My theory
Everybody says they think the Great War is WW1 or 2, but I have a different theory. If it was WW1 or 2 then there'd be survivors other than Salad. I think this is far murther into the future, and that the toilet (see episode 6) has something to do with why he still thinks it's going on. Great series, by the way. Freaky, but in a good way