formerly a duchy of Germany. Until about 'Ito the county of Holstein formed part of the duchy of Saxony, and it was made a duchy in 1472. From 1460 to 1864 it was ruled by members of the house of Oldenburg, some of whom were also kings of Denmark. It is now the southern part of the Prussian province of Schleswig-Holstein. (See Schleswig-Holstein, and for history Schleswig-Holstein QUESTION.