The idea for the ‘Mulberry’ harbours actually originated even before the ill-fated Dieppe Raid, before it was apparent how badly they were needed. In his book ‘Crusade in Europe’ Eisenhower later said, “The first time I heard this idea (constructing artificial harbours) tentatively advanced was by Admiral Mountbatten in the spring of 1942. At a conference attended by a number of the 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 a reality.”
The next mention of such a thing wasn’t made until a year later, in the summer of 1943, when the leaders were again collected together to discuss the proposed landings at Normandy – which offered the element of surprise and better beaches than Calais – and the possibility of taking the port of Cherbourg. According to ‘Neptune’ by Craig L. Symonds, British Commodore John Hughes-Hallett said, apparently as a joke, “If we can’t capture a port we must take one with us.” Again, the idea generated hearty laughter, until someone piped up to say, “Well, why not?” At this later date, when the first attempt at an amphibious landing on 19 August 1942 had failed so badly, the idea didn’t seem quite as absurd as it had previously. Just three months later, in October 1943, the plan had been approved, and construction of the elements that would be needed to turn Mountbatten’s outlandish idea into a reality began.
The hope was that such ingenious harbours would delay by a week or two at least the urgent need to capture a real port. It was important, though, that they be fit for the purpose of unloading up to 12,000 tons of cargo daily, and sturdy enough to endure storms of up to Gale Force 6, lasting up to 90 days. On top of that, since it would be impossible to tow them intact across the Channel, the harbours needed to be built of components that could be transported easily, then assembled quickly once the raiding party neared the shores of France. The design must therefore be both strong and simple.
In the end, as Dr Stephen Badsey’s ‘D-Day’ explains, it was composed of four separate elements. Furthest from the shore was the Bombardon Breakwater, invented by Robert Lochner (oddly enough, he came up with the idea in his bath with the help of a flannel while suffering from flu). These were large, steel structures anchored so as to slow down the waves before they reached the next layer of the harbour, the Phoenix Breakwater. This second, sturdier, barrier was made up of concrete-clad steel frames, designed so that they would be watertight enough to be towed across the Channel, but once there could be flooded and sunk in position. These first two layers would be laid around 2 miles out to sea. The penultimate layer was essentially composed of a load of sunken ships. Old, rickety boats that were no longer suitable for use by the navy either made their own way to Normandy or were towed there. Once arrived, they were scuttled and sunk. Their presence calmed the water above them, thereby creating sheltered areas of sea known as ‘Gooseberries’. Last but not least came a ‘Whale’, a floating metallic roadway that stretched towards the shore and ended in a ‘Spud Pier’, a land wharf where the incoming Allied ships would finally be unloaded. Two of these innovative harbours would be constructed, one to be pieced together off Omaha beach by the Americans, the other off Arromanches, close to the British and Canadian landing beaches.
All the elements were finished by May 1944, and now the troops just had to practice piecing them together in time for the landings. On June 6th D-Day kicked off, and immediately the men began assembling those vital harbours. Starting from the outside, and working in, they worked like lightning, and within 10 days each basic layer had been put into place. The British harbour stood the test of time. When, on 18th June, the feared Gale Force 6 winds actually started blowing the harbour stayed put, though the British loading operations were severely compromised for the 5 days it lasted. The Americans were not so lucky; their harbour rapidly disintegrated. Some blame faulty assembly, others claim that the US beaches were simply more exposed; whatever the truth, the breakwater was breached and rendered essentially useless. It was never to be reconstructed.
While the storm lasted less than 1/3 of the projected supply of men and goods got through. Over 800 ships were damaged and sent to the bottom by the force of the waves, and the commanders began to worry that the men would not capture a permanent port in time. However, their fears proved groundless. As soon as the storm ceased the remaining harbour was patched up with the bits left over from the ruined one, and before long was functioning at full capacity once more. The Germans, broken, exhausted and demoralised, couldn’t organise themselves in time to take advantage of the temporary respite from attacks by the R.A.F., and the critical moment passed without incident. Before long, the U.S. troops would secure the success of the mission by successfully capturing the port of Cherbourg. Before this happened, though, 1.5 million men, 300,000 vehicles and 1.8 million tons of supplies would be landed with the help of the cunningly conceived 'Mulberry' harbours.