V-2 rocket

The Vergeltungswaffe 2 (German for Vengeance Weapon 2), or V-2 Rocket was a ballistic missile developed by the Nazi German state on Earth in the first part of the 20th century. Originally known as the A-4, during testing this rocket was the first man made object to leave the Earth and enter space by reaching a altitude of 189 kilometers. The V-2 was made by slave labor - namely concentration camp prisoners, such as humans of the Jewish faith. The V-2 was used later in the Second World War by the Nazis against targets in Belgium and Great Britain.

Following the war, much of the technology wound up the hands of the United States of America and the Soviet Union. Wernher von Braun and Walter Dornberger were among the designers who were in American hands following the war. The V-2 Rockets were used as a foundation of the later 20th century space programs. (Historical accounts)

Alternate Timelines
While orbiting the planet Gateway, Doctor Leonard McCoy accidentally injected himself with an overdose of cordrazine. In a paranoid state, he left the USS Enterprise (NCC-1701). A landing party from the Enterprise followed him down, and they discovered the Guardian of Forever. McCoy, still suffering from the effects of the cordrazine overdose lept through the Guardian's portal, and altered history. McCoy saved the life of Edith Keeler - who had died in the original timeline. Due to Keeler's influence, the United States did not enter the Second World War until later. This gave Adolf Hitler the time he needed to develop nuclear weapons, and he was able to use them in conjunction with the V-2 Rocket to conquer Earth. (TOS episode The City on the Edge of Forever).

Learning that the Federation never existed in the altered timeline, Captain James T. Kirk and Mr. Spock followed McCoy back in time. They were able to prevent McCoy from saving Keeler's life, and prevented the altered timeline from ever taking place. (TOS episode The City on the Edge of Forever).