The V-2

The V-2 ballistic missile (known to its designers as the A4) was the world’s first operational liquid fuel rocket. 6,084 V-2 missiles were built, 95% of them by 20,000 slave laborers in the last seven months of World War II at a unit price of $ 17,877. The V-2 – Not Ready for Production

When Wernher von Braun was recruited to assist Walter Dornberger in the development of liquid fuel rockets for the German Army in August 1932, only the tiniest baby steps toward development of rocket motors had been taken by the German Society for Spaceship Flight (VfR).

Source: www.astronautix.com