The Empire of Time — David Wingrove

There is only the war.

Otto Behr is a German agent, fighting his Russian counterparts across three millennia, manipulating history for moments in time that can change everything.

Only the remnants of two great nations stand and for Otto, the war is life itself, the last hope for his people.

But in a world where realities shift and memory is never constant, nothing is certain, least of all the chance of a future with his Russian love...