Since no one else has commented on this yet, I just wanted to pipe up and say I was amazed at this suggestion.
The Seven-Years war was certainly fought on various continents, but I don't think it involved the kind of military technology characteristic of what we consider a "world war." It's more than just location.
If you wrote a TL on this, I would totally read it. It's certainly an interesting clusterfuck of a war, though I suspect the US and the Anglo French would make peace at the first opportunity, now that the US has succeeded in screwing up the CSA's chances.
Thank you.
Writing chronological timelines is a skill I haven't yet mastered. Most of what I have on the board is what I could write out in a sitting, unfortunately, like the above. Larger things I write like I'm editing a wiki - the end result may be good, but it's not terribly exciting to read the updates!
It is an interesting scenario though, isn't it?
To my mind it comes down to three things: weighing Britain down, getting America in, and keeping Russia in.
Britain's dominance effectively prevented total wars from becoming general wars. If the fight involves Britain you can't win and the longer you go on, the more likely it is that a third party joins in on London's side. If the fight doesn't involve Britain, you have to end it quick or risk British intervention. Pax Britannica is actually a fairly valid descriptor for the period. I'd argue the thing that ultimately protected America (though note, not its neighbors) was public sentiment in Britain created by a war officially about slavery.