|The area selected for the artificial port was the small
town of Locmariaquer. Here, the Auray River was deep enough
at 80 feet to accommodate ocean going ships. Inland, a
railroad would be built approximately 10 miles to the town of Auray to
connect with the existing French rail network. A marshalling yard
would be built at the edge of town.
As fascinating as the concept is, and as detailed as the map from the official Army history is, I was unable to find details of the operation in SHAEF records in the National Archives - merely mention of the plan and its status over time. Where the detailed plans are, if they exist, I do not know.
|Had the plan been implemented, this strait would have seen countless Allied supply ships coming and going.|
|To ensure the safety of Allied ships, the Quiberon Peninsula had to be liberated. The peninsula was bypassed as the division commander had been halted and not been informed of the importance of the area. Even today, the long, sandy peninsula is home to many remains of the Atlantic Wall.|
In late August the high command became less enthused with using Brest and Quiberon Bay, and they switched their attention to smaller Breton ports. The tonnage that a port could handle was not the only consideration, the type of cargo it could handle was also a factor. Small ports could unload only small coastal vessels, and these vessels could not handle all types of material and were vital to the British economy. In the first quarter of September, logistics planners leaned toward ending attacks on Brest and advised its containment since capture of both Le Havre and Antwerp was in sight. The battle for Brest continued until it fell to the Allies on September 19th. Brest was never used as a port by the Allied forces. On September 9th, with the frontlines 4-500 miles from Brittany, Eisenhower decided that ports at Quiberon, Lorient, St Nazaire, and Nantes were unnecessary, and the German garrisons could be contained. Also early in September, logistics planners suggested US port development resources be used on British sector ports north of the Seine. On September 27th, it was decided not to develop ports at St.Malo and Cancale. Brittany, once at the heart of Allied planning, was now a backwater, irrelevant to the outcome of the war.The question of Operation Chastity and its potential usefulness remains, but it is a difficult question to answer definitively. One thing is clear, however, Allied logistics planning was fatally flawed, and many people died as a result.
|In 1943, the Transportation Corps estimated that a total of 240 US truck companies would be needed to supply the Allied Expeditionary Force during next years' invasion. Supreme Headquarters wanted that number cut to 100, but a compromise figure of 160 companies was approved. Originally, 2/3 of these companies would be heavy companies with semi tractor-trailers suitable for long-haul use, but in the end this percentage was reduced to around 1/3 of the total- only 59 heavy companies. So from the beginning the high command failed to appreciate the importance of supply. At the end of July, as the Cobra breakthrough was occurring, only 94 of the planned 130 truck companies were available - a figure adequate for the pre-breakthrough situation - but not post-breakthrough exploitation. Why was a breakthrough planned but not its proper logistical support?||
Depot System D+90 - Arrows indicate distance from division to depot
|An alternative contingency to Operation Chastity and the Breton ports was
Operation Lucky Strike. Lucky Strike assumed an opportunity to
quickly and easily capture the Seine ports, which would be used instead
of Brittany. Progress in this 'best case' conjectural operation
is slow compared to what actually happened. Suggested by the
British, the American role is to protect the British flank, and capture
and development of the Breton ports is slow with Lucky Strike. This had important
long term implications for the US Army's ability to advance east which
were duly noted.
This map of the Lucky Strike plan in the National Archives is interesting in that it shows not only depots that the truck companies were to work from - but also the use of railroads to these depots from Cherbourg. Prompt railroad repair depended on an adequate number of railroad repair units in the Overlord plan, and that depended on the expected rate of advance - shown on maps by... phase lines.
|As German resistance collapsed, the Allies were tempted into
moving east all the way into Germany and on to Berlin - regardless of their ability
to do so. Without the requisite truck companies, trucks organic
to divisions - trucks intended to make infantry more mobile
- were removed from their divisions and used in place of the
missing transportation companies. So an army designed with
an emphasis on mobility over striking power was now reduced to walking!
Nevertheless, on September 12th, D+98, Allied armies were at the D+350 phase line. From August 25th to September 12th, the Allies had advanced from D+90 to D+350 in just 19 days. Serious problems arose, and there was no easy solution.
In early September, one plan from 21st Army Group - not implemented - would have idled 19 divisions while 5 Allied corps advanced on Berlin. This plan needed 489 Allied truck companies, but only 347 were available, so trucks organic to the 19 idled divisions would make up the shortfall as well as air transport. The plan necessitated the capture and use of Antwerp by September 15th, so the plan was unworkable and attempted. It speaks to the desperation of the times that the high command had considered this plan - making half of the Allied Expeditionary Force immobile so that the other half could win the war!
The best known supply expedient was the Red Ball Express.
|So what was the root cause of these supply problems?
Phase lines had a profound impact on supply. In an April 7,
at St Paul's School in London, Montgomery unveiled his planning maps
complete with phase lines.
Omar Bradley had prevously asked Monty to eliminate the phase
lines, and he again objected, stating that they limited iniative and
citing the potential to harm troop morale if the men discovered that
they were behind schedule, but Monty assured everyone that the phase
simply for planning - created because it was American standard
procedure, so the phase lines remained. The plan
foresaw fighting German reserves, but it did not envision a decisive
battle west of the Seine. They assumed that the Germans would
fall back and defend river crossings. As the projected advance
progressed, the battle lines became longer - but a potential thinning
of the German line
and a resulting Allied breakthrough was not foreseen. It was
not part of
the plan, and it was not planned for. The plan was to halt at D+90 for a month at the Seine in order to
consolidate and prepare for an advance on to Germany. On
D+120, the US advance would continue after an advance base had been
established in the
Rennes-Laval area with a subsidiary base near Chartres-LeMans.
Plans and projections continued up until D+350, but they became
much more vague with time. Planning had been made for a lodgement but not for an advance afterward.
Although Montgomery claimed that the phase lines would not limit the advance, they were used to plan supply - and so in effect they DID limit the advance. The phase lines were the basis for the number of transportation companies, the number of port clearance units, the number of railroad repair units, and the number of road repair units. If the advance went as planned, there would be trucks, port clearance units, road repairmen, and railroad repairmen when they were needed. But if the advance was slower than planned, men were idle. And if the advance was quicker than planned, there would not be enough trucks, not enough road repairmen, not enough railroad repair men, and not enough men to open up the ports. It was precisely the projected slow rate of advance that assumed a relatively late liberation of the Seine ports which made the Breton ports important.
Only four years before, the Germans had broken through at Sedan and improvised a quick and impressive advance to the Channel coast then across France. Why did the Allied plan not foresee that an Allied army could do the same? Allied thinking was still rigid and methodical in this regard, little different than the mentality of a First World War general. Although both British and American armies aspired to be flexible and adaptable, and both armies often followed, especially at higher levels, a kind of directive command where the general manages and controls. In directive command, subordinates are not trusted to make the right decisions. Both armies had made attempts to copy the German system, where subordinates are told what to do but given the freedom to decide how. The subordinate helped advise the commander, and his views were respected. The Allied high command showed a top-down mentality. It was warned that logistical plans were faulty, but they did not listen. The consequences were severe, and many men died because of an outdated command philosophy and the poor decisions that came from it.
Seduction in Combat: Losing Sight of Logistics After D-Day
Logistical Support of the Armies Vol 1Logistical Support of the Armies Vol 2