Okay Niehorster's Orbat is back up, but some links still aren't working again, but enough for our purposes here. That said since everyone is bringing up the same issues with a Quiberon landing, I'll address them all here rather than to each person individually.
German Army Order of Battle Army Group D 28 June 1942
If you haven't used this site before, the highlighted boxes are clickable. So click on 7th Army which is the main Army that would oppose this proposed early D-Day. Then click on XXV Corps which is the zone that is being hit.
We have 6th Panzer which is enroute to Stalingrad at the time of this proposed D-Day. Hitler desperately needs it there. But if he cancels that order and brings them back to France, Stalin will be pleased mightily, OTL 6th Panzer mauled the fuck out of the Soviet 5th Tank Army before being stopped short of Stalingrad. If it is instead deployed to the Quiberon area, it will learn real quickly that Panzers don't win arguments with Battleships and the early model Shermans are more than a match for its Panzer IVs and IIIs. American troops are also packing the Bazooka while the Germans have yet to deploy Panzerfaust and Panzerchreck and won't till August next year.
17th Division is not in the vicinity. 333rd is a static division spread across the Lorient Saint-Nazaire Front which includes Quiberon and asking to get chewed up piecemeal, and there is no coastal artillery present, even if they were, going by the other Amphibious Operations, they are a nuisance more than a credible threat and either BBs or Paratroopers can silence them. The Herman Goering Regiment would be gone by the start of November to the Mediterranean because that bad boy Monty hurt Rommel causing him to cry
The 202nd Panzer Regiment is under strength.
LXXXIV Corps is composed of Static Divisions and Fortress Units.
Going to the 15th Army in Normandy, LXXXI Corps is Static Divisions and coastal artillery batteries. LXXXII Corps has only the 106th Infantry Division available to move. 10th Panzer is still rebuilding from the mauling on the Ost Front it received and was barely able to scratch together a small force to send against the Dieppe Raid.
LXXXIII Corps has just one Infantry Division.
1st Army has under strength units that have to watch the Vichy French and will likely go south to ensure the Vichy Ports don't become Allied Ports, several of its Units are slated for the Ost Front where they were involved in Manstein's Kharkov Counter-Offensive. If they stay in France, Stalin won't mind, and would be delighted, Kharkov will certainly enjoy staying liberated. Also 12 Infantry Divisions transferred to the Ost Front go to France instead, heck the German Forces in the Caucasus might even go into the bag.
Luftwaffe isn't much better, with the bulk on the Ost Front and only a few hundred aircraft in France spread out and facing aircraft from Britain, the Vichy if they decide to rejoin the war, and the Aircraft defending the beach heads. While in theory, Hitler can pull aircraft from the Ost Front, Stalingrad is surrounded with the 6th Army in it and the Transports need escorts. If Hitler pulls Luftflotte 2 out of the Mediterranean, Rommel is done, the Italian Air Force is short of fuel to be much help. Pull the Aircraft from Germany, well the CBO gets easier. From Norway, well the RAF will enjoy dropping presents there. Even before Paulus got encircled, the Luftwaffe was bringing him supplies because the transport network to Stalingrad was utter shit and not helped by splitting Army Group South in two. The Luftwaffe is also trying to supply Rommel and Demyansk. Even when it had air parity, the Luftwaffe proved unable to defeat Allied Landings backed by BBs, and if float planes can operate in the presence of FW-190s as they did OTL, any German Counter-attacks are going to get busted up badly by the firepower of CAs much less BBs. Finally the Luftwaffe has very little AShW capability and the glide bombs of 43 don't exist yet, tactics that worked against British Convoys in the early stage of the war are suicidal against the sheer Flak the USN can throw out and that's before we consider the carriers.
Since this proposed D-Day has Ranger, CVE 26, discounting CVE 28 as its ferrying 75 P-40s, CVE 27, CVE 29, CV 47, CVE D 14, CVE D 37, CVE I.49, CV 67, and CV 38, which gives the Allies local air superiority, especially as the British are now deploying Seafires. Plus, and I will give the British rare credit, their carrier pilots are trained for night operations and did in fact launch numerous successful night ops during WW2 a capability no other side was able to excel at. This also means the Allies can make it even harder for the Germans to respond by air-land-sea. Since the P-40s can fly from Britain once grass strips are ready, CVE 28 can take on F4Fs instead to boost the Carrier Air Power. Once grass strips are ready for the P-40s they can fly in and begin providing air cover and escorts for Allied Bombers flying from Britain and are still competitive against German fighters of this period and have good operational range that is double that of spitfires. Using the circle function of Google Pro, their combat range enables them to operate over Paris and as far as Frankfurt if I'm reading the operational range right for the P-40E and assuming they are operating from Belle Island. If I'm reading it wrong and it half that, then still Paris is in range which means German Forces responding to the Invasion are getting pounded from the air as far forward as Paris as they move up. Given the French rail network runs through Paris with no Parallel tracks along the coast, any German counter-attack has to stage from Paris. As the air facilities expand the XII Fighter Group can move in and further improve the Allied Air Superiority over the Bay of Biscay and Brittany. XII Bomber can remain safely in Britain and conduct operations till a breakout occurs to let them stage in France.
Kriegsmarine can have 30 submarines top in the area, which is not conductive to U-Boat operations, facing a double screen of destroyers and minefields, plus Allied Air Patrols. The Schnellbootes are a nuisance at best. Given the massed fleet they face in this scenario, the best they can do is fire torpedoes at max range like they did on D-Day, and run for it, plus they are based at Le Havre, which is on the Channel Coast. If the Allies seize Groix Island, either by a landing force or a Paradrop or both in combination, they can emplace artillery and aircraft to block the Lorient off, rendering it useless to the Nazis which helps contain the U-Boat threat. From Belle Island to Quiberon City is 13.5 kilometers which can be mined off to prevent Submarines making an approach from that direction. An outer destroyer screen can be placed between Belle Island and Guerande which is roughly 39 kilometers long with an inner screen anchored of the small islands. Any submarines trying to force the screen will die, as they have to surface in order to attack. Donitz simply doesn't have the replacements yet and may in fact order his subs to abandon the Bay of Biscay if the Allies gain a successful lodgement which in turn means Allied ASW Forces are blocking the Lorient and Saint Nazaire Ports to operations, which also greatly helps winning the battle of the Atlantic as well by denying the Germans two bases with which to break into the Atlantic. The heavy German Naval Units are being repaired and even if available would have to traverse the Channel or North Sea and be open season to the British Home Fleet. If Donitz decides to fight it out or Hitler orders him to, then it won't make a difference, the U-Flaks aren't ready yet, and the Naval Commitment of the Allies makes the Bay of Biscay a death trap for German U-Boats which consist of the Type VII and IX, neither of which are survivable against the Allies in the Bay of Biscay, the XXI have yet to be built and won't till next year and only in small numbers to begin with. So the German Naval Defenses are not a credible deterrent.
Even if the Kriegsmarine were to spot the Invasion Force, the Invasion Troop Convoys are moving at 12 knots. That's double of a Merchant Convoy and heavily escorted. The U-Boats have to surface to intercept and that is suicide. No troop ships were sunk making the Atlantic Crossing and few troop ships were ever sunk, and only one by submarine due to a lack of escorts in 1940, the others ate glide bombs. Also Huff-Duff was well established by this point with regular ASW patrols in the Bay of Biscay and in the waters of the Bay of Biscay, the U-Boats would have no hiding places. If they surface to re-charge their batteries, doom on them. If they surface to make an attack, its death to them. If they try to sneak past the Destroyer pickets and minefields, it will be their destruction. Even submerged, they will be seen from the air due the shallowness of the bay, which varies between 31 meters and 91 meters, 100 feet and 300 feet if you absolutely insist on Imperial measurements.
Nor would mines be an impediment. The magnetic mines had already been defeated by the degaussing process in 1940, and no Allied Landing failed because of minefields. Nor do the Germans have the bottom contact mine defenses (basically modified AT Mines attached to steel girders) used at Normandy, in this area. Also the Germans had big problems mining just the Channel, I doubt they have sufficient resources to mine Quiberon Bay much less Saint Nazaire which was successfully raided in 42 with no problems from minefields.
No matter how you look at it, Hitler's problem with a Quiberon D-Day Landing in November of 42 are unsolvable and General Marshal was correct to push for an immediate French Invasion while the cream of the German Army was largely tied up elsewhere. And the Vichy French could be in a position to switch sides and open the Southern Ports and hold them long enough for Allied Reinforcements to arrive and breakout from them at the very least. In the best case scenario the Vichy could mobilize their off-the-book units fast enough to join their official 50,000 strong forces in Southern France to hold back Nazi Forces till their North Africa Army which had substantial armor units to return and thus open another Front.
Now back to the proposal, what is envisioned is using the same
Torch Force for this ATL D-Day.
Now Patton's II Corps already contains more Tanks than the Germans have in all of France. Granted they are majority Stuarts, but they initially face no German Panzers and the 333rd has limited AT capability, and all things considered, the M3 was a combat success in the Cavalry and Infantry Fire Support role and given the opposition they face they are more than adequate for the job leaving the Shermans, Grants, and M10s free to handle German Armor once they show up, and for sake of argument lets say its Rause's 6th Panzer, who instead of mauling 5th Tank Army in the USSR goes gunning for Patton. As for 5th Tank Army, I think it can find a lonely German Division to kick in the ass and throw into a river instead of getting kicked in the ass and thrown into a river by 6th Panzer as OTL.
End result is the same as all other German attacks on Allied Invasion Beachheads led by Allied Commanders not afraid to bring the big guns. Naval Gunfire support breaks up Rause's attack, M10s from prepared positions pick off his tanks, then M4s maneuver around them, exploiting their gyro-stabilizers which enable their gunners, who have padded periscopes to enable them to use them while the tank is moving, to keep the gun on their target so when the tank stops they can swiftly begin firing. German tank gunners don't have padded periscopes, or a gyro-stabilizer, or a powered turret, so they have to wait till their tank stops before they can scan for and engage targets, hence why US Sherman Units mopped the floor with them OTL. And I haven't gotten to Allied air and artillery assets, especially the artillery assets which broke up many German attacks.
Since Panthers won't appear till mid 43 in numbers, and despite Nazi Propaganda they lost lopsidedly to Sherman 75s in actual combat, even when numbers were equal, the American Armor Forces should have no problem eating Panzer IIIs and IVs. Tigers are too small in number and deployed elsewhere, and if Hitler pulls them to France, other Allies will leap for joy. Contrary to popular belief, the US Army is already considering a 76mm gunned Sherman and getting ready to test the concept and a few were even deployed for D-Day 44. This was before they even knew of Panthers.
Central Task Force can be used to reinforce the lodgement and take defensive positions once Patton opens the door.
Eastern Task Force can be used for the small Islands in the area, securing them for use as air bases and sea defense against submarines and small craft before moving in to reinforce the lodgement.
The British can feed their units in as space opens and they have in addition 12 Divisions in Britain itself that are immediately available as reinforcements.
Additional Reinforcements can follow on to expand the lodgement and breakout in 43 along Northern France with subsidiary landings conducted along the North French Coasts against light resistance, because the defenses of 44 don't exist yet and were largely incomplete even in 44.
Landing wise, it should be even easier than Torch which was done over an open sea with very rough surf as opposed to a sheltered anchorage that Quiberon Bay is. Lets see the Torch Landings resulted in half the landing craft being incapacitated for various reasons, though the vast majority were repaired and returned to service in time for Sicily. With Quiberon Bay being sheltered, the losses would be far less and the landing far more orderly with the three ports in the area, the Allies can easily supply their forces and build new piers to expand the port capacity.
The more one looks at this scenario the more its doable, and given the German disposition of forces in 42, they simply can't stop a landing in this area, and more than likely would swiftly lose Lorient and Saint-Nazaire if the Allies are aggressive enough to press the numerical advantage they will have initially in the two week window they have before Hitler can bring up substantial forces capable of combat, assuming they aren't sent to deal with the Vichy. If Rennes rises up against the Germans, then the problem for Hitler increases even further with having to do a city fight against the French Resistance within range of Allied support. There is also an active communist resistance group of the Francs-Tireurs et Partisans Français in Nantes which is engaged in active guerrilla warfare at this time and recently assassinated a German Colonel, which causes more problems for Hitler in countering the lodgement.
There is really no way for the Germans to stop an Allied Lodgement and breakout, if they ignore the Vichy, they can bring back its North African Army and hit the Germans in the flanks and open its ports to the Allies. If they send forces to subdue the Vichy and they fight back and open their ports to the Allies, they face a two front fight and the French Fleet. If they pull aircraft and forces from the Ost Front, it will collapse even faster with a worse disaster than the OTL Stalingrad debacle. Nor would the Italians be much help as its fleet lacks fuel for major combat operations and has the pesky Royal Navy Mediterranean Fleet and Free French Fleet to consider. The best Italian Forces are on the Ost Front, Africa, and the Balkans too where they are getting ground up.
Hitler can't even order 6th Army to break out if he wanted to. Its a leg mobile Army that advanced on Stalingrad with bicycles. People who say this Army can escape Stalingrad have yet to explain how these leg mobile infantrymen will fare out in the open, exposed to the Mechanized Soviet Forces, when at least in the city they have shelter and protected fighting positions. Even before the Soviets hit Paulus, his Army was having massive supply problems, XLVIII Panzer Corps had on paper a 100 Tanks, but only 28 were capable of fighting due to lack of fuel and ammo. Oh and rats ate the electric lines of their tanks as well, those dirty commie rats
The other German Panzer Divisions had the same problem with a lack of fuel and ammo to move. The 10,000 trucks were down due to lack of spares and fuel. German soldiers were even starving to death in the fight well before the Soviet Offensive because they didn't have the right rations for the Russian Winter! Mauser bolts were jamming in the cold reducing their firing rates as the German's gun oil wasn't suitable for the cold and they couldn't mix it with gasoline like Soviet Troops could to make the gun oil work, as they didn't have the gasoline to spare. So the stand fast order was actually smart as it tied down six Soviet Armies in reducing the pocket in city fighting, Armies that would have been freed up if the 6th Army had tried to bolt for it. The Soviets knew this, its why they offered Paulus honorable surrender terms, they wanted their six Armies driving to Rostov and Kharkov instead of tied down in city fighting.
In a Quiberon scenario, Paulus is even more fucked. Divisions sent to the Ost Front are now going to France, which means Manstein is not even thinking of Winter Storm, he is thinking if he can even hold Rostov so German Army Group B can escape. Which means he is abandoning air fields needed to supply him with even a trickle of goods. This means the Soviets have fewer German Units to fight and can amass more local superiority. So Paulus likely folds faster freeing up the six Armies tied up with him to be used elsewhere to devastating effect. Operation Mars was also going on at this time, and if Stalin perceives that by throwing in his Jupiter Reserves, he can force a break through, he'll do so. Even if they don't garner a breakthrough, they'll complicate German Operations in the Ost Front even further, making for further Soviet Gains in the Ukraine.
Nor does the "Greeness" of US Forces hinder it, because they face forces just as green. In fact their Infantry Divisions pack just as many tanks as a German Panzer Division thanks to attachments of independent Tank Battalions to them and their firepower is far greater. At this time period, the Germans have yet to field the MG-42 in large numbers and US Troops were and will counter by jury rigging M1919A4 MGs to be used in the same manner as the MG-42. Some GIs even rested the barrel in the crooks of their arms and fired from the hip (don't recommend doing that, the barrel gets super hot, even though it got several GIs a CMOH), while others used a series of straps to fire it on the move. US troops also have a communications advantage at the tactical level due to their SCR-536 and SCR-300 which was VHF FM radio which the Germans didn't have an equivalent to. Though not yet standard, the SCR-508 was also in service as well on the M4s and is also an FM radio. So the US Forces have a command, communications, and control advantage over the Germans in knowing where their company and platoon formations were.
Nor can US Officers leading the troops ashore can be considered green. Many fought in WW1 or Brush Fire Wars in the 20s and 30s, and many of these officers had spent two years training together with their troops while the foes they face are Static Divisions of questionable quality, reformed units with new recruits, and spread out across France and needing to concentrate forces first.
The only thing that will clinch this is the NOAA data from November 1942 for the area. If the Bay remained calm enough for landing operations which due to the Iselets it would be, then its a go. The Nazi scumbags can't stop it, the Allied Local Superiority would be far too great. Salerno was far better defended and the Nazis knew it was coming and still lost.
And if US TF 34 could survive a full blown gale in which a minesweeper had a 42 degree rolls without capsizing, enroute to Morocco for Operation Torch, conducted landing operations in a 4.752 meter (15 feet) surf that temporarily wrecked a third of the landing craft under combat conditions against the Vichy French who sortied an incomplete battleship to oppose the landing, Quiberon Bay would definitely be a cakewalk being far weaker in defenses.