The genealogy of the family began with the documentary 1226 John Ritter mentioned Ranzow, the lock on Rantzau settled in Plön. He served as a squire in the service of Adolf IV. and was to 1235 elevated to knighthood. Johann von Rantzau was the founder of the various lines Rantzauer, the following centuries, the history of Schleswig-Holstein influenced.
Heinrich (1526-1598) Heritage of Breitenburg, Melbeck and stubbornness Hagen, brought it to a sum of 20 Goods: of his cousins, he earned Rantzau and the Beautiful Weida, Furthermore Wandesburg, Hattstedt, Ovendorp, Stelnow, Rutschow, Tüschenbeck and Gronow, just to name a few, Finally, by marrying the heiress of Christine Hall, Rinteln and Drakenburg. For his favorite son Caius, he bought Rantzau. Caius died young, and the estate was already lost in the next generation.
Henry's eldest sons erheirateten the Norwegian cargo Brobin, Donnis (Donnet) and Senim and former named Franz was the progenitor of today thriving Danish Lehnsgrafen and barons Aasdahl, Brahesburg and Rosenwold. Christian, Henry's grandson bought it in 1649 the princely office Barmstedt against assignment of Rantzau.
The following year it formed in the immediate area county included the stains Barmstedt Rantzau and Elmshorn and 24 Villages. The line was founded by rich Count Christian Rantzau, the Emperor Ferdinand II. 1650 was elevated to the realm of count. Christian's son, Detlef (+1697) acquired to the county lions spar in Jutland, The local goods Demstrup, Display garden etc. His sons Christian Detlef (1697-1721) Wilhelm and Adolf, because of the desVerdachts committed fratricide 1722 was arrested and sentenced by a Danish court.