A Harbor Built From Scratch

BEGINNING IN LATE 1943, THOUSANDS OF MEN IN LOCA tions scattered throughout Britain were busy building huge, strangely shaped objects so shrouded in secrecy that their purpose was a mystery even to the workers assembling them. The most striking of these objects were dozens of vast gray blocks, each 60 by 60 by 200 feet, which looked from the outside like concrete bricks the size of apartment buildings. Inside, however, they had a hollow, cellular structure, which allowed them to float. Some were built in seaside basins and put into open water by removing the basins’ retaining walls; others were assembled on ramps and launched like ships.

All together, 250,000 tons of concrete and the labor of 20,000 men at 28 different sites went into these objects. The workers who were building them speculated, among other guesses, that the behemoths might be floating grain elevators that would be towed across the Channel to feed starving Europe. They were too big to be hidden from enemy reconnaissance, and the Germans thought they were part of a plan to block their harbors.

But the Germans had it backwards. The Allies planned to use the caissons to create harbors, not block them. They were going to be part of a structure code-named Phoenix, which in turn was part of a larger project called Operation Mulberry. The Mulberry concept and the Phoenix units traced their origin to an earlier world war and Winston Churchill. In 1917, as minister of munitions, he had proposed invading Germany’s Frisian Islands with the aid of “a number of flat-bottomed barges or caissons, made…of concrete.” Churchill understood that such objects could not be hidden from the enemy, but he thought it likely that observers would guess that they were “intended for an attempt to block up the river mouths.” In fact he planned to use them to assemble “a torpedo- and weather-proof harbour.”

The idea was never implemented during the First World War, but in the Second, as the Allies gazed across the choppy waters of the English Channel and plotted their return to the Normandy shore, they knew that any beachhead they took would be overwhelmed if thev could not send in reinforcements and matériel faster than the enemy could. For this reason, the Allies thought it essential to control, in the early days of the invasion, a harbor where ships could dock and unload great quantities of supplies—particularly the heavy tanks and big artillery needed to support a large-scale offensive.

The Germans, of course, also understood the importance of harbors. In fact, they had examined the same problem when making their plans to invade Britain and later had built vast fortifications around the crucial harbors of Le Havre and Cherbourg. For the Allies to invade these—the only large ports in range of air support from England—would cost untold lives and require massive bombardments, which would ruin the harbors for weeks while docks were rebuilt and sunken wrecks were cleared.

Amid these concerns, Churchill’s concept for the invasion of the Frisian Islands was resurrected for the Normandy invasion. Rear Adm. John Hughes-Hallett, chief of the naval planning staff, wrote: “Since the French ports were strongly defended, we could not achieve strategical surprise or even tactical surprise. We must to some extent rely instead upon technical surprise.” Rather than attempt to seize a French harbor from the Germans, the Allies would bring their own.

The Mulberry project (a name chosen arbitrarily) was devised by Royal Navy planners in the summer of 1943 and approved at the Quebec Conference between Churchill and President Franklin D. Roosevelt that August. It called for the construction of two separate harbors: Mulberry A, off Omaha Beach near the town of St. Laurent, for the Americans, and Mulberry B, centered on Gold Beach, near the town of Arromanches, for the British. Each of these harbors would be comparable in size to the one at Dover, England, which was also artificial. But Dover was a permanent harbor that had been built over seven years. Plans for the artificial harbors of the Allied invasion mandated construction in two weeks or less.

Sheltered waters for the harbors would be provided by three types of breakwater: Phoenix, Gooseberry, and Bombardons. Farthest offshore would be the Bombardons, floating steel structures 200 feet long and 9 feet deep with fearsome jutting fins projecting laterally. They would be anchored to the sea floor to smooth incoming waves. Next would come the Gooseberry, a breakwater formed of old ships that would take one last voyage across the Channel and be scuttled. At the American Mulberry, Gooseberry ships would be sunk end to end in a line more than a mile long.

THE CRITICAL ELEMENTS OF THE MULBERRY HARBORS, however, were the huge concrete Phoenix units. These were designed to be towed across the Channel at 3 miles per hour; the average unit would travel 125 miles. Off the beaches at Normandy, flood valves would be opened, and the structures would sink—an hourlong process—to form a breakwater nearly a mile off the high-water line on shore. Placement was critical. As one British serviceman recalled decades later, “Too deep and the hollow Phoenix units of the breakwaters would be drowned—the waves would just break straight over them, especially in bad weather, when the wave heights would be greater.” In addition to those parallel to the shore, shorter lines of Phoenixes would run perpendicular to cut down on crosscurrents.

The tides in the area rose and fell 21 vertical feet, but even at high tide the Phoenix units would stand 10 feet abovewater, each one protected by a lone 20-millimeter antiaircraft gun on its top. The tides created a problem for large landing craft. They could beach directly on the sands, but to do that, they would have to be sent ashore at high tide to avoid getting floated or swamped by the rising tide (among other reasons). Then they would lie stranded for half the day while the waters went out and came back in. The solution was another peculiar-looking structure called a Lobnitz pierhead. It had four huge legs, each 60 feet tall, which supported a hull 200 feet long, 60 feet wide, and 10 feet deep, with living quarters between the decks and diesel motors to winch the hull up and down the legs. In this way, the surface of the Lobnitz could rise and fall with the tide, handling cargo operations 24 hours a day. (The name came from the designer and manufacturer, Lobnitz & Company of Renfrew, Scotland.)

Connecting the Lobnitz pierheads to shore were long steel pontoon bridges, which were given the code name Whale. The Whales were built in 80-foot sections that would rest on bargelike steel-and-concrete pontoons. They were designed to extend to the high-water line on shore and would tilt up and down as the Lobnitz platform moved up and down the legs. Plans for the American Mulberry called for six Lobnitz pierheads linked to three Whale causeways, each a half-mile long. Two of these Whales would accommodate cargo up to 25 tons, while the third, meant for tanks, would be rated to 40 tons.

To get all these fantastical structures ready in a matter of months would be an epic task, exacerbated by many factors, including wartime shortages and the project’s extraordinary secrecy. It was impossible to explain to anyone without an extremely high security clearance why anything Mulberryrelated should be a priority. Furthermore, through the end of 1943 project leadership was lacking, in part because many officers took one look at the concept and decided it was doomed.

Nonetheless, planning documents said Mulberry would happen, so work struggled along. Then in January 1944 Capt. A. Dayton Clark was given responsibility for the American Mulberry. Captain Clark was a Naval Academy graduate who had served as commanding officer of the presidential yacht and as an aide to the White House and had moved through a variety of staff positions. Stationed in England, he launched into his new task with a phenomenal, grim intensity. By late February the first Phoenix unit had been completed and began to be used in trials to establish its towability. In March a unit was sunk to prove that the design could remain stable while it settled through the water.

Meanwhile, reality began to force a less optimistic construction schedule. The original plans for the American Mulberry had called for 34 Phoenix units, with 19 more to be built as spares against losses to German attacks. Now the spares were eliminated and the harbor design was slimmed down to 31 Phoenix units. Also, the planned date for D-day was moved from early May to early June, giving Mulberry a little more time to assemble its components.

It was not until May 24 that the first Lobnitz pierhead was connected to Whale bridging off the Isle of Wight and a docking attempt was made with a British LST (landing ship, tank). The host of generals and admirals assembled to witness the moment discovered that an LST docked against the Lobnitz could not open its bow doors. Harried workers cut away sections of the doors with oxyacetylene torches, but then none of the tracked vehicles disembarking from the LST could scramble up the ramp onto the bridging. Several other problems became apparent during the test, and on May 28, barely a week before D-day, orders went out for a set of modifications to all the affected LSTs. Meanwhile, German propaganda radio began to send this message across the Channel: “We know exactly what you intend to do with those concrete units. You intend to sink them off our coast in the assault. Well, we’re going to help you, boys. We’ll save you some trouble. When you come to get under way, we’re going to sink them for you.”

On D-day, June 6, Captain Clark gave his officers an equally encouraging message: “Some of you have made a bad mess out of your responsibilities. There is still a chance that in the days and nights of work ahead you can make a better showing.” The Mulberry convoy set sail at midday, and when it was in the middle of the Channel, in the dark of the ensuing night, Captain Clark’s flagship, the submarine chaser SC 1329 , discovered that it had been issued the wrong code books, rendering radio signals indecipherable. Uncertain whether the assault on the beaches had been successful or not, and worried that the code pouring from the radio was ordering them back to England, the Mulberry con- voy sailed on in the dark.

When it arrived at dawn, the Germans retained enough of the cliffs over the beach to hit the water with small-arms fire, and their larger guns struck out at will. Nonetheless, Captain Clark set his Mulberry force to their tasks. He had the first three Gooseberry ships sunk that same afternoon, and the next day the concrete Phoenix units began to be sited. In the days that followed, Clark sailed up and down the beachfront in SC 1329 like Ahab pursuing Moby Dick. Indifferent to the limits of human endurance, whether in himself or others, he stood in his pilothouse and hurled scorn and bitter invective through a bullhorn—to be heard for miles around—at any man who so much as missed a thrown line. Officers who hesitated, or who presided over Phoenix units that settled out of position, were immediately relieved. He earned terrible resentment from everyone around him, but he managed to force the entire ungainly, implausible project toward completion ahead of schedule.

BY D +4—THE FOURTH DAY AFTER D-DAY—OMAHA BEACH’S Gooseberry was finished. On D + 5 the Gooseberry at Utah was done, 12 Phoenix units were in place, and work on installing the Whale causeways and Lobnitz pierheads had begun. By D+7 all the floating Bombardons were moored. Throughout the installation, German fire and other exigencies forced continual on-the-spot redesigns of the original plans. Whale units were lost, so the bridging to shore had to be shortened. Gooseberry ships at Utah Beach were carried out of position by the currents, so the straight line planned at that harbor became something more resembling two sickle moons side by side.

The night of D + 9 found one of the Whale roadways in place; the Mulberry officers and Navy Seabees who had built it were able to walk dry-shod to the beach. Once there, they could turn and see the breakwater elements spread in a vast assembly on the water, each Gooseberry ship and Phoenix caisson marked by the barrage balloon it flew. D +10, the afternoon of June 16, saw the first functional use of the Lobnitz piers and Whale bridging, when LST 342 docked and unloaded 78 vehicles in 38 minutes. LSTs kept docking and unloading, sending thousands of tons of equipment ashore, and by the next evening everyone involved was exuberant. A second Whale bridge to shore opened on D +11, and the pace of cargo traffic into France accelerated. Plans took shape to reinforce the harbor against Normandy’s winter storms so it could be in use all year long.

On the morning of D +13, a storm began to blow. Giant waves rose and washed over the Phoenix units; their antiaircraft batteries had to be evacuated. Soon the Whale bridges were bucking so badly that all unloading operations had to cease. The wind gusted over 30 knots (35 miles per hour) as the waves grew taller and taller. At last light, a disaster began to unfold: Some of the Phoenix units were collapsing.

That night the storm drove an American salvage barge and five British LCTs (landing craft, tank) into the steel Whale bridges. Desperate men trying to jump from the LCTs onto the bridges were caught between steel and steel. Others, seeing this, jumped into the water and were swept away by the storm.

THE MORNING OF D+ 14 BROUGHT A LULL IN THE WEATHER . A Mulberry officer leaped into an LCVP (landing craft, vehicle, personnel) that happened by and ran it alongside one of the wrecked LCTs. The LCVP was less than half the size of the LCT, but the officer tied the two craft together and dragged the stray off the bridging to where it could be sunk. By this means, one by one, the careening LCTs were dispatched. That afternoon, however, the storm blew up again with even greater force. LCTs that had never been equipped with anchors circled in the harbor with nowhere to go, since the beach was already covered with wrecks and the seas in the Channel were terrible. Soon they began to run out of fuel, and despite warnings, threats, and even gunfire from Mulberry staff, they drifted into the Whales. That evening the raging seas broke loose a number of the floating Bombardons and hurled them into Phoenix units and ships in the harbor.

Fifteen-foot waves tore through the ravaged Phoenix breakwater to hit the Lobnitz piers. Their legs creaked and groaned; it was clear they would soon collapse. Fearfully, the Lobnitz crews opened the clutches on the winches that took the hulls up and down the legs. This let the hulls float directly on the water and saved the legs, but now the hulls were soaring and then smashing downward, and the men could only cling to the platforms, holding on against the water that beat over them. The storm went on for days, and when it was over, a chaotic mass of barges, LCTs, and LCVPs had pounded the Whale bridées until they stood up on their sides.

Not until the night of June 22 did the weather calm down enough to allow an assessment of the damage the next mornine. The Mulberry design had been based on the seas of an average Normandy summer: “Gales of force seven [35 miles per hour] are very rare during the 90-day period considered, and have not been taken into account in the planning of the harbors.” What struck in 1944 was Normandy’s worst summer storm in 40 years, and it ruined most of the Whales and demolished half of the Phoenixes. (The Gooseberries held, saving hundreds of small landing craft that had been tied up against the sunken ships.) Captain Clark, devastated at the ruin of Mulberry A and bitterly disappointed at the decision not to repair it, was evacuated to England and treated for severe exhaustion.

The British Mulberry, only about half completed at the time of the storm, was saved by its location in the protection of Calvados Reef, and it continued to provide good service in the months ahead (parts salvaged from the American Mulberry were used to repair it). At Omaha, cargo operations continued by means of direct landings on the beach, aided by the partial breakwater protection offered by the remnants of Mulberry.

The wisdom of the Mulberry operation has been debated ever since. The Americans prosecuted their European war effort successfully without the artificial harbor, so was it necessary in the first place? Maybe not, but the British Mulberry certainly aided the offensive, and the war might have ended even faster if the Americans had had their harbor (although more tonnage per day was unloaded at Omaha than at British Mulberry). Planners gambled on the weather and lost, but that doesn’t mean it was a foolish gamble. On the other hand, considering the time, materials, and personnel that went into the Mulberries, they may have diverted resources from other areas that needed them more. But successful or not, Operation Mulberry was crucial in giving Allied commanders the confidence they needed to go ahead with the D-day beach landings.

By any measure, the technical achievement of planning, preparing, and assembling the Mulberries is stunning. Just 10 days after D-day, in a place where there had been only sand and a very high tide, there was an entire, operating wartime harbor. To this day the concrete caissons can still be seen laid out in rigorous geometry toward the British beach at Arromanches. At Omaha Beach, during low tide, only the jagged remnants of a few broken caissons are visible, but even these are enough to impress any visitor with the scope of this unprecedented project.