To support combat operations. Overlord planners had arranged the prestowage of eight days of supplies in various landing craft, small freighters, and modified Liberty ships. Following a 13-day transition period, the majority of resupply would begin to arrive in Normandy via the larger Liberty ships. By D + 41, planners intended the majority of the logistical requirements to be met by using deep-draft cargo ships berthing at ports the combat forces would by then have captured, supplemented by smaller vessels delivering materiel from England.
To accommodate those ships, planners intended using Cherbourg, Lorient and Brest, minor ports in Brittany and at the mouth of the Seine, and artificial Mulberry i2shots to be laid off American and British invasion beaches. The Mulberries were initially the most important, because the Germans were expected to fight hard for the ports and demolish them if forced to withdraw. Mulberry A, for example, planned for Omaha beach, was to be emplaced by D+4 and to handle seven Liberty ships, five large coastal freighters, and seven medium coastal freighters at one time. The open beaches, counting the tonnage of beached landing craft and lightered cargo in addition to the Mulberry ports, were expected to handle almost 15,000 long tons (1 long ton = 2,2401b, 1,016kg) of cargo each per day by D+10, rising to almost
46,000 long tons per day by D+90.
Such large trans-shipments of war materiel demanded carefiil beach organization, a task assigned to several special engineer brigades. Planners had learned through the painful experience of previous amphibious operations that specially trained troops had to be on hand to clear minefields and obstacles from the beaches and beach exits, manage the landing operations of succeeding waves of troops and the delivery of supplies, and to create and operate depots within the beachhead. Traffic control, both afloat and ashore, loomed as an important challenge, as did the requirement to maintain local security after the assault troops moved inland. To accomplish all these tasks, the engineer special brigades were organized not only with engineering units to emplace, maintain, and operate the artificial harbors and pierheads, but also with transportation, port and amphibian truck companies, quartermaster service and railhead companies, and ordnance, chemical, medical, military police and signal units.
While the beaches would be the principal and initially most important focus of the lines of communications, major combat operations could be contemplated only if the Allies had the use of regular ports. The planners expected to bring a few of the smaller ports into operation quickly, Cherbourg and other of the smaller ports by D+30, and the major ports of Lorient and Brest a month after that. Looking at the situation realistically, no one expected that ports would be ready to use immediately; some reconstruction to repair war damage or intentional demolition would be necessary. For that purpose, engineer and transportation troops were detailed to bring the ports into usable condition by D+90, when deep water facilities were to take the burden of all supply operations.
The scale of the logistical requirements was imposing. In the simplest terms, an infantry division in combat required roughly 700 tons of supplies per day. Projections for early September called for 37 divisions to be ashore, consuming 26,000 tons of supplies each day. That cumulative total of 780,000 tons per month defined a hand-to-mouth existence for the armies. Before they could seriously consider extended offensive combat, reserves, particularly of ammunition and fuel had to be built up, and provision had to be made to replace combat losses in tanks and other major pieces of equipment. Logistics, as Gen. Bradley said, was “the dullest subject in the world” but obviously the “lifeblood of the Allied armies in France.”
Acknowledging the many practical difficulties, Prime Minister Churchill told Eisenhower that “if by the coming winter you have established yourself with your 36 Allied divisions firmly on the Continent, and have the Cherbourg and Brittany Peninsulas in your grasp, I will proclaim this operation to the world as one of the most successfial of the war.” Eisenhower, more confident, predicted that the Allies would stand on the borders of Germany by the coming winter. Everything depended, however, on the speed and success of the buildup in Normandy. In June and July, the race was on to see whether the defenders or the attackers could reinforce the battle front faster.
As events unfolded, developments on the battlefield quickly reduced the carefiilly phased logistical plans to chaos. Neither the British or the Americans captured ports on schedule, and German demolition work, especially in Cherbourg, was much more complete than anyone thought probable. That port did not become operational until July 16, and then handled only 2,000 tons of supplies per day. It remained the most important port until well into August, by which time it could handle around
12,000 tons a day. Other ports, such as Le Havre and Rouen, unloaded substantially less. The ports of Lorient and Brest never became available, and the tenacity with which the German garrisons defended them right to the end of the war gave Gen. Bradley occasion to wonder how much more stubbornly the German soldier would fight when defending his own land. Thus the logistical plan, dependent on good ports, began to unravel and improvisation became increasingly important.
It was therefore fortunate that the special engineer brigades worked with great efficiency and developed the landing beaches into something resembling major ports. Again, the examples of the American beaches are typical. By the end of the second week after the assault (Sunday, June 18), the engineers had cleared the beaches of almost all wrecked landing craft and were well on their way to clearing the minefields behind the sea walls. They pushed additional roads inland to support the increasing number of trucks that were being landed. Trucks, both regular and amphibious, were the key factor that allowed the beach depots of supplies to be built up and moved forward. Toward the end of June, the beaches were handling nearly 100 percent of their planned tonnages each day, in addition to the continued landings of combat troops and evacuation of casualties.
The complicating factor was a storm that arose in the English Channel on June 19 and lasted through June 22. Although not a particularly powerful gale by Channel standards, it was enough to wreck Mulberry A and beach as many as 800 ships, wrecking around 300. The immediate result was that, while roughly 80 percent of the soldiers landed according to schedule, the cumulative volume of supply at D+15 only reached 61 percent of that which was planned. To compensate, the Allies resorted to an extremely inefficient way of delivering critical supplies, but the only one available under the circumstances. For three days, the air forces used their C-47 transports to deliver 500 tons of artillery ammunition each day to Bradleys troops, and particularly to his VII Corps, then poised for the final assault on Cherbourg. Elsewhere on the American front, Bradley drastically reduced ammunition expenditure, a step that virtually halted forward momentum in V Corps. The problem was so severe that a number of coastal freighters loaded with ammunition were beached and had holes cut in their sides to allow unloading. In the long run, the loss of Mulberry A and disappointments with activating captured French ports affected Allied operations all the way to the Siegfried Line. In the short term, tactical problems that kept the forces close to the beaches tended to ameliorate shortcomings of the logistics system.
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