Exactly Carl.Even I understood that from the start LOL.

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For the first time I have seen "History" at close quarters,and I know that its actual process is very different from what is presented to Posterity. - WWI General Max Hoffman.

oops...I did read the post..but it was a while back...sorry....


P.S. Dam it...I thought I had a valid point

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Facta non verba. "Deeds, not words"

Dont sweat it. Dig into the literature on this period of the war, Dec 1941 thru mid 1943. There are some things that would trouble Gardners Sledgehammer, but aside from the water conditions inside Quiberon Bay I've not seen them raised here.

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Please bear with me T.A, but I still have this U-boat question on my mind.

Attached to this post is a map scanned from Winston Curchill's "The Second World War", "Hinge of Fate", page 128.

It shows that most of the allied tonnage sunk by German U-boats in the timeframe Aug. 1932 to May 1943 was in the North Atlantic.

Let's hear what Coast Guard officer John Waters has to say about the winter 1942/43:
Quorte:
"In that terrible winter, the weather would break records of fifty-five years standing, and 116 days out of 140 would see storms of gale force or greater on the northern ocean. Many years and dozens of storms later, veteran seamen would still hark back to the storms of that winter to define the superlatives of the weather at sea."

Even under these appalling weather conditions and despite escort screens, German U-boats sunk an all time high number of allied tonnage during the winter.

I assume it was common practise to proceed at utmost speed when crossing the Atlantic to avoid the U-boats.
A convoy proceeding at 14 knots in the Bay of Biscay would therefore be a piece of cake for the veteran German U-boat captains used to far worse conditions.

But let's say that the convoys of operation "Sledgehammer" are let into Quiberon Bay undisturbed.
Now the U-boats can seal off the Bay of Biscay preventing further supplies to the landing force.
The carriers and the battleships will sooner or later run out of fuel and ammo, and the landing force will have no cover from naval artillery and planes.

The by now reinforced German land forces will push forward and eliminate the allied bridgehead.
This operation has been so costly to the allies in loss of troops and equipment that in reality they end up with their back broken, and further landing operations are postponed indefinitely.

In the European Theater of Operation there will now be only one star in the show, the Red Star.
The Soviets will "liberate" all of Europe, perhaps except the British Isles.

RAM

Attached Images

1942-43 001.jpg (171.0 KB, 6 views)

I posted this on page 3 of this thread. I guess it is worth reposting:

Taking just the U-boat part of this for the moment.

Do you know what the handful of U-boats that might reach the convoys would be facing?!

First, the most U-boats to get into a single wolfpack was 9 during the war. Most of the boats would be unable to make the convoy area before it arrived at its destination.
That aside, those arriving to attempt to take on the convoy would face a two ring destroyer screen operating around the convoy. These two rings consist of 40 destroyers with both radar and sonar making a concerted sweep of the convoy path.
There are 5 carriers present and they are flying ASW patrols around and above the convoy as well.
This makes surface approaches virtually impossible. Attacking submerged is purely a matter of luck. The boat would have to have submerged in front of the intended path of the convoy and be on its random zig-zag pattern course. It would then have to not be detected by the two screens that drive over its position. The sub would also have to make it past the inner escort ring with another 9 destroyers and, if daytime, it would have to be suffiently submerged to avoid aerial detection too.
The entire convoy covered an area about 20 x 30 miles in size. Making things more difficult, the convoy speed is 14 knots. This is well above the submerged U-boat speed so the only viable way to get positioned is a surface approach. Given US use of SG and SC radar along with the presence of aircraft a surface approach by day is nearly suicidial. By night the Germans are operating blind. No radar, no means of seeing where the convoy has moved. Blind luck is all they have to stumble on the right position and course.
In either case, just having to dive because a destroyer or aircraft approaches is sufficent to cause the U-boat to lose any chance of an attack. A one hour delay due to submerging means having to cruise at high speed on the surface for 4 to 6 hours just to regain position.

Basically, the U-boat threat is greatly overrated against a high speed military convoy. That's the historical side of the crossing.

As for the threat in the Bay of Biscay:

I have actually been gaming this scenario out now off and on for over a week. Lorient would have to be abandoned as a U-boat base within days of the landings simply because it would now be under intermittent artillery fire and the threat of loss is potentially imminent. St. Naziare would likewise have to be abandoned within weeks due to increasing Allied air presence and the much heavier mining of the approaches now far more easily accomplished with closer air fields in operation.
U-boats cannot successfully operate in Quiberon bay itself simply due to the shallowness of the water.

In fact, in trying to find a way for the Allies to lose this scenario I have so far only come up with one: They get over zealous with their initial success and press forward into France rather than dig in and defend the beachhead.
I would particularly note that the Germans in the first 72 hours cannot even completely contain the beachhead. They don't have the troops in position to do it. The best they can initially do is shore up the shoulders and wait for reinforcements. This is where the Allies can get into trouble. Facing little or no opposition to their front, they press forward rather than hold their positions inland about 6 to 8 miles from the beaches.
German panzer units rushing to the front can then cut these advancing columns off and defeat them in detail.
If the Allies dig in instead the panzer units are forced into just filling the line at first to make a complete defense. This dissipates their fighting power sufficently that they are just defensive units like the ones they face. They will also arrive peicemeal and be put into the line that way further diluting their combat power.
To make matters worse for the Germans they simply don't have the necessary divisions in France (or elsewhere) to throw against the Allied beachhead in sufficent force to defeat it. This will take them weeks to even make an attempt at, just as it did at Anzio.

A few other points on submarines operating aganst a Allied fleet off the French coast.

The British long range aircraft operating in anti sub patrols ahd already made it very dangerous for a sub to surface in day light in the Biscay waters. Donetz remarked in mid 1942 that they had to transit that area and beyond submerged due to the air activity.

This is in range of the light antisubmarine surface ships which had to operate close to their home ports. Between these and the aircraft patrols the German submarines had suffered unacceptable losses near Britian and were making their convoy interceptions in the mid Atlantic where losses were somewhat less.

Add the usual air patrols and patrols of the shorter range ASW ships to the invasion fleet escourts.

The north third of Biscay is on the continental shelf and the depth decrease to above 50 fathoms, with many shoals or banks of less than 20 fathoms. It is not the ideal water for submarines.

Well in 1942 a bit over 9% of the cargo destined for Britian across the North Atlantic was lost to submarines. In 1943 that drops to a bit over 3% by the middle of the year.

That was the peak of losses to the submarines. Despite the loss of the Enigma radio message deycrypts and the German penetration of the British convoy codes for many weeks cargo ship losses begain to decline in early 1943. And, the loss of submarines beain to increase. I expect trying to operate the submarines in the shallow coastal waters, against a dense ASW air and sea patrol would both decrease the Allied ship losses, and accelerate the submarine losses.

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I cant recall, what game system are you using? Is the scale large enough to include the possible effects of Vichy France? and, does the time scale allow playing this into the end of 1943?

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Its a modified version of GDW's Avalanche game on the Salerno landings. I chose it because it contains all of the elements for doing an amphibious assault. I have only been trying out the first couple of weeks or so of the landing.
My intent was to demonstrate that the Allies could get ashore and stay there.

The scenario I'm using right now is an initial landing of 3 US Infantry Divisions, one Canadian and one British along with one British tank brigade.
The Canadians land just south of Etel with the British landing just south of them.
The US lands one regiment on the pennsula to Quiberon and the rest of that division near Carnac. A second US division lands between there and the entry to the Morbihan Gulf. The third lands on the Presqu Ile de Rhuys east of Arzon.
Prior to the main landing the 82nd AB parachutes in one regiment just south and east between Pluvigner and Auray.
Belle Isle is assaulted by a ranger and commando battalion along with a battalion of the 509th dropped in daylight.
The defending Germans initally are a bit more than one regiment of the 333rd Infantry that is spread here an there in battalion and company strength.

The same thing happens initially each time.

The Canadians swing north and are stopped just outside Lorient by the 17th Infantry Division. The British swing inland on their flank and link up with the 82nd. They hold a line from roughly Landevant to east of Pluvigner. By late day on D+1 they are facing the 257th Infantry Division and are set for a defense.
The US moves inland with the only real heavy fighting being pushing the Germans out of Vannes. The 333rd just does not have sufficent strength to take on a full division and stop a second one from potentially cutting their troops off in Vannes.
The result is that by D+1 the US is holding a line from Pluvigner to just north of Vannes on a ridgeline that runs along that line and then to roughly east of Theix and south to Ambon. The remains of the 333rd is holding the line from Ambon to just east of Vannes.

By D+3 the Allies have additionally landed 2 US infantry divisions, 2 armored divisions, one British infantry division and two British tank brigades.

The Germans reinforce their front but the first two panzer divisions arriving starting on am D+3 immediately go into the line to hold between Pluvigner and Vannes where there is little or nothing defending. Their panzergrenadiers and Aufklarungs battalion arrive first having driven to the front. The panzers arrive about a day later (due to having to go by train).

Some variants:

The US tries to push out of the beachhead. I've done this with the new arrivals on D+2 and 3. The armored divisions push into France on the N767 or try to flank the 257th at Pluvigner. Either way they end up getting hit piecemeal by the German panzer divisions and torn up. Of course, this doesn't do the panzer divisions much good as they too suffer from the fighting. But, the US takes a bloody nose and has to withdraw leaving the field to the Germans.
Another try was made to push an armored division to take St. Nazaire. This ends up badly as the 333rd falls back on the city and has the advantage of heavy woods and swampy ground in the Briere Nature Reserve. Basically its too far and too many natural obstacles to be successful.

If the Allies stay in place their naval fire support and initial material superiority pretty much makes it one sided attrition for the Germans. The Germans simply cannot go on the attack (they are too weak) and cannot leave. So, Allied artillery and naval gunfire pound the snot out of unit after unit.

In the air the Allies have some problems. Their naval air power is sufficent for air support and fending off bombers but it cannot take on German fighters. While this part of the system is somewhat abstract what it does show is that the Germans cannot put enough airpower into the area to really effect ground combat. They can score a few hits on ships forcing their withdrawal due to damage.
They also cannot afford a drawn out attrition battle in the air. They may give better than they take but they cannot take alot before they don't have anything left.

I really haven't looked at the Vichy French situation. But, if they throw in with the Allies this is only to the detriment of the Germans big time. The Germans literally don't have anything to throw into taking Vichy France. They are too busy trying to just pin the Allies in their beachhead. As Bordeaux-Merignac is a major Luftwaffe base this would have to be almost certainly abandoned to the French if they did throw in. That throws a major monkey wrench in bomber operations.

That's a quick synopsis. I'm working on a more detailed one but it is taking some time to do.

Looks like the next step at this scale is to make some accurate estimates what size army the Quiberon beaches can actually supply. To mean anythig stratigicaly the Allied army must be strong enough to secure the Breton penensula, then the ports. That brings us back to what sort of defense the ports had facing inland, and what the cargo capacities of these ports are.

I suspose you read my posts on the subject of supply on the Axis Hist Forum?

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Of course. I would think that the key question is can the Allies take Lorient? It would solve most of their supply problems. The small ports they would hold initially might not be enough. But, they have alot of sheltered water and could use landing craft to supplement those.
I know by the end of 1942 that most of the construction on the Atlantic Wall at Lorient is going into the sub pens. This is tying up nearly 2000 construction workers and army engineers at the time. I would think the construction would be abandoned and these workers put to use building field fortifications immediately. However, other than whatever French coastal batteries existed in the area there is really little real construction going on what would become the 1944 version of the Wall.

After Lorient is Brest, which is susposedly the real money maker for the Breton ports. At least the Overlord planners thought so. there were already old French fortiifications protecting Brest, tho I've no clue how strong they were on the inland side. Did Lorient have anything like those?

Add as per my earlier question, was there a all weather airfield anywhere near Lorient or Vannes?

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I'm not sure on the French fortifications but I would suspect only coastal defenses were present.

As for the all weather air field, this is irrelevant. The US will have landed three full engineer regiments by D+7 and they can build one (or more) using landing mats if necessary. This represents the same manpower and equipment that built the Alcan highway in under a year. This doesn't include the divisional engineering battalions or several battalions of shore engineers for the beaches (all original to Torch too).

I would not call it irellevant. Certainly not in the short run as capturing such a place in the first week increases the availble airfield surface much faster than the engineers build it from scratch, and if there is enough captured leaves part of the construction battalions free for other tasks. In the grand stratigic picture a couple weeks may not make much difference, as the commander of this invasion I'd be happier having more fighter groups on the spot sooner. And, the quicker more fighters are based in Brittiany the less thoese related issues are relevant, know what I mean

The only refrence I have for this is a map of some of the airfields the Luftwaffe used. It shows one facility at Rennes, one near St Nazierre or Nantes, and one on the far west end of the penensula near Brest. Since this map does not show the auxillary airfields or those used by the aircraft maintinance units I'm assuming it may not show everything available in Brittiany.

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Sorry about the delay, but I have this thing called work that consumes me completely from time to time, and my dream of an early retirement seems more distant than ever.
3rd quarter ended yesterday, and at the end of each quarter we have to sit down to figure out some numbers that will please the big bosses at the head office.

Now to the topic:
It wasn't until 1943 that the Allies got control of the activity in the bay of Biscay after several offensives carried out by RAF Coastal Command 19 Group:

Derange 4/13-6/6 1943
Musketry & Seaslug 6/4-8/12 1943
Percussion 8/21-9/21 1943

That wouldn't have helped operation "Sledgehammer" much in it's initial phase.

During this winter the number of U-boats in the Atlantic increased steadily, and as late as March 1943 the Uboat force, notwithstanding the unfavorable weather in the Atlantic, ran up with a noteworthy record of sinkings: 84 merchant ships for 505 000 tons in the Atlantic alone.

The operation "Sledgehammer" would have been a premature move in 1942 and the Allied knew it, that's why it never happened.

RAM

Are these 'bosses' accountants? A wise old prefessor of econmics remarked to me: "The trouble with accountants is they think their numbers have something to do with reality.

Depends on how much 'control' is control. The German perception seems to be the Bay of Biscay was a increasinly dangerous place in 1942, because of the ASW aircraft. Unlike the Mid Atlantic where the Allies did not effective aircover until far into 1943.

Certainly, but that does not mean eisting ASW operations would not be effective as they were, or that additional ASW operations would not be organized to directly support the amphib. fleet.

Several things were going on here. The two most important were in signals intel. The Germans broke the BRitish convoy code used for the North Atlantic convys. The desire to take advantage of this is one of the reasons the submarines on patrol surged in those months. Second the British lost their entry into the radio encryption used by the German subs. in the North Atlantic.

To reproduce the the increase of ships lost in the late winter/spiring of 1943 near this hypothetical Breton area the problem of ASW air patrols, denser sea patrols by smaller ASW ships, shallower water over the continental shelf, and different radio codes or encryption used by the combat fleets from the convoys.

It has been proposed the Allied invasion fleet would suffer catastophic losses by a huge surge of German submarines. With the much denser Allied ASW and other less favorable conditions near the Breton penensula I dont see how catastrophic losses are possible. A effort to concentrate the submaarines takes them from their most advantageous patrol are, in the Mid Atlantic, to a area where they are against a stronger ASW defense in less advantageous seas. This might actually be to the Allies advantage in sinking more submarines.

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I tend to agree.

The US simply didn't have the man power or air power available in early 1942 Torch was less than 80,000 troops. There were four more divisions sitting in England and 17 commonwealth divisions. This might have proved enough but remember ITaly was still in the war as was the Vichy Navy and Germany had 1,500 aircraft in theatre not including the German Units in Italy and the Italian airforce.

The allies lacked the logistics to support the landing in 1942 and the French would have resisted even if only initially. The Southern Ports were fortified because they had been a military front in the century up to 1940.

There were intact railway networks that would have allowed the shipment of battle hardened units straight into the beach head area. Given the ability to build up their forces faster than the limited allied landing capacity and given Axis air superiority over the battle field and given the distance from a friendly base the landing idea looks like a disaster waiting to happen.

The under belly theory is a derided one now but the landings in Italy tied down a million German troops in Italy and the Balkans for the rest of the war. To replace the surrendered Italian army in Italy and the Balkans. Realistically the choice was to sit in Britain and do nothing. US mobilisation didn't fully swing into action till late 1943 .