Amateurs Talk Tactics. Pros Talk Logistics. Supplying the Normandy Invasion

It was Napoleon who famously said that an army marches on its stomach. And it’s true. While nobody pens epics about the Quartermaster Corps, without the tools necessary to do the job, victory is nigh impossible. Confederate General Nathan Bedford Forest perhaps said it best… Victory goes to him who “Get(s) there firstest with the mostest.”

One of the reasons Normandy was not more stoutly defended, and that even after the landings had begun the invasion was thought to be a diversion, is that there are no adequate port facilities nearby to support a massive invasion. A reinforced infantry division in WW2 consumed between 600 and 700 TONS of supplies daily. The first day of the Normandy Invasion called for five reinforced infantry divisions on the beaches. That’s a minimum of 3,000 tons of supplies needed on D+1 and every day thereafter. Plus, the needs of the three Airborne divisions once they hooked up with the beachhead units. That’s now about 4,800 – 5,000 tons daily…just for the original units. A total of 46 divisions were earmarked for Operation Overlord. And that’s just basic stuff…food, ammunition, equipment and fuel. Add to that the required stream of replacements and follow-on forces coming in and wounded going out, and the numbers quickly get mind boggling.

That’s the main reason the Germans were focused on Calais. Not only was it close to England, but it had a nice, deep-water port. That's why all the Allied deception tactics rang so true. There was just no way to get around the need for a functional deep-water port. So the invasion couldn’t be at Normandy—and they were right. Without the means to move a massive amount of men and material across the beaches day in and day out, an invasion there would surely fail.

The nearest port to the invasion beaches was Cherbourg on the Cotentin Peninsula. To secure the routes to Cherbourg, Eisenhower committed three Airborne divisions—the British 6th and the U.S. 82nd and 101st—to drop over Normandy in the predawn hours of June 6. Cherbourg finally fell to the Allies on D+20, but it had been severely damaged by the Germans before its surrender. It was more or less useless to the Allies as a point of resupply for many weeks. Fortunately, Eisenhower had foreseen this possibility.

First, the development of practical and effective landing craft by the Allies (including LSTs, LCTs, DUKWs) did much to lessen immediate dependence upon established port facilities. But this revolutionary gear that allowed some resupply over the open beaches did not eliminate the greater need. And remarkable as they were, these craft required relatively calm waters in which to operate. The English Channel can be inhospitable. The Spanish Armada discovered as much. With no natural features to protect them, the Normandy beaches are subjected to the full force of Channel weather. If relying on these amphibious craft alone, a few days of bad weather could cut the Army off from its source of supply. It was a conundrum.

The Allied response was an undertaking so vast and so unique as to be classed by many as completely fantastic: the construction of artificial harbors on the coast of Normandy.

The first time Eisenhower heard of this idea was when British Admiral Lord Louis Mountbatten proposed it in the spring of 1942. At a conference attended by several service chiefs, he stated that if ports were not available, the Allies would simply have to construct them in pieces and tow them in. This was met by both hoots and jeers of derision. But two years later, that is exactly what happened.

Two types of protected anchorages were designed. The first, code-named a “gooseberry,” was to consist of a line of sunken ships placed stem to stern in such numbers as to provide a sheltered coastline in their lee upon which small ships and landing craft could continue to unload in any except the most violent weather. Five gooseberries were to be installed off the Normandy coast.

The other type, a “mulberry,” was in reality a complete harbor…a pier and a roadway/causeway connecting the pier to the beach. Two of these were designed and built in Great Britain to be towed in pieces to the coast of Normandy. The major construction unit in the mulberry was an enormous concrete barge, termed a “phoenix.” Each phoenix was as heavy as a Liberty ship—displacing 6,000 tons—stood 60 feet high, ran 200 feet in length, and was 60 feet wide (tall as a six-storied building and a city block long). Inside, each phoenix was segmented into hollow, watertight compartments. Honeycombed with these, it was a buoyant, seagoing vessel when pumped free of water. But they were so heavily built that when numbers of them were flooded and sunk end to end along a strip of coastline, they would most likely give solid protection against almost any rough seas.

The British and Americans were each to have one of the mulberry ports in their zone of operations. Each consisted of 50 phoenixes. Together they would create 20,000 feet of piers and breakwaters. Working together, the gooseberries and mulberries would supply the Allied army until the port facilities in Cherbourg were operational. As the Allied control of France expanded, additional ports would become available – Brest, L’Orient, and St. Nazaire. It was hoped that after two months or so, these four French ports would be able to carry the load from then on. Until then, however, the mulberries would have to carry the load alone. If they couldn’t, the invasion would simply fail.

On D+10, the first LST dropped its ramp onto the completed pier runway of Mulberry A in the American sector. In two days, 24,412 tons of supplies and ammunition rolled ashore from the two mulberries. Then came near disaster.

On D+13, gale-force winds and heavy surf pounded the Normandy coast, pushing landing craft against piers and tearing sections of them from their moorings, crashing them against each other. It was the worst summer storm in the Channel in almost 50 years. By D+16, Mulberry A was a mass of twisted wreckage. Mulberry B in the British zone was also damaged, though not fatally. Still, Allied supplies continued coming ashore. In fact, the Americans landed 16,400 tons on the open beaches.

By D+17, the British Mulberry, using salvageable parts from Mulberry A, was back in operation.

Throughout the Battle of Normandy and for months after, 2.5 million men, 500,000 vehicles, and 4 million tons of material transited through Mulberries A and B.