Like many other devices used in civilian life, current spacecraft have their origin in various military programs that are intended to cause the enemy as many casualties as possible. The V2 program deserves special attention to be a before and an after in the military field as well as in space.
V2 rockets (Vergeltungswaffe 2 or Retribution Weapon 2) were invented by the German army in World War II in order to terrorize the enemy (supersonic weapons are not heard approaching until they had already impacted). It was something as simple as a remote-controlled bomb (about 900 kg) and something as complex as a set of engines, gyroscopes, accelerometers and mixing liquid fuel (oxygen and alcohol).
This ballistic missile was built in underground factories using slave labor in very precarious conditions and despite the Allies bombed those factories, the truth is that towards the end of the war more than 4,000 artifacts had been released.
Although the V2 did not change the course of the war, it 
meant many advances in the space field. In fact, the director of this program, Wernher von Braun, was incorporated into NASA after the war to outrace the Soviet Union in the space program. Furthermore Von Braun was the main designer of the Saturn V rocket used in the Apollo and Skylab missions.
Even if fame is attributed to Von Brown, he never denied that he was inspired by the works of Pedro Paulet to build and design his rockets. After studying the movement of squid, Paulet concluded that an effective way of displacement in space would be the issuance of a liquid at high speed, producing a movement in the opposite direction to the flow of it (jet). The direct consequence of this is that wings, flaps, or gasoline/kerosene engines were not needed in the future artifacts.
Definitively, space history also has its dark chapters regardless of which over the years has brought enormous contributions both in civil and in science field.
Sources:
- Atlas ilustrado de la segunda Guerra Mundial; Ed: Susaeta
- BBC.com
Alfonso,
Tech For Space Editor