Duchy of Westphalia

The Duchy of Westphalia (German: Herzogtum Westfalen) was a historic territory in the Holy Roman Empire, which existed from 1180. It was located in the greater region of Westphalia, originally one of the three main regions in the German stem duchy of Saxony and today part of the state of North Rhine-Westphalia. The duchy was held by the Archbishops and Electors of Cologne until its secularization in 1803.

The duchy roughly comprised the territory of the present-day districts of Olpe and Hochsauerland, as well as the adjacent areas of the Soest district and Märkischer Kreis (Menden and Balve), from 1507 also the exclave of Volkmarsen (a former property of the Imperial Abbey of Corvey). The town of Soest was lost to the Duchy of Cleves-Mark after the Soest Feud in 1449.

The duchy bordered on the territory of the Prince-Bishops of Münster beyond the Lippe river in the north and on the Prince-Bishopric of Paderborn in the northeast; both ecclesiastical principalities also had emerged from the former Duchy of Saxony, while the Landgraviate of Hesse, the counties of Nassau and Waldeck in the southeast were part of the former stem duchy of Franconia. The Rhenish Duchy of Berg and the Westphalian County of Mark in the west remained an obstacle to a land connection with the Cologne territory on the Lower Rhine river.