Sauron forged the 1 ring to control the other 19 ones. He put a lot of his own power into it, which made him very vulnerable. 

  • The Dwarf rings failed and he had to recall them
  • The Elf rings were not under his influence, but did get to use his power anyways to establish Rivendell & Lothlorien
  • The Human rings got him the Nazgul, terrifying creatures that did nothing to help him in LotR
  • Creating the One Ring led to his destruction