Mulberry Harbors and D-Day – A Summary

Posted 6Sep18.

“What is something most Americans don’t know about the D-Day landings?”

The importance of logistics was almost the victim of fragile egos.

I crossed the Channel for the invasion of Normandy aboard a 6,000 ton block of concrete at the end of a long towline, moving at all of three knots astern a laboring tug. The crossing took over thirty hours – no very swift passage. We – that is, the squadron of some ten similar chunks of concrete – had the protection of no convoy of our own; we were much too slow for any convoy to stay with us. But by keeping in the main stream of invasion traffic bound for France, we had the benefit of the occasional presence in our vicinity of destroyers passing us accompanying faster groups, mainly troop carriers.

Edward Ellsberg, The Far Shore, 241.

As part of the follow-on effort to establish temporary harbors on the Normandy coast, the Mulberry harbors posed a solution to the logistical imperative to circumvent the immediate need to capture any of the ports in France and Belgium. These importance of these facilities to the Allied landings was obvious to the Germans as well as the Allies – therefore the effort capture/defend them would consume time and men in the process.

The concept of creating portable points of disembarkation on the European continent was as creative as it was insane. With the northern coast of France problematic with either rocky cliffs or beaches too broad and shallow for the contemporary landing ships to repeatedly beach and offload their supplies, the idea of building harbors made sense. By extending pontoon and ribbon bridges seaward, the inflow of supplies and reinforcements would continue, despite the variances in tide. Artificial breakwaters in the form of intentionally scuttled blockships – “Gooseberries” – and massive concrete cassions – “Phoenixes.” These arrangements would then form two Mulberry harbors, capable of an approximate intended discharge of around 12,000 tons, combined, per day.

The problem of egos rested with the Naval officers in charge of planning. American Navy Rear Admiral Alan Kirk along with his counterpart, Captain Dayton Clark, not only were assigned a posting which was avoided by many U.S. naval officers, but they were routinely stalled by their own ideas for success and the input of the British leadership in charge of the overall project. Conflicting ideas, a confusing quagmire of which official channels to use, personnel/materiel shortages, weather, and geography all compounded into a mess that, in retrospect, is amazing that it ever finally worked when needed.

The reality of the situation was that, following the daunting task of getting all the components in place shortly after the initial invasion and ahead of schedule, and in spite of the storm of 19-22 June 1944 which severely damaged one of the two artificial harbors, cargo operations resumed following the light repairs necessary to the remaining harbor – Mulberry B.

The contributions of these harbors have largely been forgotten in any and all discussions about warfare. The hulking blocks of concrete which were once the Phoenix breakwaters still litter the Normandy coast, as memorials to a logistics effort which are readily overlooked for the more glamorous tales of bravery and violence. However, their importance is not completely forgotten:

Over beach operations were apparently so effective and leadership so enamored by the positive numbers, that by the end of June tactical decisions were being made without regard to logistical realities. The capture of the Brittany ports was delayed as efforts eastward took precedent.

Brett Peters, Mulberry-American: The Artificial Harbor at Omaha, 56.

These ports exceeded their forecasted maximum planned capacity in supplies by the 9th day following the invasion and consistently maintained averages well above the estimates given prior to D Day.

While these events happened after the actual invasion, the Mulberry ports were critical before and after the main effort in keeping the Allied momentum going as the war continued on the Western front.