How would a war between America and Britain during the interwar period have played out?

[Ambusher11]

Yes, I'm well aware that this particular scenario has been trotted out quite a bit on the forum, with people usually stating that such a war would be highly unlikely to occur and that War Plan Red was just a routine exercise like the modern day zombie defense exercises. I'm not going to dispute this argument right now, I'm just interested in how a war between America and Britain during the interwar period would've played out.

Speaking of War Plan Red, I recently found the actual War Plan Red document online, which you can read here. Basically, in a nutshell, this plan called for:

1. Initial offensive operations in Canada attempting to capture Halifax, the Montreal-Quebec area, the canals and rivers connecting the Great Lakes, Winnipeg, and Vancouver, and ultimately to capture all of Canada.
2. Naval operations initially attempting to reinforce the defenses of the Panama Canal, Hawaii, Puerto Rico, seize Jamaica, Bermuda, the Bahamas, gain control of the Western North Atlantic and the Eastern Pacific and blockade Canada, and ultimately to capture Trinidad, St. Lucia, and all other British Caribbean and Central American possessions.
3. Ultimately, to attempt to force Britain to sue for peace by destroying her economy.

If a war between the U.S. and the British Empire were to break out during the interwar period, what would the outcome of the war be?

 

[West234]

Britain would dominate the sea but America can just take Canada and the Caribbean colonies and sit back they would only really risk loosing the philippines and some pacific islands. Britain might try and reinforce Canada before hand but realistically they would never be able to hold it given how seriously outnumbered they are. Canada did have there own defense plan to invade the USA itself to give Britain time to reinforce Canada with more troops but realistically they would’ve been able to pull this off and America would rapidly take all the major Canadian cities.

 

[CarlosMalvinas]

I think world tension would go up to like 89% and if it was a multiplayer game whoever is playing Germsny or Russia would have a pretty good tjme

 

[GuildedAgeNostalgia]

1) Pacific Theatre

Britain persuades Japan to join the war by promising them Hawaii, Philippines, Guam, the Aleutians, and Wake. Australia gets Samoa and the Marshall Islands, and those other uninhabited atolls the US has in the South Pacific.

British-Japanese-Commonwealth alliance destroys the US Pacific fleet and terrorizes the West Coast of the US.

2) Caribbean Theatre

British lose Belize because the US Allies with Guatemala and Mexico allows the Americans to move troops overland into Guatemala. Naval war in this theater starts out as a stalemate but over time the US attritions the United Kingdom. British islands fall one by one until they are all occupied. By this time however, the Panama Canal is destroyed beyond repair, securing British superiority in the Pacific, Suriname aluminum facilities are cut off from the American economy. British see the Caribbean as a lost cause and devote all of their Atlantic naval assets to Canada.

3) Canadian Theatre:

Everything south of the St. Lawrence falls relatively quickly but the British funnel in enough men to hold off an American river crossing. Greenland's cryolite mines are cut off from the US. This combined with losing temporary access to South America's aluminum mines, the US aircraft industry is severely hampered, allowing the British to have complete air superiority over Eastern Canada. The Coast of British Columbia is also safe from American offensives due to British naval superiority in the Pacific and the US loses Alaska. Central Canada however will fall to the US and Canada is split in 2. The US has the manpower to force a victory, but it comes at a very heavy cost.




I do think Japan joining the war is what makes this scenario pretty interesting.

 

[GuildedAgeNostalgia]

Britain would dominate the sea but America can just take Canada and the Caribbean colonies and sit back they would only really risk loosing the philippines and some pacific islands. Britain might try and reinforce Canada before hand but realistically they would never be able to hold it given how seriously outnumbered they are. Canada did have there own defense plan to invade the USA itself to give Britain time to reinforce Canada with more troops but realistically they would’ve been able to pull this off and America would rapidly take all the major Canadian cities.

US would not be prepared for a war. The terrain of Canada is not ideal for armored offensives. Infrastructure would be destroyed and initial American offensives would grind to a halt. Eventually the US wins in Canada as it's economy slowly mobilizes, but it wouldn't be quick.

 

[GuildedAgeNostalgia]

American tanks in the late 20s, early 30s were outdated WW1 models.

 

[nbcman]

US would not be prepared for a war. The terrain of Canada is not ideal for armored offensives. Infrastructure would be destroyed and initial American offensives would grind to a halt. Eventually the US wins in Canada as it's economy slowly mobilizes, but it wouldn't be quick.

American tanks in the late 20s, early 30s were outdated WW1 models.

If there was sufficient tension for there to be a US - Commonwealth war in the 1920s or 1930s, why would the US (or for that matter the Commonwealth & the rest of the world) be as unprepared as OTL?

 

[GuildedAgeNostalgia]

If there was sufficient tension for there to be a US - Commonwealth war in the 1920s or 1930s, why would the US (or for that matter the Commonwealth & the rest of the world) be as unprepared as OTL?

You can still be unprepared while you are preparing.

The US was arguably unprepared for WW2 when they joined in otl, based off early experiences in N. Africa and the Pacific.

Underpepared is probably a better adjective to use

 

[Emperor Norton I]

Britain would dominate the sea but America can just take Canada and the Caribbean colonies and sit back they would only really risk loosing the philippines and some pacific islands. Britain might try and reinforce Canada before hand but realistically they would never be able to hold it given how seriously outnumbered they are. Canada did have there own defense plan to invade the USA itself to give Britain time to reinforce Canada with more troops but realistically they would’ve been able to pull this off and America would rapidly take all the major Canadian cities.

My immediate thought goes to overseas trade and shipping in this scenario. The US was isolationist but not economically isolationist.

 

[DougM]

You need to be a bit more spicific. When exactly would this happen? How much lead do we get? If the US has three to 5 years warning to build up its Navy and start other arms build ups then GB is toast. The US could have built up similar to what it did for WW2 and that is just more than GB can deal with. Add in that the US is more or less getting home court advantage and on the ground only has to deal with Canada and whatever GB can get yo Canada and it is going to be US walking over Canada and otherwise defeating GB. With no dispute leading to a build up then it will be worse for the US, but the longer it goes the more it swings in US’s favor. You. Simply can’t get past that be 1940 the US is able to out build anyone.

 

[Garrison]

Britain would dominate the sea but America can just take Canada and the Caribbean colonies and sit back they would only really risk loosing the philippines and some pacific islands. Britain might try and reinforce Canada before hand but realistically they would never be able to hold it given how seriously outnumbered they are. Canada did have there own defense plan to invade the USA itself to give Britain time to reinforce Canada with more troops but realistically they would’ve been able to pull this off and America would rapidly take all the major Canadian cities.

But in the 1930s the US army is almost non-existent and it will take the USA considerable time to gear up for any offensive operations. This of course assumes there is any plausible scenario for the two going to war in the 1930s and given how far the British were willing to go to avoid another costly war I'm having a hard time imagining any point of conflict that would lead to anything more than a diplomatic row.

 

[Ambusher11]

You need to be a bit more spicific. When exactly would this happen? How much lead do we get?

I'm assuming that the war happens in the late 1920s or early 1930s. As for lead time, War Plan Red assumed that there'd be no buildup of forces from OTL levels on either side prior to the beginning of mobilization and war (aside from most of the U.S. Navy being in the Atlantic prior to war).

 

[Arkenfolm]

British naval superiority will rapidly vanish by the third year of the war once US shipyards start churning out endless warships, including large capital ships. Probably by the second year of the war there's enough submarines, surface ships, and hard-gained experience that British shipping to Canada and the Caribbean is seriously contested and naval invasions of anything much west of Hawaii (or Alaska for that matter) rendered impossible.

Canada won't even last past year two since year one will capture or otherwise bring the US right to practically every major city. Once the Great Lakes unfreeze in the spring (and keep in mind that unlike the War of 1812, Britain has no chance to hold the Great Lakes since US shipbuilding far outstrips Canadian shipbuilding), then shipping will be easy, logistics improve, and Canada falls.

 

[DougM]

Frankly Ithink the US can pull together it’s Navy faster to defend the Atlantic then GB can to project its forces into the western Atlantic so I question the assumption that the RN will dominate the Atlantic. Don’t forget that GB is much much more dependent on sea trade then the US is, if for nothing else then because food and almost ALL materials have yo be shipped in. The Uzs can feed itself and otherwise pretty much survive with no shipping it just needs it for some raw materials. (It did ship a lot but it can survive a lit easier without these shipments then GB can)
So I do question the idea that GB will dominate. Its Navy has a lot of responsibilities that it can’t completely abandon. And the US navy is not that small,

 

[DougM]

Ok so why isn’t this in ASB? The proposed war is impossible…. It is one thing to have a war plan that says no warning and no build up but reality is different. Tensions don’t just happen overnight with two counties that were Allie’s and trading partners and culturly and politically realky close just waking up one morning and with ZERO warning go to war. You see a downturn in relations and SOMETHING happens. It will takes months and months of deterioration to get close to a war. Probably years. And if the US is seeing less friendly relations then the various naval agreements are butterflied away. The ONLY reason the US agreed end to any navel agreement was that it was 95% sure that it would have GB on its side in a MAJOR war and 99.999999999999999999999999999999999999999999999999999999999999% sure it would not have to fight GB in a war. Yes it planed for it, that is what the military does it says ”but what if Canada goes insane and tries to invade Detroit?” But just because it thinks about this does not mean it builds defenses on the Ambassador Bridge or mines the tunnels to Windsor.
So the assumption that the US built its defenses on was that GB was not an issue. And to get a war going will see some changes in this relationship with enough notice to change navel treaties or deployments or what gets scrapped or mothballed or SOMETHING. You don’t go from what was probably the best political relationship on the planet yo war with No warning. That is ASB.

Oh and if GB did just suddenly go crazy and attack the US you have two vety likly scenarios in Canada. 1). Canada just notes the hell out of the war and declaims independence and and nutrality at the same time or 2) Quebec declares independence and you get to add that mess in. Heck it is probably more likely that Canada sides with the US then GB if this war just springs up out of noware. As Canada is going yo be PO’d that GB just goes to war for no known reason without consulting Canada about it first.

There is a reason that the longest undefended boarder in the world is the US/Canada border. The relationship between the two countries can no be underestimated. In many respects Canadas economy is so tied to the US that it can’t survive without the US. I used to know of one part that crossed the board over a half dozen times back and forth before it was put into a car and shipped out. It started as a chunk of US made steel going into Canada where started the manufacturing processes and then was shipped between factories as each did something with it until the part was finished then most of the parts were shipped back to a assembly plant in the US to be installed in a car. But some stayed in Canada yo yo into other cars. Some of which stayed in Canada but most of which were shipped to the US.
Then you have cities like Windsor. It is Basically “South Detroit “. I was in Windsor so many times as a young kid that I could not count them if I wanted to. I am nit sure I even realized it was in a sep country until I was older.

 

[MKD]

Britain would win obvs. We could retake our lost colonies and teach those traitors a lesson they wont forget!

I call on all American loyalists to answer the call of his Majesty and stand up to the oppression and tyranny of the republicans. The red coats ARE coming to your aid!

 

[GuildedAgeNostalgia]

Once again, American airplane production will be severely hampered without Greenland's cryolite and South America's aluminum, giving the British obvious air superiority.

Canada's terrain is not great for WW2 style offensives and any progress will be slow for the attacker.

Finally we need to assume that the British aren't stupid enough to get into a 1v1 with the Americans and will activate their alliance with Japan, which drastically changed the Pacific Theatre.

 

[marathag]

US would not be prepared for a war. The terrain of Canada is not ideal for armored offensives. Infrastructure would be destroyed and initial American offensives would grind to a halt. Eventually the US wins in Canada as it's economy slowly mobilizes, but it wouldn't be quick.

Nobody was prepared for War in the 1920s

 

[marathag]

Canada's terrain is not great for WW2 style offensives and any progress will be slow for the attacker.

The important bits of Canada are mostly within 150 miles of the US Border.
US doesn't need to blitzkrieg thru the NW Territories to settle the Canadian Question.

 

[GuildedAgeNostalgia]

The important bits of Canada are mostly within 150 miles of the US Border.
US doesn't need to blitzkrieg thru the NW Territories to settle the Canadian Question.

The St. Lawrence River is a mile wide