Pale guardian : a James Asher vampire novel
(Book)

"The vampires call them 'The Others'. Neither living nor dead, the revenants are mindless and unstoppable - and in the carnage of the First World War, governments already running short of men to throw into battle might be very interested in soldiers who don't ask questions and are hard to kill. Front-line volunteer nurse Lydia Asher is horrified to learn that someone has found a way to control revenants, and is creating them for this purpose. Back in London, Lydia's husband, former spy James Asher, is even more appalled to learn that revenants are beginning to show up in England, on the loose. Since revenants devour vampires, the vampires of Europe - most of whom are at the Front, feeding completely unnoticed on the dying - join forces with the Ashers to find the source of the threat before the world is overwhelmed"--Book jacket.