Aber wrote: ↑11 Oct 2020, 09:36
TheMarcksPlan wrote: ↑10 Oct 2020, 22:12
which would remove any practical shipping constraints on Bolero buildup.
But not UK port capacity constraints, or building infrastructure in the UK.
So many constraints, so little time.
For one thing, the U-Boat threat was not considered solved until mid 1943, which led to the extraordinary measures taken to protect troop convoys, which in turn took escort assets away from other convoys, which led to those taken losses, and so on. While hindsight tells us the threat was somewhat overstated and the measures in place were possibly sufficient that remains an intangible.
The next problem was the ports as you note. Virtually all BOLERO shipping came in through the western ports, Glasgow, Liverpool, and Bristol. However, the invasion ports were essentially all on the east (follow-up merchant shipping was dispatched from the western ports). That severely overtaxed the port and rail capacity at those ports. The port capacity limit was such that it was calculated the US military could unload a normal maximum of 150 ships a month in England and then only by exceeding the agreed limits for Army imports. The record figures for May 1944 were largely using capacity reserved for the invasion “exports”. Even so in March 1944 the estimate for May would be a backlog of 540,000 measurement tons of cargo for England in the New York Port of Embarkation and a shortage of 61 ships to move the cargo even assuming it could be unloaded in England. On top of that, as a mentioned in an earlier post whose implications I think were missed, military cargo tended to be less dense than other cargo, and it was difficult to co-ordinate movements to obtain the best use of shipping, to fill ships cargo holds at the same time as reaching their weight limits. In February 1943 for example some 93 transports sent to England had 5 million cubic feet (125,000 measurement tons) unused.
Next problem. Since everything came into western ports, it all then (in terms of AGF forces) had to be transported across England to depots established for the invasion in southeast England, by rail, which overtaxed a system never designed for such cross-country port to port runs. AAF of course was different, which added to the complication. Depots in southeast England did little to support AAF basing in the east and northeast. ASF of course was different too, since its resources had to be able to support both. By March 1944, as the British railways overloaded, 1/3 of US Army cargo was moved from the ports by road, which meant greater wear and tear on trucks and truck units already in short supply, as were the tires and fuel required to keep them on the road. In May came restrictions on civilian rail transport. The approach of the invasion put three extra loads on the railways: the export of the armies, the replacement for the coastal shipping used to support the landings, and the rerouting of cargo that would have normally used the ports the armies were using. Problematically, prewar the British railways put into service around 600 locomotives a year, but for 28 months to the end of December 1941 only 359 had been built, of which the government had requisitioned 378 of which 138 were lost in France. Thanks to holding onto older, normally retired locomotives the overall drop in numbers was only around 200, but the military also wanted locomotives for other theaters. Britain raised production of steam locomotives from 272 in 1940 to 1,050 in 1944, mainly using the Austerity design, 450 of which were in service on 14 March 1944. The US shipped around 400 locomotives to England starting in November 1943. By 28 September 1943 there were 341 in use, plus 33 in shops and 26 awaiting alterations. Apparently they were shipped needing alterations, like hand brakes, which meant they were not a complete bonus, competing with the local locomotives for repair facilities. By 15 February 1944 398 of the US locomotives were in use.
Note however too the anticipated requirement for Continental rail operations. By the end of June 1944, some 1,720 out of the expected requirements of 3,404 locomotives for continental operations (2,270 for the US forces) had arrived in England, along with 20,351 disassembled rail cars, of which 7,106 had been assembled by the end of June. It was expected the allies would have to provide some 57,000 rail cars for continental operations.
Next problem. Where does it all get stored? You see, there simply wasn't convenient acres of covered storage in the English countryside. It had to be built from scratch. In order to handle the supplies the US Army in England built just under 20 million square feet of covered storage and shops, 43.5 million square feet of open space and hard stands, storage for 173,325 tons of POL, storage for 448,000 tons of ammunition, and storage for 48,350 vehicles. This building project took about a year, from May 1943 to May 1944, and cost $668 million on construction projects in England, the Air Force used $440 million of this, troop accommodation $59.2 million, hospitals $57.2 million, depots and shops $50.8 million.
Next problem. Who builds all that? Not the British for one, since they were already fully engaged in their own works projects and did not have the manpower, funding, or construction equipment to undertake such a massive undertaking. So guess who built it? The US Army, specifically the Engineer G/S and S/S regiments that were a large part of the initial troop strength shipped to England. Has no one noticed that for the period from roughly December 1942 to September 1943 US Army ground combatant forces in England consisted of the 29th Inf Div and not much else?
Next problem. Inexperience. Some of the problems caused by simple inexperience in the Army staff and its ill-considered actions border on the farcical. For example, it took until mid 1943 for the US Army to work out and put in place a standard set of mandatory labels for cargo, what was in it and whom it was for, standard manifests followed...in 1944. The failure to do this in 1942 caused a lot of angst. In mid 1942 an example given was one ship where 30% of the cargo had no markings and 25% had no addressee and just general description, e.g. Quartermaster. This was compounded by the lack of shipping, resulting in loading ships to capacity with what was on the docks rather than send a ship out partly loaded, and the shortage of army equipment, leading to piecemeal arrivals of equipment on the docks. In September 1942 the equipment of one infantry regiment was sent to England split up between 55 ships.
The result was although the equipment was in England for the US troops already in England allocated to Torch some of the equipment had to be sent a second or even third time because it became lost somewhere in England. Mainly thanks to inadequate markings with help from an inexperienced supply system in England. This was a major issue in 1942 as equipment that could have been training troops in the US was simply "lost" for the time. [As an aside, this problem extended into 1944. When my Dad's 537th AAA AW Bn POMed at Fort Dix in February 1943, they did not turn in the 32 trailer-mounted quad-.50 Machine Gun Mounts M51 (Multiple Cal. 50 Machine-Gun Mount, M45, on Trailer Mount M17) they were supposed to have, because they did not have them. Production of the M51 trailer had just begun in August 1943 and only 2,195 were manufactured through the end of 1943, which was insufficient to equip the large number of AW battalions in existence. Worse, most of those produced were shipped to the theaters of war, except for a few used for demonstration purposes at the Antiaircraft School. As a result, battalions made do with the venerable and heavy – the gun weighed 100 pounds, its tripod 380 pounds, its 200-round ammunition chest 80 pounds, and the cooling water 20 pounds – .50 Caliber Browning water-cooled heavy machine gun.] The lack of equipment and shipping space meant the troops had to give up their equipment 30 days before the voyage and it took 80 to 120 days longer than the troops to arrive in the UK. By mid 1942 the idea of "pre-shipment", excess stocks for later use was mooted and put into practice in 1943. This had the advantage of using “spare” port capacity in England in 1943 that troops could be issued equipment on arrival that troops posted overseas could wait until the last minute to give up equipment to another unit before moving instead of giving up vehicles 30 days before departure so they could be packed. Note pre-shipment was not for all equipment, and troops still moved with a significant amount of their own equipment. Some 2,427,628 measurement tons of pre-shipment cargo was sent to England in 1943, another 1,863,629 measurement tons in the first 5 months of 1944.
Next problem. When it came to bulk fuel stocks it was a steady juggle calculating between tanker allocations and consumption. This was especially critical during the U-Boat caused "tanker shortage" of 1942. Tankers could be “black oil” or “white oil” and changing between the cargo types required an extensive tank cleaning. So it was quite possible for an excess of white products like Avgas to build up while stocks of (black) naval oil fuel went down. Fuel consumption in the UK was generally below forecasts enabling stocks to be built up when the tankers were allocated on the basis of the expected consumption. Excess stocks then built up and the result was the reallocation of the tankers to other runs. So, for example, stocks went up even as the average weekly imports fell from around 364,000 tons/week in mid 1943 to 250,000 tons/week in the first two months of 1944. The trouble was tankers being in such short supply once they were allocated to another run it was very hard to get them back, and consumption by the forces in England rose significantly in early 1944. In the period March to May 1944 weekly imports climbed to 402,000 tons but bunker fuel levels were still below the October 1943 level and stocks of “white” products, like Avgas and MT80 continued to fall. For the first time in the war Avgas consumption exceeded the forecast. The “white” fuel stocks were still below planned levels on D-Day, the result was a major increase in shipments in the middle of the year, naturally putting stocks well above the agreed levels again, some tankers were then withdrawn and the feast/famine cycle began, again. As an aside the UK oil imports in 1938 had been an average of 223,000 tons per week.
Fundamentally, to enable a June 1943 assault on German-occupied France would require the US to begin all those construction activities that historically began in January-May 1943, a year earlier in January-May 1942...except there were essentially no trained Engineer G/S and S/S regiments in existence to begin the work that early. WATCHTOWER and TORCH were essentially improvised, shoestring operations, which garnered considerable experience on what would be required to mount a much larger operation like NEPTUNE. Without them and the additional experience gained in HUSKY and AVALANCHE and the result would likely have been problematic in the extreme.