Fritz Kreis appears to have developed an automatic 2-speed derailleur system in the late 1930s, patenting it in 1940. He then went on to patent various refinements in the years up to 1950.

I believe that he was originally based in Chemnitz, home of many German bicycle companies. After the war Chemnitz was in the DDR (East Germany), and Fritz Kreis seems to have moved to Würzburg in Bavaria, in the Bundesrepublik (West Germany). Here he appears to have set up a company to manufacture his magnificent device. His system was exhibited at the 1950 and 1951 Frankfurt Cycle Shows.

There is a small army of merry inventors who have developed automatic gear systems for bicycles. Fritz Kreis stands out from this jolly rabble (and justifies his place on this web site) because his system was really manufactured and really sold to real cyclists who may even have really used it. Respect!