As I was playing today, I had one of my horseman just flat out DIE in the jungle as I was marching from one city to the next.
I've never had this happen before...anyone know the odds? Is it just jungle or possible in tundra, desert, etc?

It wasn't actually the horseman Elear. It was the horse. Your troop then went turncoat as you gave hime a bad horse.![]()
Ouch.I can verify that units do not die as long as you do not fort them. I once had an army die that way and now I will not fortify anything in a jungle.
I wouldn't mind if they lost an HP or two every once in awhile, that is reallistic -- but a whole unit just disappearing? Especially a modern one, or an army?? No!!
But it's only jungle where units die, not floodplains.
How about marsh?
Pretty sure that can happen, but not guaranteed.
Marsh can definitely cause disease in your cities. I am pretty sure it can kill troops, as well.
I'd test that if my computer's disk drive wasn't currently being screwy