Sledgehammer in '42?
I think we have to look at the effect on Torch, El Alamein, & Guadalcanal. Pulling off Sledgehammer is gonna take everything we've got, so let's see what that is.
1st of all, Torch has gotta be cancelled. You can do Sledgehammer or you can do Torch-- you can't do both.
2d, instead of sending the 1st Marine Div. to Guadalcanal we'll have to use it in Sledgehammer. 2d Marine Div. is spread out garrisoning American Samoa, California, & Iceland, so we can gather it together & use it too. A bde. in American Samoa is no more gonna be able to defend Samoa than the troops on Wake & Guam were, & by 1942 the threat to Iceland is pretty much over. Replace the 6th Marine Rgt. up there with a Nat'l. Gd. unit.
...and 3d, reinforcements slated for Monty in Egypt will have to be diverted to support Sledgehammer. There's just no way around this, because U.S. forces won't be able to carry the ball themselves.
It does us absolutely no good to invade Europe unless we can at least defend what we take, & that's gonna require literally everything we've got.
The 1st Armd. Div. arrived in England in May of '42, but contrary to popular belief the entire 2d Armd. Div. didn't go into combat until Sicily in the summer of '43. Only certain elements of the 2d Armd. Div. took part in Torch, so maybe a rgt. or two will be available for Sledgehammer-- we'll say the 66th Armd. &/or the 41st Armd. Inf. The 1st Armd. Div. will provide support.
In addition the 509th PIR arrived in England in early '42, the 1st ID arrived in Aug., & we've got the 2 Marine divs. That's it. All other U.S. combat formations are still in training. If we slip the invasion date into late Sept. then we might get 1 more U.S. inf. div., but with the other Allies we aren't that short of inf.
To these forces we can add maybe the Brit. 6th Armd Div., the Canadian 1st Armd. Div. (equipped with stuff diverted from the Murmansk convoys), from 4 to 6 Anglo-Canadian inf. divs., a div. of Poles, maybe a div. or so of Free French, & roughly a mixed div. of Belgians & Dutch.
3 armd. & a maximum of around 3 U.S., 4 to 6 Anglo-Canadian, & 3 other Allied inf. divs. 13 to 15 divs. total-- & that's scraping the barrel. Against ~25 Wehrmacht divs. with substantial Luftwaffe support, I see a stalemate as the best possible result. You'll probably get a stalemate in the air, & you've got a slight edge in armor (3 armd. divs. vs 2), so you might be able to defend 1 or 2 ports along the Channel-- for a little while-- but you've got nothing to penetrate & exploit with. You'll be hanging on with your fingernails, & with no reserves whatsoever.
To achieve this you've diverted Monty's reinforcements, so El Alamein becomes a stalemate at best. At worst you've lost Egypt & opened up the Middle East to invasion, with their pro-German populations. You've written off Torch, so Rommel has no one in his rear threatening to cut off his supply. If he crosses the Suez then you could face a disaster in the Middle East, with pro-German Arabs rising up against small Brit garrisons.
You've also had to give the Japs a free hand in the SW. Pacific. They've already lost the battle of Midway, so their long-range strategic power projection is compromised, forcing them to focus on short-range gains. Their air base on Guadalcanal now threatens Allied supply into Australia. The Kokoda Track Campaign took place between July & Nov. 1942, & if it goes differently because the Japs now don't have to divert troops & supplies to Guadalcanal, then Port Moresby is lost. A Jap airbase at Port Moresby brings all of NE. Australia within bombing range & protects both Rabaul & the Solomons. Australia is too huge to be conquered, much less occupied, but this would largely neutralize it.
I see Hitler cancelling his drive on Stalingrad in order to shorten his lines. It's also possible that instead of continuing to tie down troops trying to starve Leningrad into surrender, he'll order an assault which will most likely succeed. In Leningrad by this time they didn't have much left to fight with. He'll do these things in order to conserve forces to wipe out the Allied lodgements in France, which will be planned for the winter of '42-43.
Whether he succeeds or not-- & he probably will-- this works to Hitler's strong advantage. He'll eliminate the bleeding ulcer of Leningrad, tying down nearly a quarter of his army; & he won't lose over half a million men in Stalingrad that winter.
By transferring troops Hitler will almost certainly be able to eliminate the Allied bridgeheads-- so yeah, you get Dunkirk v.2; but the big question is, can Russia use this diversion to turn the tables against Germany? I think there'll be some limited gains made, but I don't see a big strategic reversal here on the Eastern Front.
Here's why :
Sledgehammer in '42 achieves something that the German generals tried to do for the entire war & never succeeded in. It gets Hitler into a defensive deployment on the Eastern Front. By deploying defensively & forcing the Russians to come to them, I think the Wehrmacht does even better than in OTL, & maybe Hitler will learn a valuable lesson that'll enable him to prolong the war for 2 or 3 more years.
So overall, I think that Sledgehammer in '42 works to the German advantage on almost every level.
--Thegn.
