Another War — Simon Morden

It starts with a mystery: an old manor house is surrounded by an impenetrable bubble, and all that lives within it seems to wither and die. Investigating, the Army find two men inside the house: men who vanished some 100 years ago but who have now reappeared, and as young as the day they disappeared. There are rumours of a machine which could puncture the dimensions, allowing man to travel beyond the bounds of the Earth ... and for other things to travel here. Another day, another war.