Nowhere escaped this common enemy: in Britain, 250,000 people died, in the United States it was 750,000, five times its total military fatalities in the war, while European deaths reached over two million. The numbers are staggering. And yet at the time, news of the danger was suppressed for fear of impacting war-time morale. Even today these figures are shocking to many – the war still hiding this terrifying menace in its shadow.