So I've been thinking: [b]Expeditionary Forces[/b]
There would be lots of forces far from home, be it colonial troops, expeditionary divisions or paratroopers. I'm thinking of a faction that serves as a small group of descendants from the very angry and isolated remnants of these soldiers. They'd be primarily concentrated around different parts of the Siegfried line and generally be a nuisance for everyone involved, attacking anyone they can for supplies and even raiding towns that survived for food. 

Primarily it's American and British Empire troops/equipment, though it is a hodgepodge of just about anyone who was stranded post-war.

Though I don't imagine these guys are the majority of troops [i](especially if your from the British Isles, since, y'know, you can just walk to Northern France and take a boat)[/i] but more so extremist offshoots who stuck around blinded by their rage and wanted to raid some people and blow things up. It isn't like they have hundreds upon hundreds of tanks at their disposal or act as a actual nation- think more so bandits, very organized and pissed off bandits who all scream in various accents and some different languages, through primarily English.

[hider=Visual Ideas for Equipment]
The top sketch is USA, the second one British Empire. Took some liberties with the setting adding in balaclavas, rebreathers and ski-goggles.

[img]https://i.imgur.com/AWaoW5B.jpg?1[/img]

[img]https://i.imgur.com/aEBUVJv.jpg?1[/img]
[/hider]