We talk about the US fall into Fascism and the Interwar period after WW1 but now we didn't talked about what happened to other countries afterwards?
What happened to Canada, what happened to Europe, what happened to the CSA after the war?
We don't know exactly what the Confederate war aims were in the Great War, but I imagine their gains were pretty slight. The US isn't going to cede territory or pay reparations to them, so probably the best the Confederates can hope for is Haiti (which they occupied during the war) and maybe the US agreeing not to interfere with any Confederate canal project in Nicaraqua. This will likely lead to a sense of "mutilated victory" in the Confederate States and that sense of dissatisfaction with the war results along with the inevitable high inflation the Confederates will be suffering even in victory will probably still lead to the rise of extremist movements in the Confederate States.
The Confederates will also likely wage a very brutal (and possibly outright genocidal) war to secure their conquest of Haiti. I would expect the Confederate government to also use Haiti as a dumping ground for its more radicalized soldiers (on the theory that it is better to have them in the Caribbean than marching on Richmond) which will make the Haitian War even nastier. (There's a good chance Jake Featherston ends up as one of the Confederate soldiers sent off to fight in Haiti.)
In Europe I expect the British and Russians to quickly fall out. British foreign policy at this time is to keep the strongest continental power in check and with Germany defeated the strongest continental power is now Russia. The Tsar will certainly be feeling his oats after winning the Great War and will probably start pressuring the Turks, Persians, and Japanese for concessions to Russia (which will make the British even more worried about the Russians.) I would expect the British to grow closer to Japan and the Ottomans (to keep Russia in check) and the British might also try to cozy up to Italy (who will doubtlessly be in conflict with Russia's ally Serbia over their dueling interests in the Balkans.)
Nor sure who France sides with in this Anglo-Russian Cold War. The French have much more in common with the British (both being democracies), but France's biggest worry is possible German revanchism and Russia (who is occupying East Prussia) has more of an interest in holding down Germany than Britain (who probably would like to attempt a rapprochement with Germany as another check on Russia.) France will also likely be nervous about Britain making friendly moves towards Italy (who does have claims on some French territory.)
As for Canada that depends on what happens to the United States. If the Socialists come to dominate US politics and take the US in a pacifistic direction then tensions on the US-Canadian border will drop dramatically. Debs or a successor Socialist president will negotiate a treaty with the Canadians that demilitarizes the Great Lakes and Canada will soon be able to end conscription and greatly reduce its military spending.
Conversely, if a fascist government comes to power in the US then Canada is in a lot of trouble. It will have to remain hyper-militarized as it knows it will be a target for the Actionist US in any future war.