Mankind has been using simple black-powder propelled rockets for nearly a millennium but it wasn't until this date in 1926 that American inventor Robert Goddard launched the first liquid-fueled rocket.
In their adorable Teutonic way, the Germans saw the new technology and almost immediately went to work figuring out a way to use it to blow people up. Of course, it would need to be improved tremendously, because it would take a much larger, more complicated, and swoopier-looking rocket to carry a sufficiently lethal load of high explosives to a place with a large enough concentration of non-German people to make it worthwhile. Like London, for instance. On this date in 1942, they launched the first V-2 rocket. It thundered into the air above the launch pad and then blew up.
In dogged German fashion, however, they ironed the bugs out of the V-2 until it was dropping out of the skies over London with proper efficiency. So successful were they, that they managed to colonize the U.S. postwar space program and to populate bad '50s sci-fi, Antarctica, and even the far reaches of the internet with Space Nazis on the Moon.