American Sealion

What is the earliest point in which the United States can sucessfully invade Britain? This is in the context of ATLs where the USA fights the UK in a major war during the 20th Century.
 
With little or no variation from OTL forces and equipment? I'd say late 1944/early 1945 at the earliest. The long-range amphibious ships needed to cross the Atlantic and land troops on a hostile beach just don't exist in sufficient numbers until then, nor do the carriers to provide air cover.

Even then, such an invasion would make the invasion of Japan look easy. Logistics and protecting the supply lines would be an absolute nightmare, even assuming the Royal Navy is long gone.
 
With little or no variation from OTL forces and equipment? I'd say late 1944/early 1945 at the earliest. The long-range amphibious ships needed to cross the Atlantic and land troops on a hostile beach just don't exist in sufficient numbers until then, nor do the carriers to provide air cover.

Even then, such an invasion would make the invasion of Japan look easy. Logistics and protecting the supply lines would be an absolute nightmare, even assuming the Royal Navy is long gone.

What if it were from Ireland, and then launch the major operation from there?
 
What if it were from Ireland, and then launch the major operation from there?

Assuming Ireland is defended, same problem. You still need to assault-load equipment and troops in, say, New York, and sail all the way across the Atlantic. You can't do that with LCI's (they could cross the Atlantic on their own, but not with a troop load). Nor are your amphibs going to be making the loop fast with reinforcements; heck, with LST's (a their jackrabbit speeds of 10.8kts) it would take over three weeks to make a single round trip, allowing no time for loading and replenishing (or zig-zagging, or that no convoy of will sustain full speed, or...).

Also, no paratroops, no land-based air support, not even an anchorage for battle-damage repairs to the fleet, or for cross-loading ammo and fuel from tankers and merchant ships to fleet auxiliaries.

I'm actually going to say 1945 at the earliest, assuming near-same development of ships, techniques, etc.
 

CalBear

Moderator
Donor
Monthly Donor
Late 1945-46

This would be Downfall, except even more complex. I'm not at all sure it is even possible without serious use of Special Weapons.
 
One possibility might be to take and stage out of the Orkney/Shetland islands.
Problem is the weather up there is terrible for most of the year. But they would make it a bit easier.
Would still be a nightmare, as the RN has subs, working torpedoes, and some rather good sub skippers, even if you can totally suppress the air defences.
 
Britain would likely invade Ireland, but if the Americans landed on Ireland (who would without a doubt be putting up one hell of a fight) and helped in the liberation, they would have a perfect launching point to invade britain. i imagine there would be quite the resistance force in Ireland, like the French resistance but with more car-bombs. The US, then would probably go for either Liverpool (lots of Irish in Liverpool means perhaps pro-Irish sentiment?) or somewhere in Wales.

I guess a POD would be if the UK decides to side with Hitler during WW2, or maybe even they don't join the entente, but decide to join the Axis because of their close monarchical relations. Either way, a German ally to UK would cause huge problems for American air superiority
 
Britain would likely invade Ireland, but if the Americans landed on Ireland (who would without a doubt be putting up one hell of a fight) and helped in the liberation, they would have a perfect launching point to invade britain. i imagine there would be quite the resistance force in Ireland, like the French resistance but with more car-bombs. The US, then would probably go for either Liverpool (lots of Irish in Liverpool means perhaps pro-Irish sentiment?) or somewhere in Wales.

I guess a POD would be if the UK decides to side with Hitler during WW2, or maybe even they don't join the entente, but decide to join the Axis because of their close monarchical relations. Either way, a German ally to UK would cause huge problems for American air superiority

I'll counter the UK/Germany alliance with an American/Japanese alliance. Come on, let's break one of AH.com's most sacred commandments. :)
 
Late 1945-46

This would be Downfall, except even more complex. I'm not at all sure it is even possible without serious use of Special Weapons.

Probably right. But England is not Japan. Would the English consider resorting to the tactics (mass kamakazis, use of civilians, etc) that the Japanese planned for Downfall? Also, the USA is not Nazi Germany. When push came to shove, would the British people as a whole "fight to the death" when defeat would mean a soft and probably temporary occupation by a fellow English-Speaking democracy?

But wow, imagine how cool a massive sea battle between the US and British navies in the Atlantic as a prelude to the invasion would be. Imagine Jutland meets Leyte Gulf with both sides oozing the best naval technology 1945-46 has to offer. Or even better, massed US air attack from the US base in occupied Iceland results in the detonation of several secret US "special weapons" in and around the British fleet and in utter shock, Britain gives up right then and there!

Would make a neat book.
 
I guess a POD would be if the UK decides to side with Hitler during WW2, or maybe even they don't join the entente, but decide to join the Axis because of their close monarchical relations. Either way, a German ally to UK would cause huge problems for American air superiority

Grrrrrrrrrrr. :mad:

Whereas the former is so splendidly unlikely as to be humourous, the latter is altogether impossible - and would besides that mean that Ireland was already part of the UK, pretty much invalidating the first bit of your post, which also had its share of misconception (no disrespect intended, but the Irish army couldn't do tuppence and they knew it; why Wales?).

PBut England is not Japan. Would the English consider resorting to the tactics (mass kamakazis, use of civilians, etc) that the Japanese planned for Downfall?

The real question is whether Wales would resort to such methods. :p

(England is not Britain.)
 
But wow, imagine how cool a massive sea battle between the US and British navies in the Atlantic as a prelude to the invasion would be. Imagine Jutland meets Leyte Gulf with both sides oozing the best naval technology 1945-46 has to offer. Or even better, massed US air attack from the US base in occupied Iceland results in the detonation of several secret US "special weapons" in and around the British fleet and in utter shock, Britain gives up right then and there!

Would make a neat book.

Umm... with all due respect to the Royal Navy, it would be a trifle one-sided. The biggest RN fleet carriers had air groups half the size of their USN counterparts, and there were fewer decks to begin with. Seven modern battleships against ten, etc., etc.

Not that the USN wouldn't take losses, but the simple fact is that in 1945 the USN was more powerful than every other navy in the world combined.
 
The US, then would probably go for either Liverpool (lots of Irish in Liverpool means perhaps pro-Irish sentiment?) or somewhere in Wales.

To successfully stage a Sealion, the US would need to get their hands on a really big port opposite of Ireland. "Somewhere in Wale", as beautiful as the scenery is, won't be of much help.

Liverpool is the scenario. I imagine the invasion to happen on the beaches of Blackpool and Southport and the US forces would go South and Southeast from there towards Manchester and especially Liverpool.

The only alternative objectives are not inviting at all, as they are rather deep inlands, sending every shipment through long sounds where enemy outposts might cause trouble for time to come (see Antwerp). This cancels
out Glasgow as well as the Swansea/Cardiff/Bristol-region.

---

However, I am not sure if the UK wouldn't be able to prove tougher than Japan could have been. More industry, a bigger navy, probably a more modern Air Force. I have serious doubt if the US are able to get their hands on Ireland if not in a Pearl-Harbor-like surprise scenario with Dublin's friendly invitation.
But, I deem it a 99% certainty, that in the way up to such a conflict, something must have happened concerning Canada, which would warn Britain just as the occupation of Prague had been a wake-up call.
Forces in Ulster would be prepared to move in this timeline.

---

However, though Ireland looks like the direct route, someone with more knowledge about the place should tell us about the possibilties. Does it possess the ports to make it the staging ground for destroying the British Empire? I would also point out that Dublin and Belfast are in a vulnerable position opposite Britain.

---

The more I think of it, the more it ressembles an ordinary sea mammal of the unspeakable kind, unless, as others pointed out, the US find Allies on the mainland - either France or a Germany which controls enough coastline to allow a strategical connection with America via Norway or Northwestern France; or both countries united.

---

Far cheaper idea: just undermine the Brits as in "The Ghostwriter". ;)
 
Umm... with all due respect to the Royal Navy, it would be a trifle one-sided. The biggest RN fleet carriers had air groups half the size of their USN counterparts, and there were fewer decks to begin with. Seven modern battleships against ten, etc., etc.

Not that the USN wouldn't take losses, but the simple fact is that in 1945 the USN was more powerful than every other navy in the world combined.

It still would be the most equal massed fleet engagement since Jutland. Also, I don't think you can reasonably stick the historical 1945-46 US and British fleets into this discussion since we are obviosuly talking about a situation in which "our" WW2 did not occur. Unless one wanted to presume a truly wierd PoD, it is reasonable to presume that the US and Britain would both have large and modern fleets in a 1945 in which this situation is possible. Beyond that, the exact makeup of the fleets is subject to conjecture. Absent the Pacific War with Japan, it is highly doubtful that the USA would have developed the large fleet carriers they ended WW2 with, nor not nearly as many carriers. Battleships might still be the core of both fleets. I think a rough extrapolation of the fleet sizes and makeup each nation had in 1939-40 would be a better gauge of equivalent strength for such a speculation than what they posessed in "our" 1945
 
However, I am not sure if the UK wouldn't be able to prove tougher than Japan could have been. More industry, a bigger navy, probably a more modern Air Force. I have serious doubt if the US are able to get their hands on Ireland if not in a Pearl-Harbor-like surprise scenario with Dublin's friendly invitation.

Tougher, certainly, but look at how utterly the US crushed Japan. I'm sure the UK could have held off the US in 1941, and for all I know in 1950, but 1945 was in some ways the peak of the US armed forces and their ability to project power across huge distances. The USN can easily bring 20 fleet carriers each with roughly a hundred aircraft to the party, plus 80 light and escort carriers. All that is including OTL losses, and a margin for ships unavailable for whatever reason. Even the RAF is going to have trouble. The Fleet Air Arm will die, probably gloriously, but they will die.

But, I deem it a 99% certainty, that in the way up to such a conflict, something must have happened concerning Canada, which would warn Britain just as the occupation of Prague had been a wake-up call.
Forces in Ulster would be prepared to move in this timeline.

True. However what can the UK do about it? The US can isolate the UK from the rest of the empire (though not from the continent). Remember that the US submarine forces succeeded in doing to Japan what the Germans tried to do to the UK. They can do the same thing again.

Of course, all of this assumes the US and the UK winding up on opposite sides while their military forces progress at OTL rates, which is... unlikely.
 
It still would be the most equal massed fleet engagement since Jutland.

Um... Midway? And it wouldn't be that equal. The RN would be heavily outnumbered and would have a hard time inflicting heavy losses on the USN.

Also, I don't think you can reasonably stick the historical 1945-46 US and British fleets into this discussion since we are obviosuly talking about a situation in which "our" WW2 did not occur.

Very true. However, anything else is random speculation without a PoD, which the OP did not provide.

I will happily concede that in OTL 1941, or with any similar force levels, the UK could hold the Isles against the US without any difficulty.
 
What if it were from Ireland, and then launch the major operation from there?

Ahem, Ireland would make the Pacific war look like a picnic!
Well not really, but still, you've got a population who've been fighting either the Brits or each other in some nasty guerilla combat since the 20's.
The Brits knew what they'd be up against if they invaded Ireland, hence Plan W was to be a cooperative procedure rather then just a British invasion which would have increased pro-Axis sentiment (and there was enough of it already) and lead to the creation of another front that would be a ridiculous drain on resources!

Anyway, why can't the USA just get Ireland into an alliance?
 
Top