American logistics in the Northern France campaign

In the first seven weeks after D-Day, the Allied advance was slower than anticipated in the Operation Overlord plan because the well-handled and determined German opposition exploited the defensive value of the Normandy bocage country.

The Northern France campaign officially commenced on 25 July, the day First United States Army began Operation Cobra, which saw the breakout from the Normandy lodgment, and ended on 14 September.

The logistical plan lacked the flexibility needed to cope with the rapidly changing operational situation; the rehabilitation of railways and construction of pipelines could not keep up with the pace of the advance, and resupply by air had limited capacity.

The Advance Section (ADSEC) organized the Red Ball Express to deliver supplies from the Normandy area, but there was a shortage of suitable vehicles owing to political interference and production difficulties.

After the American entry into World War II in December 1941, the European Theater of Operations, United States Army (ETOUSA) was formed, with a Services of Supply (SOS) organization under Major General John C. H. Lee beginning in May 1942.

[1] General Dwight D. Eisenhower became the Supreme Commander, Allied Expeditionary Force, on 16 January 1944, and ETOUSA and SOS were combined into a single headquarters,[2] which was increasingly referred to as the Communications Zone (COMZ),[3] although this did not become official until 7 June.

Studies indicated that Quiberon Bay had an anchorage sufficient for 200 ships, 3,000 yards (2,700 m) of beaches with the required slope for landing craft, and four minor ports close by where deep-water piers could be constructed.

[11][12] In the first seven weeks after D-Day, the skillful and determined German opposition exploited the defensive value of the Normandy bocage country, and the Allied advance was much slower than the Overlord plan had anticipated.

[13] The nature of the fighting created shortages of certain items, particularly artillery and mortar ammunition, and there were unexpectedly high rates of loss of bazookas, Browning automatic rifles (BARs), and M7 grenade launchers.

There were significant differences in the way Patton, a cavalryman, and Bradley and the VIII Corps commander, Major General Troy H. Middleton, who were both infantrymen, conceived operational art,[21][22] the level of war that sits between the means of tactics and the ends of strategy.

[23] When the 4th Armored Division's commander, Major General John S. Wood incorrectly reported that Lorient was too strongly defended to rush, Middleton accepted this assessment.

[20] This did not immediately change the plan;[20] Eisenhower informed the Chief of Staff of the United States Army, General George C. Marshall, that "the rapid occupation of Brittany is placed as a primary task, the difference being that in one case we believe that it would rather easily be done and in the other we would have to fight through the defensive line and commit more forces to the job.

The restricted size of the Normandy lodgment area necessarily resulted in a crowding of the installations, and this problem was compounded by the First Army's reluctance to release the dumps under its control until the end of July.

It took four weeks for the Allied Naval Forces to clear away the underwater obstacles and put the Digue de Querqueville, which had been the largest POL offloading point in the continent before the war, back into operation.

In the attempt to push the pipeline ahead as quickly as possible, the engineers did not always take the time to break through hedgerows or clear minefields, and lines were often laid along road shoulders, where they were subject to damage by motor vehicles.

Up to this point the pipeline had overriding priority, but its construction required the railway system to deliver 500 to 1,500 long tons (510 to 1,520 t) of pipes, tanks, pumps and fittings each day.

These weighed 412 pounds (187 kg) when filled with gasoline, and were disliked by the combat troops, who had little access to handling equipment at their forward dumps, and regarded them as inconvenient and dangerous.

The first rolling stock, two 150-horsepower (110 kW) diesel locomotives and some flatcars, arrived on tank landing craft (LCT) that were unloaded over Utah Beach on 10 July.

Major General Frank S. Ross, the European Theater of Operations (ETO) Chief of Transportation, rode the line from Cherbourg to Carentan in a jeep equipped with flanged wheels.

When Major General Cecil R. Moore, the ETO Chief Engineer, flew over the Saint-Hilaire bridge site at 18:00 on 15 August, he saw a sign on the ground in white cement that read: "Will finish at 20:00."

Congestion resulted when the routes were also used by the First and Third Armies and the Ninth Air Force, with military and civilian vehicles sometimes attempting to move against the flow of Red Ball traffic.

Although fast and flexible, air supply had many disadvantages, the main one being low tonnage capacity, but the variable availability of transport aircraft, their vulnerability to enemy fighters, and their susceptibility to bad weather were also limiting factors.

[77] On 15 August, SHAEF made available an allocation of air transport capable of delivering up to 2,000 long tons (2,000 t) per day to the Le Mans area from airbases in the UK.

12th Army Group allocated 2,100 long tons (2,100 t) per day to such stores during the pursuit, but the Ninth Air Force gave priority to forward fighter airfields.

[78] The air resupply system was also characterized by poor communications, resulting in duplicated requests, and motor transport being sent to the wrong airfields in the UK and France.

Saint-Brieuc was opened in mid-September but discharges averaged only 317 long tons (322 t) per day, mostly coal for local railways and power stations,[93] and it was handed over to the French on 9 November.

It was not badly damaged, and was quickly restored by the 1057th Port Construction and Repair Group,[92] and the first convoy of two Liberty ships and ten LSTs carrying supplies for VIII Corps arrived on 25 August.

[95] Lieutenant Colonel Harold L. Mack, who served on the COMZ staff, described the failure to implement Operation Chastity as the "Critical Error of World War II",[97] but the historian Russell Weigley regarded the commitment to Brittany as wasteful of resources better spent supporting the drive to the east.

[100] Although Bradley's decision entailed grave risk, the US Army's logistical difficulties in the pursuit were not a result of inadequate port resources—in November there were still some 600,000 long tons (610,000 t) of supplies stockpiled in the Normandy lodgment area.

Nonetheless, the logistical plan lacked the flexibility needed to cope with a rapidly changing operational situation,[108] The decision to continue the pursuit beyond the Seine stretched the logistical system to breaking point, and had long-term and far-reaching effects in the form of the attrition of equipment, failure to establish a proper supply depot system, neglect of the development of ports, and inadequate stockpiles in forward areas,[109] all of which were exacerbated by the poor supply discipline of the American soldier.