Glashütte (I know, You don't have the letter "ü" on Your keyboard, and cannot spell it...) is a small town south of Dresden in the German State Sachsen (former Eastern Germany or German Democratic Republic). There used to be a silver mine in the old times, which depleted in the 17th century. To fight unemployment, the local ruler (Kurfürst) has encouraged watchmakers to settle there and start a watchmaking business. In the 19th century, a couple of "brands" have formed there (Not like watchbrands today, but close). One of them was A. Lange & Söhne (& sons), or Union and some others. When the russians occupied the area in 1945, they almost completely destroyed the town. After that, the "Volkseigene Betriebe Glashütte (VEB Glashütte) or Glashütter Uhren Betriebe (GUB)" have been formed by the communist regime out of the rests of the former watch industry. They produced rather simple mechanical watches, most of them for export.
After the reunification of Germany (1990), Mr. Pfeiffer bought the company for 1 German Mark and refounded the company under the name "Glashütte Original". Then they he sold the name A.Lange & Söhne to the Mannesmann Group, which at that time owned Jaeger LeCoultre and IWC. They relaunched the brand with Jaeger technic and employed an old man, Mr. Lange, a decendant of the former Watchmaker, but no watchmaker himself. Despite the name and the location, A. Lange & Söhne has nothing to do with the old history. Mr. Pfeiffer has also relaunched Union Glashütte as a "lower level brand" to Glashütte Original aproximately about 1995. Around 2000 he sold his company to the Swatch Group. Union Glashütte has been transfered to Certina, where they now build watches with ETA movements (Before they where inhouse manufacture movements).
To profit from the good name of Glashütte, also the Brands Mühle and others have set up some producitons there, although Mühle is only using Eta-Movements and the others just simple asian quartz movements.
Another Brand is Nomos, who started there also with Eta Movements, but has its own Movementproduction now.
One of the most important things of Glashütter mechanical watches is, that the movement is differently structured than in the swiss watches. The problem is, that I can hardly explain it in German and not at all in English.
I hope that little excursion in watch history has helpd.
BG
Thomas