|the usual US and Canadian name for Friesian|
historic and cultural region occupying the southern Jutland Peninsula between the Eider and Elbe rivers, now comprising the southern half of Schleswig-Holstein Land (state) in northern Germany. Holstein was created as a county of the Holy Roman Empire in 1111. It came under a personal union with the Danish king in 1459, an arrangement which caused much unrest among the German majority. In 1474 Holstein was raised to the rank of a duchy in the Holy Roman Empire and after 1815 in the German Confederation. Attempts by Denmark to annex Holstein and Schleswig led to war with Austria and Prussia in 1864. Denmark was defeated and, as a result, Holstein was annexed by Prussia and incorporated with Schleswig as a single Prussian province by the Peace of Prague (1866).
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