WI Operation Sledgehammer instead of Overlord?

Sledgehammer was an invasion plan drawn up in 1942 by the Allies to invade mainland Europe through france in the spring or summer of 1943.

If that came to fruition what would have been the outcome on the war? I assume a bigger and longer western front emerging.
 
Sledgehammer was an invasion plan drawn up in 1942 by the Allies to invade mainland Europe through france in the spring or summer of 1943.

If that came to fruition what would have been the outcome on the war? I assume a bigger and longer western front emerging.

This can only happen with an earlier victory in the battle of the Atlantic which was won in May 1943 OTL

Perhaps the Italians are harder hit in the med earlier - a bigger better Op Judgement + malta reinforced earlier results in North Africa falling to the commonwealth forces earlier and King is better prepared and the 2nd happy time is not as happy this time round - More VLR B24s are freed up as VLR MPAs earlier (even as late as march 1943 they were barely into double figures (120 Sqn RAF) and the ones assigned to the USN were everywhere the Uboats were not).

Basically the Uboats have to be defeated mid 42

Op Husky would have to be chopped and more LCs would need to be sent to the ETO earlier possibly at the expense of Pacific ops?
 
A lot of questions about 1943. It may not have much to do with reality, but if you can make it stick on the game board it usually sets the end of the war well forward. The defense has difficulty coping with a larger and more difficult western front than existed OTL in Italy. In about every scenario the more ground forces the Allies place against the enemy the faster the defense weakens & we get to the Rhine river and 16 year old VolksSturm.
 
Sledgehammer was an invasion plan drawn up in 1942 by the Allies to invade mainland Europe through france in the spring or summer of 1943. ...

''SLEDGEHAMMER' covered multiple invasion plans, including three plans labeled RANKIN I, II, III. They were contingent on several changes in circumstances on the continent. One was a emergency attack were the Red Army to get into trouble. The RANKIN plans were contingent on the defenses in the west being weakend to manageable levels. Specifically a coup de main with airborne and commandos at a port.

There is a 'story'' long circulating that the SLEDGEHAMMER, ROUNDUP, and related plans were crazy ideas pushed by Marshal or other unnamed Yanks. So far the evidence I've seen is the bulk of the work on these plans and actual preparation were made by the Brits. The US Army did not until SHAEF was formed have a significant operational ground forces or planning staff in the UK. Most of the 1942/43 planning was by the Brits. The single US corps present had a subordinate role.
 
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Sledgehammer was an invasion plan drawn up in 1942 by the Allies to invade mainland Europe through france in the spring or summer of 1943.

Up to a point...

Sledgehammer was an autumn 1942 invasion; Roundup was a 1943 landing, but even military and political leaders at the time got confused about the names.

If that came to fruition what would have been the outcome on the war? I assume a bigger and longer western front emerging.

Sledgehammer would have been contained in the Cotentin peninsula and would be the focus for a very long bloody battle on land, sea and air.

Roundup was feasible and could have shortened the war in Europe, but the buildup needed to support a US Army Group in combat would have slowed early US response in the Pacific (maybe butterflying Guadalcanal).
 
Probablly not affecting 'Guadalcanal', theres a reason it was nicknamed operation shoestring. But, a huge number of things elsewhere in 1942 & 43 can be ditched to underwrite Op ROUNDUP, or whatever flavor of European invasion trips ones trigger. The follow up operations to OP WATCHTOWER in the South Pacific are a add on to Allied strategy that could be reduced to diversions. Ditto for the post TORCH operations in Africa. Let Rommel blitzkrieg all the way to Casablanca. Its a strategic dead end, and unlikely to happen anyway. The Axis supplying a army group in Africa thru all of 1943 is near as good a losing a AG in Africa halfway thru that year, and even better if the Allies are reinforcing a AG in Paris & not Medjeb al Bab. The USSR leaders complained about a lack of a Second Front. They can have with a reduction in Lend lease shipments. The list goes on.

A bit of focus on preparing for a cross Channel attack can result in things like substantially more cargo ships to execute a revived Op BOLERO, or ASW escorts to escort them, or VLR aircraft to ride high cover, ect.. ect..
 

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A lot of questions about 1943. It may not have much to do with reality, but if you can make it stick on the game board it usually sets the end of the war well forward. The defense has difficulty coping with a larger and more difficult western front than existed OTL in Italy. In about every scenario the more ground forces the Allies place against the enemy the faster the defense weakens & we get to the Rhine river and 16 year old VolksSturm.
If there is no Italian Front, then Italy stays in the war and saves the Germans dozens of divisions to use elsewhere, including at least a dozen very high quality ones. Which means that France gets a LOT bloodier from the Wallies, as the Germans could concentrate on one front and have the Italians handle most of the Mediterranean themselves.

Probablly not affecting 'Guadalcanal', theres a reason it was nicknamed operation shoestring. But, a huge number of things elsewhere in 1942 & 43 can be ditched to underwrite Op ROUNDUP, or whatever flavor of European invasion trips ones trigger. The follow up operations to OP WATCHTOWER in the South Pacific are a add on to Allied strategy that could be reduced to diversions. Ditto for the post TORCH operations in Africa. Let Rommel blitzkrieg all the way to Casablanca. Its a strategic dead end, and unlikely to happen anyway. The Axis supplying a army group in Africa thru all of 1943 is near as good a losing a AG in Africa halfway thru that year, and even better if the Allies are reinforcing a AG in Paris & not Medjeb al Bab. The USSR leaders complained about a lack of a Second Front. They can have with a reduction in Lend lease shipments. The list goes on.

A bit of focus on preparing for a cross Channel attack can result in things like substantially more cargo ships to execute a revived Op BOLERO, or ASW escorts to escort them, or VLR aircraft to ride high cover, ect.. ect..
No Torch means 8th Army is tied down in the Mediterranean and the Axis save VAST resources in the critical winter 1942-43 period, including the 40% of the Luftwaffe lost to maintain Tunisia. No extra German forces if Rommel isn't wiped out means a lot of savings to use in France...not sure this is actually better for the Wallies, especially if it butterflies Zitadelle.

The Wallies benefitted quite a bit from the periphery strategy and the Axis suffered disproportionately for it due to their problems of supplying the theater out of Europe. Even though Italy proved to be a 'tough old gut' instead of 'soft underbelly' knocking Italy out of the war was well worth the cost of a difficult front. Dispersion hurt the Germans much more than the Allies as well.
 
I did not waive away Op TORCH, or a earlier GYMNAST op, or any other variation. Did not specifically exclude those, as theres many other efforts of 1943 that can be reduced without losing WWII for the Allies. There are some strategic advantages to bringing over the French NW Africa colonies and reopening the Mediterranean to Allied cargo ships. (Note: that occurred in June 1942, before Sicilly was attacked.)

In 1943 the Germans lost 68% of their total aircraft lost in the ETO/MTO. I cant see that changing much if the air battles are predominately over one vs another bit of sky. OTL the Axis or Germans cut those losses by three times breaking off the air campaigns over Tunisia, Sicilly, and southern Italy. Would they break off a air battle over France if it leaves a Allied enclave unmolested. This has the potential of draining the German air force faster if the decision is made to contest the air longer.
 
Carl, didn't you post a link a while ago to a study by G. Michael Giumarra comparing D-Day 1942 and D-Day 1944? I've got the PDF but don't have the link. This study is a very good analysis about Sledgehammer and gives a lot of advantages the Allies would have in doing an early invasion of the continent, and several difficulties that could arise.

This was a very interesting read, and would probably help in this discussion if anyone can find the link.
 

Deleted member 1487

I did not waive away Op TORCH, or a earlier GYMNAST op, or any other variation. Did not specifically exclude those, as theres many other efforts of 1943 that can be reduced without losing WWII for the Allies. There are some strategic advantages to bringing over the French NW Africa colonies and reopening the Mediterranean to Allied cargo ships. (Note: that occurred in June 1942, before Sicilly was attacked.)

In 1943 the Germans lost 68% of their total aircraft lost in the ETO/MTO. I cant see that changing much if the air battles are predominately over one vs another bit of sky. OTL the Axis or Germans cut those losses by three times breaking off the air campaigns over Tunisia, Sicilly, and southern Italy. Would they break off a air battle over France if it leaves a Allied enclave unmolested. This has the potential of draining the German air force faster if the decision is made to contest the air longer.
Fine. That still leaves Italy in the war, Germany with only limited commitment to the Mediterranean, and the bulk of their reserves available for France. Depending on when it comes, especially if it proceeds Kursk, then the Wallies face a concentrated Axis response to the invasion of the continent. More and better forces than they faced in 1944 in France in fact once it is clear that the Wallies are only moving on France in 1943 and leaving Italy alone. Plus the Luftwaffe hasn't been defeated yet and in fact did pretty well for itself in late 1943 in France/Germany, PLUTO isn't ready, neither are the Mulberries, and the Wallied air forces aren't as strong as they'd be in Summer 1944 yet either. And the German oil supply isn't destroyed yet. OTL Transportation Plan for the run up to D-day wouldn't be possible either.

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The point I'm getting at is that an invasion of France in 1943 isn't necessarily going to bring the war to a faster conclusion, it may just destroy France a lot more and drag that front out quite a bit longer and more in order with OTL 1944 planning assumptions of how long it would take to liberate France.
 
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CalBear

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Sledgehammer was an invasion plan drawn up in 1942 by the Allies to invade mainland Europe through france in the spring or summer of 1943.

If that came to fruition what would have been the outcome on the war? I assume a bigger and longer western front emerging.
The result?

The invasion is repulsed. Massive losses.

The WAllies didn't have sufficient lift to move the necessary troops. Didn't have control of the air over France. Hadn't figured out proper amphibious tactics yet. American forces both officers and enlisted ranks, what there were in Europe, were still green.

Total bloodbath. Open question if the Wallies ever try again. In all likelihood the British get their way and the whole Balkan's debacle happens.
 
The WAllies didn't have sufficient lift to move the necessary troops. Didn't have control of the air over France. Hadn't figured out proper amphibious tactics yet. American forces both officers and enlisted ranks, what there were in Europe, were still green.

And yet Husky and Avalanche succeeded, the latter with German Panzer divisions located at the beaches.
 
The material preponderance is a lot smaller so casualty ratios are going to be a lot more even. I think the Allies would end up in Berlin ahead of schedule but there would be several hundred thousand additional WAllied dead.
 

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And yet Husky and Avalanche succeeded, the latter with German Panzer divisions located at the beaches.
They did. Massive differences however.

The Husky amphibious landing force was less than half the size and strength of the force that landed in Normandy (~2,700 vessels vs 6,900). Opposition was primarily two strong German divisions and the Italian 6th Army, which was of very uneven quality, although some elements fought very tenaciously, many others folded. This can be best illustrated by the fact that the U.S. landing force suffered 58 KIA, 199 WIA, and counted 700 MIA at the end of the first day, having created a solid lodgement and taking 4,000 prisoners (TOTAL Heer casualties on D-Day were roughly 1,000), with The Canadian 1st ID taking an additional 500. However the Italian "Napoli" offered fierce resistance.. The Axis forces on Sicily had very little hope of worthwhile reinforcement, again a huge difference that that which existed in France.

Avalanche's landings near Salerno did indeed occur where the 16th Panzer was charged with the defense. 16th Panzer also had to defend the entire Sorrento Peninsula and the shoreline south to Agropoli, and do it alone, since the Italian force originally assigned to provide defense of the region had been withdrawn with Italy's surrender. This left the Division to cover well over 50 miles of frontage with virtually no shore defenses beyond some barbed wire and a belt of Teller mines. This being the case the Divisions CO had spread his armor out in "penny packets" in hopes of disrupting any landings. This vastly diluted the potential combat power of the Division, as can be seen in the combat histories of the 36th Division were number attacks by anywhere between four and fourteen Pz IV are noted, none of these small platoon/company size attacks managed to penetrate defenses thrown up by the assaulting battalions. It is an interesting WI to consider what might have happened had the 16th Panzer managed to maintain it armored forces in battalion size groups rather than the much smaller unit attacks.

It is also critical to note that at both Silicy and Southern Italy the commanders of the landing forces made errors that, had they happened against the far more substantial Heer forces available in France instead of Italian conscripts with sub-standard weapons, training and very uneven leadership or widely spread out Herr forces would have been disastrous.

Enemy air opposition to the two landing was also manageable, although the WAllies did not enjoy the virtually uncontested airspace the existed over Normandy in mid 1944. In 1943 the WAllied air forces would have been hard pressed to manage air parity and any paratroop or glider deployments would have face not just AAA but Luftwaffe Nightfighters. Even if the RAF/8th AF managed to keep Luftwaffe attackers away from the landing forces the effort would mean that the huge amount of CAS that the landing forces enjoyed, and the ongoing interdiction by fighter bombers range over the landing area would have been diverted to the air battle. In Spring-Summer of 1943 the 8th AF was still getting slaughtered over Germany and the lack of fighter escort deep into Germany was preventing the hammer & anvil tactics that, combined with the CBO, over the following year destroyed the Luftwaffe as a fighting force.

Lastly, a specific word about the chances for a 1943 landing. As late as mid 1943 the U.S. & British were still working out the whole "landing craft" idea. in March of 1943 (and this will sound distressingly familiar) the British were actively working on the conversion of barges and coastal steamers for at least the follow up waves of any landing force. The landing craft that were available in their literal thousands, and not even begun to be constructed in sufficient numbers (the first LCT was not even delivered until September of 1942). One thing that is often overlooked when discussing things like landing craft is that the WAllies didn't land that many more troops in the first wave on D-Day than was the case in the Med, but those troops were just the door kickers, in the three weeks after the initial landings the WAllies inserted an additional 710,000 troops, with many more following in the following months. The WAllied didn't HAVE 875,000 troops in the entire ETO in mid 1943. Many of those men were either just finishing recruit training or had not yet even received their orders to report for induction. Even with the extra year to build up forces it was necessary to pull divisions out of Italy to reinforce the French campaign (it wasn't just Mark Clark's command skills that effectively ended the offensive up the Italian Peninsula/

tl;dr: Not the same situation, at all.
 

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And yet Husky and Avalanche succeeded, the latter with German Panzer divisions located at the beaches.
Italy isn't France, especially after Tunisia and later Sicily had gutted the Axis armies.
 
The material preponderance is a lot smaller so casualty ratios are going to be a lot more even.

The material ratios are very different at first, smaller in total for both sides whenever the start is. ie: the Cotienten peninsula was defended by one mobile infantry division & one half strength static division in October 1942, vs three static, 2-3 mobile infantry, and a armored division in June 1944. Neither were there beach defenses in place during most of 1943. The strategy until Rommel assumed command was to fight the Allies inland, with only the ports defended and just a out post or observation post network along the beaches. The numbers, quality, firepower, and general capability of the forces added by each side during 1943 7 the first half of 1944 are very different and don't easily summarize in a few sentences.

I think the Allies would end up in Berlin ahead of schedule but there would be several hundred thousand additional WAllied dead.

This probably translates to a proportionate number not dead on some other front. The Italian campaign cost the Allies app roc half a million maimed and dead. if transferring those losses to NW Europe ends too war six months earlier or three months earlier then is the shift worth it? What about half a million fewer losses in the east. Are are the lives of Poles, Urkrainian, Gerogian, Tartar, Mongol, & odd Korean counted the same as west Allied soldiers? It also may be the differing circumstances and decisions create larger casualties across the board, or it may be the total are reduced substantially. This question has been touched on in other threads with varying estimates. Have not yet run across many historians who have done a in depth analysis of it. If anyone cane point to such I'd appreciate it.

Carl, didn't you post a link a while ago to a study by G. Michael Giumarra comparing D-Day 1942 and D-Day 1944? I've got the PDF but don't have the link. This study is a very good analysis about Sledgehammer and gives a lot of advantages the Allies would have in doing an early invasion of the continent, and several difficulties that could arise.

This was a very interesting read, and would probably help in this discussion if anyone can find the link.

I'm not at my office & desktop. I'll try to remember to post the link to the PDF of Guimarras essay. The short version is Guimarra briefly summed up the 1942 invasion plans of the Brits, & then went into detail on the single most complete of the several plans. This specific plan was written in the summer of 1942, being more or less complete by the end of July, with subsequent work thru September. The target date/s for it fell in October 1942. As such it was a direct alternate to Op GYMNAST & TORCH. Oddly this plan contemplated just a single division in the initial assault, and a build up of one corps in the first few days. By contrast Op TORCH had three divisions in the initial assaults & landed three corps in the initial build up. Another contrast is this 1942 'SLEDGEHAMMER plan was to use primarily British formations, while TORCH included half US formations. Why the GYMNAST and TORCH operations were larger than this other plan I'm unsure.
 
They did. Massive differences however.

And there were massive differences on the German side as well. As previously mentioned the beaches of France and Belgium were under defended for most of 1943. The French had better beach defenses on the Morrocan coast. In mid 1943 the proportion of static divisions, third rate infantry divisions, and spent half rebuilt divisions from the eastern front was much higher.

Enemy air opposition to the two landing was also manageable, although the WAllies did not enjoy the virtually uncontested airspace the existed over Normandy in mid 1944. In 1943 the WAllied air forces would have been hard pressed to manage air parity and any paratroop or glider deployments would have face not just AAA but Luftwaffe Nightfighters. Even if the RAF/8th AF managed to keep Luftwaffe attackers away from the landing forces the effort would mean that the huge amount of CAS that the landing forces enjoyed, and the ongoing interdiction by fighter bombers range over the landing area would have been diverted to the air battle. In Spring-Summer of 1943 the 8th AF was still getting slaughtered over Germany and the lack of fighter escort deep into Germany was preventing the hammer & anvil tactics that, combined with the CBO, over the following year destroyed the Luftwaffe as a fighting force.

To oppose the Allied summer offensives in Italy in 1943 the Axis had rebuilt their air forces in the MTO to 2000+ operational aircraft. 2,400 by one account, 2,800 by another that may be including aircraft in Rumania and other reserves. The Allied operational strength in the MTO is placed between 4,500 & a bit over 6,000 depending again on who and how the counting is made. As far as I can tell the Germans in mid 1943 had approx 300 aircraft in imeandiate range of the Flanders/Normandy region, and perhaps another 500 ranged between Frisia and the Riveria. Then whatever was defending the Reich in June 43, 600?. The balance were on the eastern front. Unfortunatly I don't recall what the Allies had in the UK mid 1943. I would expect with the priority shifted from Italy to NW Europe A hefty portion of the Allied air strength in the MTO would have been built up in the UK instead.
 
The WAllied didn't HAVE 875,000 troops in the entire ETO in mid 1943. Many of those men were either just finishing recruit training or had not yet even received their orders to report for induction. Even with the extra year to build up forces it was necessary to pull divisions out of Italy to reinforce the French campaign (it wasn't just Mark Clark's command skills that effectively ended the offensive up the Italian Peninsula/

Well, yes. On the other hand in early 1942 Marshall's plan was to have 30 Divisions in the UK by April 1943.

There are questions whether this was feasible, but in reality up to the end of March 1943 the US sent double the number of divisions to the Pacific that they sent to Europe; they also had more than 20 divisions in the US that had been in existence for more than a year.
 
The result?

The invasion is repulsed. Massive losses.

The WAllies didn't have sufficient lift to move the necessary troops. Didn't have control of the air over France. Hadn't figured out proper amphibious tactics yet. American forces both officers and enlisted ranks, what there were in Europe, were still green.

Total bloodbath. Open question if the Wallies ever try again. In all likelihood the British get their way and the whole Balkan's debacle happens

Like Carl Schwamberger points out, Sledgehammer isn't Overlord 1942, but a toehold in the Cotentin peninsula. It would have quite an effect on
MTO and Eastern Front as well, as Hitler would most likely go bonkers and try to evict the force with the full might of Heer - thus easening up
the job in MTO and Eastern Front at a critical juncture.

By this time the Allies, but especially the British, were very skilled in defense. On Cotentin there would be a stage for a large planned battle with massive air, naval and artillery support - a form of battle where the British excelled. Particularly if they have Montgomery for a commander. Best case would be a methodical battle with advance in small stages where the Allied material superiority would be at it's best, possibilities for German tactical brilliance at smallest and the US Army would get it's combat laurels.

If the Allies lose, it's bad, but that's war, that happens. If - like in all probability they will - hold, then they have tied up a massive amount of German forces and have fighter bases on the continent. Meanwhile, the Med is open for a follow up. Sicily, Sardinia and Corsica, followed up by invasion of Southern France in Autumn 1943 would be a tempting option, probably with a maskirovka operation about landings in Northern Italy or Normandy or Calais region. After an invasion of Southern France it's time to release the US and Commonwealth mechanized might from Cotentin.

What about Germany? They will have the option of either making a large offensive in the East a la Kursk, or trying to evict the Allies from Cotentin. Either way, they would be supplying an army in Africa (if not evicted by then) and / or guarding the Mediterranean against an Allied invasion.

The best case would be that they would try to evict the Allies from Cotentin as they would run into a meatgrinder. Royal Artillery, alongside RAF Fighter Command, 2 TAF and Royal Navy would be all smiling, with their US Allies entering the battle with an increasing force.

But let's explore the possibility of a Sledgehammer fail. This would still mean Germany would have to commit massive forces in France, away from MTO and the Eastern Front, thus helping the Allied main cause. This would also mean straightening up the Western Allied act even faster than North Africa, Sicily and Italy. In the end, tactical German victory, strategic loss.
 
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... But let's explore the possibility of a Sledgehammer fail. This would still mean Germany would have to commit massive forces in France, away from MTO and the Eastern Front, thus helping the Allied main cause. This would also mean straightening up the Western Allied act even faster than North Africa, Sicily and Italy. In the end, tactical German victory, strategic loss.

A 1942 or 43 fail in NWE might also mean Hitler thinks he has won the war leaves the Atlantic front undefended. Ten months later, or whatever, the Allies return with multiple army groups, lessons learned, and a bigger AF. Hitler was mercurial, and was vulnerable to deception ops. Odds are he'd have the marshals reduce some strength in the west, or at least not increase it substantially. After all if 35 mostly second rate divisions could defeat the Allies in the winter of 1942-43 why overreact six or ten months later?
 
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