted wreckage. Mulberry B, protected by a reef, suffered considerable—but not disastrous---damage.

“Yet so powerful was the momentum of the build up that the great storm caused, in Eisenhower’s words, ‘Little more than a ripple’ in the flow of Allied supplies. When unloading resumed on D+17, the British Mulberry, repaired and reinforced with salvageable parts from Mulberry A, went back into business, and the Americans landed 16,400 tons on the open beaches.

“By Aug. 1, 1944, the armies that had established the Second Front were strong enough to break out of their Normandy beachhead and begin the liberation of the rest of France,” Botting concluded.

Thus, the Mulberries---the Allies’ secret weapon at Normandy---had been a great success.