These leaflets were dropped in summer 1944 on Allied troops liberating Europe to undermine their morale.
 
The options to purchase are:
"Hell on earth" version
"Shadow over England" version
They can both come with, or without an autograph of the SS-Sturmbannführer Wernher von Braun (more as a joke - it's unlikely he really signed any of them)
 
V-1s started falling on London actually already on June 13, 1944 - a week after D-Day landing. Although formidable, due to the scale did not change the course of war, not English determination to win the war. At peak, more than one hundred V-1s a day were fired at southeast England, 9,521 in total, decreasing in number as sites were overrun until October 1944, when the last V-1 site in range of Britain was overrun by Allied forces,
 
The leaflet didn't lie - vastly superior V-2 was just about the corner with first hitting London on September 8. 
 
If you're interested in learning more, I recommend the Wikipedia article on the subject.